scr jun 2015 pdf

JUNE 2015

BODYBUILDING EDITIONBy Chris Beardsley

WelcomeWelcome to the Bodybuilding Edition! In this edition,there are several studies of great interest for anyonewho follows bodybuilding research, or who is keen tounderstand the means by which anyone can increasemuscle mass and lose fat for improving their physique.In this column, Chris Beardsley discusses some of theissues around retention of lean body mass during dietsand what we might draw from the research literature.

The Bodybuilding Edition

IntroductionBodybuilding is a contest in which participants arejudged by their appearance. Successful participantspresent the judges with a physique that appears topossess the largest amount of muscle mass with thelowest levels of body fat in the proportions deemed tobe appropriately distributed across all body parts.Consequently, there is some value in developingposing routines that can draw attention towardsstrong points and attention away from weak points.Similarly, there is also value in designing specifictraining programs that can help develop any weakpoints. However, the essential purpose of successfulcompetition preparation is to build the maximumamount of muscle mass, and then to retain as much ofthis muscle mass as possible, while dieting down toreduce body fat to the lowest possible level.

Retention of muscle massRetaining as much muscle mass as possible duringdieting is a key task for any bodybuilding program. Asuccessful program will leave the competitor with asmuch of their hard-earned muscle mass as possible. Iftheir physique is mature, a successful program shouldideally allow a competitor to appear on the stage in acondition that it is quite close to their maximummuscular potential. Such programs typically involveboth resistance training (designed to help reducelosses in muscle mass) and aerobic training (designedto help increase losses in fat mass). However, theexact factors that determine how much of the weightlost is fat and how much is muscle are unclear.

Clarifying differences in body, muscle and fat massDebates regarding the amount of muscle mass thatcan be retained during periods of caloric restriction areoften derailed by a lack of a clear understandingregarding the outcome measures being discussed. Forexample, while an expert might note in passing that itis impossible to gain bodyweight during a period ofcaloric restriction because energy cannot be created ordestroyed (which is also known as the first law ofthermodynamics), a casual reader might interpret thisto mean that it is not possible according to the laws ofphysics to gain muscle mass during a diet, which isnot the case.

Simultaneous fat loss and muscle gainThe idea that it is never possible to gain muscle whilein a period of caloric restriction and losing fat is easilyrefuted by the research into resistance training orconcurrent resistance training and aerobic exercisestudies in obese or overweight populations. Suchstudies often report simultaneous losses of body andfat mass and gains in lean mass. For example, Williset al. (2012) reported that overweight or moderatelyobese adults performing both aerobic exercise andresistance training lost 2.4kg of fat mass while gaining0.8kg of lean mass, and both changes reachedstatistical significance. Similarly, Thomas et al. (2011)reported significant losses in fat mass of 3.4kg andincreases in lean mass of 0.8kg in overweight adultfemales after a resistance training and yoghurtsupplementation intervention. In a slightly different,but still overweight group, Avila et al. (2010) exploredthe effects of resistance training during a period ofcaloric restriction in overweight elderly adults andfound the subjects lost an average of 4.1kg of fatmass while increasing their lean mass by 0.8kg.Finally, McGuigan et al. (2009) reported significantreductions in body fat percentage of 2.6% andincreases in lean body mass percentage of 5.3% inoverweight and obese children following a program ofresistance training. These studies do not provide anymeaningful information about how body compositionmight change in bodybuilders during a similarlyextended period of caloric restriction, as there arevarious factors that differ substantially between thesepopulations, which will be described in the nextsection. However, they do demonstrate that it ispossible to gain muscle mass while losing body fat,while in a caloric deficit.

Why are bodybuilders different?Although there is evidence that resistance training orconcurrent resistance training and aerobic exercise inthe obese and overweight can lead to simultaneousreductions in fat mass and gains in lean mass, thereare several important factors that differ between thesepopulations and bodybuilders in preparation for acompetition. Such factors may mean that while it istheoretically possible to perform body recompositionin some populations, it is not feasible in bodybuilders.Firstly, obese and overweight subjects in trialsshowing simultaneous gains in muscle mass andlosses in fat mass are typically untrained, whichmeans that they can gain muscle mass very easily.Secondly, the subjects in these trials are oftenoverweight or obese, which may make it easier forthem to lose fat once engaged on an exerciseprogram. Thirdly, even when losing quantities of bodyfat, the subjects in these studies still finish theintervention with relatively poor body composition.This condition may not provide an incentive to reducelean mass at the expense of fat stores. Finally, otherfactors may also play a role, such as the rate ofbodyweight loss and the duration of the weight lossintervention, although it is unclear to what extentthese factors differ between the overweight and obesetrials and standard protocols used by bodybuilders.

Copyright Strength and Conditioning Research Limited, 2015

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3544497/

http://www.ncbi.nlm.nih.gov/pubmed/19130639



Retention of muscle mass in bodybuildersWhile it is possible for overweight and obese subjectsto lose fat mass and gain muscle mass using aresistance training or concurrent resistance trainingand aerobic exercise program, it is typical for casestudies or observational studies in bodybuilders toreport substantial losses of lean mass. Case studiesare a limited form of study design that report on theresults of a single individual. They can be valuable ifthe individual is representative of the norm but theycan be very misleading if the individual later turns outto be quite unusual, as might often be the case in anelite competitor.

Case studies of lean mass lost in natural bodybuildersThere have been a number of case studies performedassessing the loss of lean body mass during periods ofdieting in natural bodybuilders. Most recently,Robinson et al. (2015) reported on a young malenatural bodybuilder who lost 11.7kg of body weightover a 14-week period, of which the loss in fat masswas 6.7kg and the loss in lean mass was 5.0kg. Leanmass lost was 43% of the total body mass lost.Previously, Kistler et al. (2014) described how a youngmale natural bodybuilder lost 17.0kg of bodyweightover a 28 week period, of which the loss in fat masswas 10.4kg and the loss in lean mass was 6.6kg. Leanmass lost was 39% of the total body mass lost. Instark contrast to these results, a case study reportedby Rossow et al. (2013) detailed how a young malebodybuilding athlete lost 13.98kg of bodyweight overa 6-month period, of which the loss in fat mass was11.17kg and the loss in lean mass was 2.81kg. Leanmass lost was 20% of the total body mass lost. Theseresults indicate that when case studies are considered,the loss of lean mass as a proportion of total weightlost can range between 20 – 43%.

Observational studies of lean mass lost in natural bodybuildersAs might be expected, there have been far fewerobservational studies performed assessing the loss oflean body mass during periods of dieting in naturalbodybuilders. Van der Ploeg (2001) reported on theeffects of a 12-week preparation period in a group of 5female bodybuilders competing in the physiquedivision (although it was not completely clear thatthese athletes were natural). They found that of the5.8kg of body mass lost, the mean fat mass lost was4.42kg and the mean lean mass lost was 1.38kg,which represented 24% of total body mass. Similarly,Withers et al. (1997) reported that a group of 3 elitemale bodybuilders lost 6.91kg of body mass, of whichthe mean fat mass lost was 4.45kg and the mean leanmass lost was 2.46kg, which represented 36% of totalbody mass. These results demonstrate that inobservational trials (with admittedly small samplesizes), the loss of lean mass as a proportion of totalweight lost can range between 24 – 36%. It might besignificant that this range is smaller than in the casestudies, or it might be due to chance.

What can we conclude?From both types of study design (case studies andsmall sample-size observational trials), it appears thatin natural bodybuilding contest preparation, some lossof lean body mass should be anticipated and the sizeof this loss is likely to be around a quarter to a third oftotal bodyweight lost.






http://link.springer.com/article/10.1186/s12970-015-0083-x

Strength coach notes

Influence of resistance training frequency on muscular adaptations in well-trained men

The researchers concluded that resistance-trained males achieved greater gains in muscular size (and possibly also strength) when training muscle groups 3 days per week than when training muscle groups only 1 day per week.

Blood flow restricted exercise for athletes: a review of available evidence

The researchers concluded that low-load resistance training with BFR can bring about increases in muscular strength and size in well-trained athletes.

Influence of strength, sprintrunning, and combined strength and sprint running training on short sprint performance in young adults

The researchers concluded that combined full squat and sprint training is superior for improving short distance sprint running ability than either sprint-only training or full squat-only training, in resistance-trained amateurathletes.

Acute effects of elastic bands on kinetic characteristics during the deadlift at moderate and heavy load

The researchers concluded adding elastic resistance during the deadlift leads to reduced force production and increased power output at both moderate and high relative loads, and also potentially increased rate of force development at higher relative loads.

Kinematics and kinetics of multiple sets using lifting straps during deadlift training

The researchers concluded that using lifting straps does not alter the number of repetitions performed with 90% of 1RM over multiple sets but it does alter the way in which the deadlift is performed over these sets, by increasing the amount of time spent under tension by the prime mover muscles by increasing the duration of each repetition.

Quadriceps effort during squat exercise depends on hip extensor muscle strategy

The researchers concluded that back squats are most likely performed using a strategy that involves preferential gluteus maximus activity over hamstrings activity. This result suggests that the gluteus maximus and quadriceps are the key muscles to develop in order to improve performancein the back squat.

Effects of resistance exercise timing on sleep architecture and nocturnal blood pressure

The researchers concluded that the timing of when resistance training workouts are performed can affect the time taken to get to sleep, with resistance training performed closer to sleep leading to longer times taken to get to sleep. However, they also found that performing resistance training appears to lead to fewer times woken during sleep than a non-training control condition and that it does not affect nocturnal blood pressure.


Sports medicine notes

Acute effects of instrument assisted soft tissue mobilization vs. Foam rolling on knee and hip range of motion in soccer players

The researchers concluded that the instrument assisted soft tissue mobilization treatment was effective for increasing lower body flexibility acutely and that the effects of the treatment lasted for >24 hours.

Comparing the effects of self-myofascial release with static stretching on ankle range-of-motion in adolescent athletes

The researchers concluded that foam rolling, static stretching and a combined protocol of both foam rolling and static stretching all lead to acute increases in flexibility. They concluded that a combined protocol of both foam rolling and static stretching appears to have an additive effect in comparison with foam rolling alone. They concluded that all three protocols have time courses that lasted <10 minutes.

Incidence of running-relatedinjuries per 1000 h of running in different types ofrunners: a systematic review and meta-analysis

The researchers concluded that novice runners face a significantly greater risk of injury than recreational runners (17.8 vs. 7.7 injuries per 1,000 hours). This suggests that novice runners should engage caution when setting out on a running program.

Rationale, secondary outcome scores and 1-year follow-up of a randomised trial of platelet-rich plasma injections in acute hamstring muscle injury – the Dutch hamstring injection therapy study

The researchers concluded injections with platelet-rich plasma do not reduce the time taken to return to play. They also concluded that they do not affect 1-year re-injury rates. Additionally, they found that they have no effect on either hamstring flexibility or strength at the point of return to sport. They concluded that injections with platelet-rich plasma are not an effective treatment for hamstring strain injury.

Novel methods of instruction in ACL injury prevention programs, a systematic review

The reviewers concluded that the use of external cues may be beneficial foruse in ACL injury prevention programs on the basis that they improve performance and may also improve jump landing technique.

Acute hamstring injury in football players: associationbetween anatomical locationand extent of injury—a large single-center MRI report

The researchers concluded that the biceps femoris (long head) is the most commonly injured hamstring muscle. They concluded that although injuriesto the biceps femoris (long head) are split evenly between proximal and distal locations, the specific location most commonly injured is the proximalmyotendinous junction. For the medial hamstrings, the proximal regions were injured more often than the distal regions.

Tendon cross-sectional areais not associated with muscle volume

The researchers concluded that tendon cross-sectional area is not always associated with muscle volume. This may indicate that resistance training, or at least not all types of resistance training, increase tendon cross-sectional area in the same way as they increase muscle volume.


Strength and Conditioning Research

CONTENTS

BODYBUILDING EDITION....................................................................................................................................................2

CONTENTS.........................................................................................................................................................................5

1. STRENGTH & CONDITIONING, POWER AND HYPERTROPHY........................................................................................... 8

1. Influence of resistance training frequency on muscular adaptations in well-trained men, by Schoenfeld, Ratamess, Peterson, Contreras, Tiryaki-Sonmez, in Journal of Strength & Conditioning Research (2015)...................................................................................................... 9

2. Effects of resistance training under hypoxic conditions on muscle hypertrophy and strength, by Kurobe, Huang, Nishiwaki, Yamamoto, Kanehisa, and Ogita, in Clinical Physiology and Functional Imaging (2014)............................................................................................... 10

3. Blood flow restricted exercise for athletes: a review of available evidence, by Scott, Loenneke, Slattery, and Dascombe, in Journal of Science and Medicine in Sport (2015).......................................................................................................................................................... 11

4. Affective responses to acute resistance exercise performed at self-selected and imposed loads in trained women, by Focht, Garver, Cotter, Devor, Lucas, and Fairman, in Journal of Strength & Conditioning Research (2015) .......................................................................12

5. Assessment of neuromuscular function after different strength training protocols using tensiomyography, by Simola, Harms, Raeder, Kellmann, Meyer, Pfeiffer, Ferrauti, in Journal of Strength & Conditioning Research (2015) ...................................................................... 13

6. Carry-over of force production symmetry in athletes of differing strength levels, by Bailey, Sato, Burnett, Stone, Aspetar, LaGrange, in Journal of Strength & Conditioning Research (2015)...................................................................................................................................14

7. Influence of strength, sprint running, and combined strength and sprint running training on short sprint performance in young adults, by Marques, Gabbett, Marinho, Blazevich, Sousa, Van den Tillaar, Izquierdo, in International Journal of Sports Medicine (2015) ...........15

8. The effects of kettlebell training on strength, power, and endurance, by Girard and Hussain, in Physical Therapy Reviews (2015) .........16

9. The effects of high intensity interval-based kettlebells and battle rope training on grip strength and body composition in college-aged adults, by Quednow, Sedlak, Meier, Janot, and Braun, in International Journal of Exercise Science (2015) ...............................................17

10. Effects of general, specific and combined warm-up on explosive muscular performance, by Andrade, Henriquez-Olguin, Beltran, Ramirez, Labarca, Cornejo, and Ramirez-Campillo, in Biology of Sport (2015) ........................................................................................... 18

11. Stretch-induced reductions in throwing performance are attenuated by warm-up before exercise, by Mascarin, Vancini, Lira and Andrade, in Journal of Strength & Conditioning Research (2014)............................................................................................................... 19

12. The effects of static stretching on speed and agility: one or multiple repetition protocols? By Avloniti, Chatzinikolaou, Fatouros, Protopapa, Athanailidis, Avloniti, and Jamurtas, in European Journal of Sport Science (2015) ..................................................................20

2. BIOMECHANICS AND MOTOR CONTROL.......................................................................................................................21

13. Acute effects of elastic bands on kinetic characteristics during the deadlift at moderate and heavy load, by Galpin, Malyszek, Davis, Record, Brown, Coburn, and Manolovitz, in Journal of Strength & Conditioning Research (2015).............................................................22

14. Kinematics and kinetics of multiple sets using lifting straps during deadlift training, by Coswig, Freitas, Gentil, Fukuda, and Del Vecchio, in Journal of Strength & Conditioning Research (2015)...............................................................................................................................23

15. Quadriceps effort during squat exercise depends on hip extensor muscle strategy, by Bryanton, Carey, Kennedy, and Chiu, in Sports Biomechanics (2015).................................................................................................................................................................................... 24

16. The effects of varying load and repetition speed on energy expenditure during squats, by Barrett, Hastings, and Gottschall, in Journal ofFitness Research (2015)............................................................................................................................................................................... 25

17. The limiting joint during a failed squat – a biomechanics case series, by Flanagan, Kulik and Salem, in Journal of Strength & Conditioning Research (2015)...................................................................................................................................................................... 26

18. Effects of spine flexion and erector spinae maximal force on vertical squat jump height – a computational simulation study, by Blache and Monteil, in Sports Biomechanics (2015)............................................................................................................................................... 27

19. Hamstring fatigue and muscle activation changes during six sets of Nordic hamstring exercise in amateur soccer players, by Marshall, Lovell, Knox, Brennan, Siegler, and South, in Journal of Strength & conditioning Research (2015) ............................................................ 28

20. Neuromuscular strategies contributing to faster multidirectional agility performance, by Spiteri, Newton, Nimphius, in Journal of Electromyography and Kinesiology (2015).................................................................................................................................................. 29

21. Residual force enhancement in humans: current evidence and unresolved issues, by Seiberl, Power, and Hahn, in Journal of Electromyography and Kinesiology (2015).................................................................................................................................................. 30

22. Acute changes in kinematic and muscle activity patterns in habitually shod rear-foot strikers while running barefoot, by Strauts, Vanicek, and Halaki, in Journal of Sports Sciences (2015)........................................................................................................................... 31

23. Effect of initial position on the muscle activity of the hip extensors and amount of pelvic tilt during prone hip extension, by Yoon, Lee, and An, in Journal of Physical Therapy Science (2015)................................................................................................................................ 32



24. Influence of pelvic position and vibration frequency on muscle activation during whole body vibration in quiet standing by Kim and Seo,in Journal of Physical Therapy Science (2015)..............................................................................................................................................33

3. ANATOMY, PHYSIOLOGY, AND NUTRITION................................................................................................................... 34

25. Autophagic adaptation is associated with exercise-induced fibre-type shifting in skeletal muscle, by Tam, Pei, Yu, Sin, Leung, Au, and Siu, in Acta Physiologica (2015)................................................................................................................................................................... 35

26. Capillary growth, ultrastructure remodelling and exercise training in skeletal muscle of essential hypertensive patients, by Gliemann, Buess, Nyberg, Hoppeler, Odriozola, Thaning, and Mortensen, in Acta Physiologica (2015) ......................................................................36

27. Effects of resistance exercise timing on sleep architecture and nocturnal blood pressure, by Alley, Mazzochi, Smith, Morris, and Collier, in Journal of Strength & Conditioning Research (2015)...............................................................................................................................37

28. Cardiovascular adaptation and remodeling to rigorous athletic training, by Weiner, and Baggish, in Clinics in Sports Medicine (2015) . 38

29. Alterations of gut barrier and gut microbiota in food restriction, food deprivation and protein-energy wasting, by Genton, Cani, and Schrenzel, in Clinical Nutrition (2015).......................................................................................................................................................... 39

30. Effects of high-intensity intermittent exercise training on appetite regulation, by Sim, Wallman, Fairchild, and Guelfi, in Medicine & Science in Sports & Exercise (2015)..............................................................................................................................................................40

31. Effects of resistance training with and without caloric restriction on physical function and mobility in overweight and obese older adults, by Nicklas, Chmelo, Delbono, Carr, Lyles, and Marsh, in The American Journal of Clinical Nutrition (2015) ..................................41

32. Oxytocin reduces caloric intake in men, by Lawson, Marengi, DeSanti, Holmes, Schoenfeld, and Tolley, in Obesity (2015) ......................42

33. Creatine supplementation and lower limb strength performance: a systematic review and meta-analyses, by Lanhers, Pereira, Naughton, Trousselard, Lesage, and Dutheil, in Sports Medicine (2015).................................................................................................... 43

34. Tendon cross-sectional area is not associated with muscle volume, by Fukutani and Kurihara, in Journal of Applied Biomechanics (2015)......................................................................................................................................................................................................................44

35. Oxandrolone augmentation of resistance training in older women: a randomized trial, by Mavros, O'Neill, Connerty, Bean, Broe, Kiel, and Fiatarone, in Medicine & Science in Sports & Exercise (2015).............................................................................................................. 45

36. Effects of resistance exercise and the use of anabolic androgenic steroids on hemodynamic characteristics and muscle damage markersin bodybuilders, by Nadimi, Nasseri, and Nikookheslat, in The Journal of Sports Medicine and Physical Fitness (2015) ........................... 46

37. Dietary Intake of Competitive Bodybuilders, by Spendlove, Mitchell, Gifford, Hackett, Slater, Cobley, and O’Connor, in Sports Medicine (2015)........................................................................................................................................................................................................... 47

38. A nutrition and conditioning intervention for natural bodybuilding contest preparation – case study, by Robinson, Lambeth-Mansell, Gillibrand, Smith-Ryan, and Bannock, in Journal of the International Society of Sports Nutrition (2015) .................................................. 48

4. PHYSICAL THERAPY AND REHABILITATION................................................................................................................... 49

39. Acute effects of instrument assisted soft tissue mobilization vs. Foam rolling on knee and hip range of motion in soccer players, by Markovic, in Journal of Bodywork and Movement Therapies (2015).......................................................................................................... 50

40. Comparing the effects of self-myofascial release with static stretching on ankle range-of-motion in adolescent athletes, by Škarabot, Beardsley, and Štirn, in International Journal of Sports Physical Therapy (2015)........................................................................................51

41. Incidence of running-related Injuries per 1000 h of running in different types of runners: a systematic review and meta-analysis, by Videbæk, Bueno, Nielsen, and Rasmussen, in Sports Medicine (2015)........................................................................................................52

42. Novel methods of instruction in ACL injury prevention programs, a systematic review, by Benjaminse, Welling, Otten, and Gokeler, in Physical Therapy in Sport (2014)..................................................................................................................................................................53

43. Acute hamstring injury in football players: association between anatomical location and extent of injury—a large single-center MRI report, by Crema, Guermazi, Tol, Niu, Hamilton, and Roemer, in Journal of Science and Medicine in Sport (2015) ...................................54

44. Rationale, secondary outcome scores and 1-year follow-up of a randomised trial of platelet-rich plasma injections in acute hamstring muscle injury – the Dutch hamstring injection therapy study, by Reurink, Goudswaard, Moen, Weir, Verhaar, Bierma-Zeinstra, and Tol, in British Journal of Sports Medicine (2015)................................................................................................................................................ 55

45. The biomechanics of running in athletes with previous hamstring injury – a case-control study, by Daly, McCarthy Persson, Twycross-Lewis, Woledge, and Morrissey, in Scandinavian Journal of Medicine & Science in Sports (2015) ............................................................. 56

46. Evaluation of a treatment algorithm for patients with patellofemoral pain syndrome: a pilot study, by Selhorst, Rice, Degenhart, Jackowski, and Tatman, in International Journal of Sports Physical Therapy (2015).................................................................................. 57

47. Strengthening the hip muscles in individuals with patellofemoral pain: what can be learned from the literature?. By Dorey and Williams, in Physical Therapy Reviews (2015)............................................................................................................................................. 58

48. Prevalence and pattern of radiographic intervertebral disc degeneration in Vietnamese – a population-based study, by Ho-Pham, Lai, Mai, Doan, Pham, and Nguyen, in Calcified Tissue International (2015).................................................................................................... 59

49. Breathing techniques affect female but not male hip flexion range of motion, by Hamilton, Beck, Kaulbach, Kenny, Basset, DiSanto, and Behm, in Journal of Strength & Conditioning Research (2015)....................................................................................................................60



50. Viscoelastic stress relaxation in the hamstrings before and after a 10-week stretching program, by Peixoto, Andrade, Menzel, Araújo, Pertence, and Chagas, in Muscle & Nerve (2015)........................................................................................................................................61



1. STRENGTH & CONDITIONING, POWER AND HYPERTROPHY



Influence of resistance training frequency on muscularadaptations in well-trained men, by Schoenfeld,Ratamess, Peterson, Contreras, Tiryaki-Sonmez, inJournal of Strength & Conditioning Research (2015)

Background

IntroductionThe optimal structure of a resistance training programis unclear. Many variables can be altered, includingrelative load, volume, frequency, proximity tomuscular failure, rest period duration, muscle actionand repetition speed. Frequency is discussed in twocontexts. Firstly, in relation to the number of times perweek that a single body part can be trained effectively.Secondly, whether training should be performed astotal body, split, or individual body part routines.There are two underlying principles in each case:recovery and volume. For recovery, the question ishow long it takes (for either the individual or themuscle) to recover before training can be performedagain. Optimal frequency would be expected toproduce superior results. For volume, the question iswhether increasing frequency in order to increasevolume leads to superior results. Greater volumemight be expected to lead to increased gains.

Effect of frequency on strength gains (read more)Currently, the evidence indicates that training withdifferent volume-matched frequencies over the courseof a week has little effect on strength gains inuntrained individuals. This is on the basis of 6 long-term trials comparing >2 training groups, of which allbut one reported no differences between groups. Onthe other hand, the evidence indicates that trainingwith a higher volume-matched frequency mightpossibly be superior to training with a lower volume-matched frequency for increasing strength in trainedindividuals. However, this is on the basis of 3 long-term trials comparing >2 training groups, of which 1reported a benefit in favor of training with a higherfrequency for at least one of the outcome measuresfor strength while the other 2 trials reported nodifferences between groups.

Effect of frequency on size gains (read more)Currently, the evidence indicates that training withdifferent volume-matched frequencies over the courseof a week has little effect on gains in muscular size inuntrained individuals. This is on the basis of 4 long-term trials comparing >2 training groups, of which allbut one reported no differences between groups. Onthe other hand, the evidence indicates that trainingwith a higher volume-matched frequency mightpossibly be superior to training with a lower volume-matched frequency for increasing muscular size intrained individuals. However, this is on the basis of 3long-term trials comparing >2 training groups, ofwhich 1 reported a benefit in favor of training with ahigher frequency for at least one of the outcomemeasures of muscular size while the other 2 trialsreported no differences between groups.

OBJECTIVE: To compare the effects of trainingindividual muscle groups 1 day or 3 days per week onmuscular strength (as measured by 1RM bench pressand 1RM back squat) and size (as measured bymuscle thickness of the upper arms and thighs usingultrasound) in resistance-trained males.

POPULATION: 20 resistance-trained males, aged23.5 ± 2.9 years.

INTERVENTION: Subjects were allocated, pair-wiseinto 1 of 2 groups. The first group performed a splitroutine, in which multiple exercises were performedfor a muscle group in a single workout, with 2 – 3muscle groups trained per session. The second groupperformed a full body routine, in which 1 exercise wasperformed per muscle group per session and allmuscle groups were trained in each session. Bothgroups performed the same amount of total trainingvolume each week and both groups trained 3 days perweek.

What happened?

Muscular strengthThe researchers reported that the full body and splitgroups significantly increased in 1RM bench press by10.2kg (10.6%) and 6.3kg (6.8%), respectively andwhile there were no differences between groups, therewas a strong trend in favor of the full body group. Theresearchers reported that the full body and splitgroups significantly increased in 1RM back squat by13.8kg (11.3%) and 12.1 kg (10.6%), respectivelyand there were no differences between groups.

Muscular sizeThe researchers reported that the full body and splitgroups significantly increased in biceps brachii musclethickness by 3.2mm (6.5%) and 2.1mm (4.4%),respectively. The increase in the full body group wassignificantly greater than the increase in the splitgroup. The researchers reported that the full body andsplit groups significantly increased in triceps brachiimuscle thickness by 3.6mm (8.0%) and 2.3mm(5.0%), respectively. There was no significantdifference between groups but there was a strongtrend in favor of the full body group. The researchersreported that the full body and split groupssignificantly increased in vastus lateralis musclethickness by 3.6mm (6.7%) and 1.2 mm (2.1%),respectively. There was no significant differencebetween groups but there was a strong trend in favorof the full body group.

What did the researchers conclude?The researchers concluded that resistance-trainedmales achieved greater gains in muscular size (andpossibly also strength) when training muscle groups 3days per week than when training muscle groups only1 day per week.

LimitationsThe study was limited in that only two workoutprotocols were compared, both involving training just3 days per week.


http://www.strengthandconditioningresearch.com/hypertrophy/#5

http://www.strengthandconditioningresearch.com/strength/#5

http://www.strengthandconditioningresearch.com/strength/#5

http://pdfs.journals.lww.com/nsca-jscr/9000/00000/Influence_of_Resistance_Training_Frequency_on.96921.pdf

Effects of resistance training under hypoxic conditionson muscle hypertrophy and strength, by Kurobe,Huang, Nishiwaki, Yamamoto, Kanehisa, and Ogita, inClinical Physiology and Functional Imaging (2014)

BackgroundBlood flow restriction (BFR) training is used toincrease gains in muscular size. BFR training istypically prescribed as low-relative-load resistance-training (20 – 30% of 1RM) combined with blood flowrestriction applied in the form of either carefullycalibrated pressure cuffs or simple elastic wrappings.Previous studies have found that the use of BFRtraining can increase strength and muscle mass invarious populations, ranging from the elderly totrained athletes. Several theories have been putforward regarding mechanisms to explain thebeneficial effects observed following BFR training. It isthought that the mechanisms by which such increasesoccur might include increased fast-twitch fiberrecruitment, metabolic and hormonal alterations,intramuscular signaling, and cellular swelling.However, there is no current strong consensus arounda single, dominant mechanism by which BFR trainingexerts its effects. While there are currently noguidelines available for describing the use of BFRtraining in different populations, it is noted that it maybe possible to achieve gains in muscular size in manyindividuals with lower loads than are typicallyrecommended for resistance-training. The AmericanCollege of Sports Medicine (ACSM) recommends using>60% of 1RM as the desired relative load forincreasing muscular strength and size. However,research indicates that loads of 20 – 50% may beappropriate in combination with BFR. Thus, BFR incombination with resistance-training may be mostuseful for populations who cannot tolerate the largemechanica l loads that are assoc iated withconventional, heavy resistance-training, such as theelderly or infirm.

OBJECTIVE: To assess the effects of performingresistance training under hypoxic conditions onmuscular strength (as measured by 10RM elbowextension), muscular size (as measured by musclethickness using B-mode ultrasound), and hormonalresponses (as measured by blood sample analysis).

POPULATION: 13 healthy males, aged 23 ± 1 years,matched for physical fitness level and randomlyallocated into 1 of 2 groups: a hypoxic group and anormal oxygen group.

INTERVENTION: All subjects performed resistancetraining workouts comprising unilateral 10RM elbowextensions to muscular failure, 3 times per week for 8weeks, using a 1-minute inter-set rest period. Thehypoxic group breathed air with a 12.7% oxygencontent during each workout, which corresponds to analtitude of 4,000m. The normal oxygen groupbreathed normal air, which has an oxygen content of20.9%.

What happened?

Muscular strengthThe researchers found that 10RM elbow extensionincreased significantly in both groups in both trainedand untrained arms.

Muscular sizeThe researchers found that both groups significantlyincreased muscle thickness of the triceps brachii in thetrained arm. They also found that the increase in themuscle thickness of the triceps brachii in the trainedarm was significantly greater in the hypoxic groupthan in the normal oxygen group. There was nochange in the muscle thickness of the triceps brachiiof the untrained arm in either group.

Hormonal responsesThere were no differences between groups in respectof blood lactate responses to exercise. However, theresearchers noted that growth hormone levels afterexercise were significantly higher in the hypoxic groupthan in the normal oxygen group.

What did the researchers conclude?The researchers concluded that training under hypoxicconditions (equivalent to 4,000m altitude) wasbeneficial for increasing muscle hypertrophy.

LimitationsThe study was limited in that the mechanisms bywhich the superior increase in muscle size wasmediated were not explored.



Blood flow restricted exercise for athletes: a review ofavailable evidence, by Scott, Loenneke, Slattery, andDascombe, in Journal of Science and Medicine in Sport(2015)

BackgroundBlood flow restriction (BFR) training is used toincrease gains in muscular size. BFR training istypically prescribed as low-relative-load resistance-training (20 – 30% of 1RM) combined with blood flowrestriction applied in the form of either carefullycalibrated pressure cuffs or simple elastic wrappings.For a detailed introduction to BFR training, please seethe preceding study review.

OBJECTIVE: To perform a systematic review of theeffects of BFR training in well-trained athletes and tomake recommendations regarding best practices forthis training method in this population.

STUDY SELECTION: Studies were selected thatinvolved an athletic population, that explored theacute or long-term effects of BFR during eitherresistance or aerobic training, that were of any type ofstudy design, and that were published in a peer-reviewed journal.

What happened?

Study selectionThe researchers identified 12 papers describing 11acute and long-term investigations into BFR training inathletic populations. Of these 12 papers, 6 reported onthe long-term effects of low-load resistance trainingwith BFR, 2 reported on the acute effects of low-loadresistance training with BFR, 1 reported on the long-term effects of moderate-load resistance training withBFR, 1 reported on the long-term effects of aerobicexercise with BFR, and 1 reported on the case of anindividual who incurred rhabdomyolysis from low-loadresistance training with BFR.

Key findingsThe researchers found a number of studies reportedbeneficial muscular adaptations following low-load,long-term resistance training with BFR. After this typeof training, the athletes typically displayed increasedstrength and muscle size. In contrast, the researchersfound very little evidence to support the use ofmoderate or heavy loads in combination with BFR, orthe use of aerobic exercise in combination with BFRfor this purpose. The researchers noted that there islimited literature regarding the acute effects ofresistance training with BFR in athletes and whilethere are some indications that BFR might causegreater metabolic stress than traditional resistancetraining, there is also a clear indication that inter-individual acute responses to resistance training withBFR vary substantially, particularly between athletes ofendurance vs. strength and power backgrounds. Theynoted that this may be because strength and powerathletes are accustomed to performing in conditionswhere the availability of oxygen does not meet therequirements. This may imply that endurance athletesstand to gain more benefit from resistance trainingwith BFR than strength and power athletes but thishas not yet been explored directly.

What did the researchers conclude?The researchers concluded that low-load resistancetraining with BFR can bring about increases inmuscular strength and size in well-trained athletes.

LimitationsThe review was limited in that the researchers did notclearly assess the outcomes of resistance training withand without BFR.


http://www.sciencedirect.com/science/article/pii/S1440244015000961

Affective responses to acute resistance exerciseperformed at self-selected and imposed loads intrained women, by Focht, Garver, Cotter, Devor,Lucas, and Fairman, in Journal of Strength &Conditioning Research (2015)

BackgroundAffect is the term given in psychology to theexperience of emotions or mood states. Affect variesin at least three key ways, by valence (i.e. positive ornegative), by arousal levels (i.e. sympathetic nervoussystem activity), and also by motivational intensity(i.e. desire or impulse to act). Many researchers haveidentified that acute exercise leads to changes inaffect and that training variables within acute exercisecan modulate that effect. Specifically, it has beenfound that acute exercise reduces both anxiety anddepression and improves negative mood. Historically,there has been controversy regarding the dose-response of exercise on affect, with some studiesreporting a benefit of greater volumes of exercise andsome failing to report any greater benefit. Similarly,the effect of exercise intensity is also unclear, withsome studies reporting benefits of greater exerciseintensity and others failing to report any benefit. It isof great interest to researchers precisely how exercisecan be structured for maximum benefit to affect, asthis is believed to be beneficial for exercise adherenceand for helping individuals remain consistent with anexercise program. Affect is measured using a range ofself-reported scales. Most studies in athletes orrelating to athletic activities use the Profile of MoodStates (POMS) for mood-related affect investigations.For anxiety-specific investigations, the State-TraitAnxiety Inventory is also used. For fatigue-relatedaffect, the Physical Exhaustion scale of the Exercise-Induced Feeling Inventory (EFI) is commonly-used,while the Feeling Scale (FS) is used for specificassessment of affect in relation to exercise enjoyment.

OBJECTIVE: To compare the affective responses toacute resistance exercise at either self-selected or twodifferent imposed (40% of 1RM and 70% of 1RM)relative loads in recreationally trained women.Affective responses were measured using the FeelingScale pre, during, and post (at 0 and 15 minutes)each workout. This scale measures the range ofpleasure-to-displeasure on an 11-point scale rangingfrom very bad to very good. Intention to performfuture resistance training and self-efficacy were alsorecorded.

POPULATION: 20 resistance-trained females, aged23.2 ± 2.9 years.

INTERVENTION: All subjects performed 3 differentresistance training workouts. Each workout involved 3sets of 10 repetitions of the following 4 exercises: legextension, chest press, leg curl, and lat pull-down. Ineach workout, the relative load was different. In oneworkout, the relative load was 40% of 1RM; in thesecond workout, it was 70% of 1RM; in the thirdworkout, it was self-selected.

What happened?

AffectThe researchers found significant differences withineach type of workout for the changes in affect fromprior to during and from during to post (0 and 15minutes) but the final affect score for post-exercise at15 minutes was ultimately similar between groups.

Self-efficacy and intentionThe researchers found that the highest self-efficacywas reported using the self-selected relative load andthe lowest self-efficacy was reported using the 70% of1RM load. The intention to complete future resistancetraining was greatest in the order self-selected > 70%of 1RM > 40% of 1RM. There was no associationbetween self-efficacy or intention and affect.

What did the researchers conclude?The researchers concluded that training with a rangeof relative loads (self-selected or imposed) resulted insimilar improvements in affect in resistance trainedfemales. However, they also concluded that highestself-efficacy and intention to perform future resistancetraining occurred in resistance trained females whentraining with self-selected relative loads.

LimitationsThe study was limited in that it is unclear whetherthere was any relationship between self-reportedintention to perform future resistance training andactual performance of future resistance training.


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/Affective_Responses_to_Acute_Resistance_Exercise.96916.pdf

Assessment of neuromuscular function after differentstrength training protocols using tensiomyography, bySimola, Harms, Raeder, Kellmann, Meyer, Pfeiffer,Ferrauti, in Journal of Strength & ConditioningResearch (2015)

BackgroundTensiomyography (TMG) is a method for measuringcertain aspects of muscular contractile function thatmay also give insights into its muscle fiber types. TMGis carried out by placing a surface sensor on themuscle before applying an electrical stimulus while thelimb containing the muscle is restrained. The electricalstimulus therefore causes the muscle to contractagainst an isometric external resistance and no limbmovement occurs. Nevertheless, the muscle fibers stillshorten (and consequently it is assumed that thetendon is elongated in order that the muscle-tendonlength remains constant). The sensor measures thechange in the outward displacement of the muscleover time in the transverse plane in response to theelectrical stimulus. The rate of change of displacementis then provided as a proxy for true muscle fibercontraction velocity in the longitudinal plane of themuscle fiber itself. Since muscle fiber contractionvelocity is thought to be related to muscle fiber type,it is believed that TMG may provide insights into themuscle fiber type of different muscles in a far lessinvasive way than the current gold standard method oftaking muscle biopsies.

OBJECTIVE: To assess the sensitivity of TMGmeasurements to changes in muscle force andneuromuscular function of the rectus femoris bytaking measurements before and both immediatelyand at 24 and 48 hours after 5 resistance trainingprotocols based around a squat movement (multiplesets, drop sets, eccentric overload, flywheel, andplyometrics). The TMG measurements comprised:maximal radial displacement of the muscle belly (DM),contraction time between 10 and 90% Dm (TC), meanvelocity until 10% DM (V10), and mean velocity until90% DM (V90).

POPULATION: 14 male resistance-trained athletes,aged 23.0 ± 1.9 years.

INTERVENTION: All subjects performed 5 differentresistance training protocols. The multiple setsprotocol comprised: 4 sets of 6 repetitions with 85%of 1RM, an explosive concentric phase and a 2-secondeccentric phase, and 180 seconds rest between sets.The drop sets protocol comprised one set of 6repetitions plus 3 drop sets, starting with 85% of 1RMand dropping to 70%, 55% and 40% of 1RM in eachdrop set, using a 4-second eccentric phase and a 2-second concentric phase. The eccentric overloadprotocol comprised: 4 sets of 6 repetitions with 70%of 1RM in the concentric phase and 100% of 1RM inthe eccentric phase, an explosive concentric phaseand a 2-second eccentric phase, and 180 seconds restbetween sets. The flywheel protocol comprised: 4 setsof 6 repetitions with maximum effort, an explosiveconcentric phase and a 2-second eccentric phase, and180 seconds rest between sets. The plyometricsprotocol comprised 4 sets of 15 repetitions withmaximum effort, performed explosively and only inthe concentric phase, with 180 seconds of restbetween sets.

What happened? The researchers found that the training protocols allproduced a decrease in DM, TC, V10, and V90 frompre to immediately post-training. In addition, theyfound that DM, V10, and V90 remained significantlydecreased after 48 hours. Additionally, the researchersfound that the DM and V10 measures weresignificantly lower immediately post-training after thedrop set and flywheel protocols compared with theplyometric protocol. Since DM changes have beenlinked to muscle fatigue, this may indicate thatplyometrics are less fatiguing than the drop set andflywheel protocols.

What did the researchers conclude?TMG may be a useful method for comparing muscularresponses to exercise and may be able to predicttraining responses.

LimitationsThe study was limited as it is unclear yet whether TMGcan predict muscular adaptations to training.



Carry-over of force production symmetry in athletes ofdiffering strength levels, by Bailey, Sato, Burnett,Stone, Aspetar, LaGrange, in Journal of Strength &Conditioning Research (2015)

BackgroundMost people display a difference in force productionability between limbs (known as a lack of forceproduction symmetry). Indeed, reviews of theliterature have concluded that only differences >15%between legs are likely to reflect cases that areoutside the norm and which may therefore beindicative of increased injury risk (Hewitt et al. 2012).Traditionally, force production symmetry has beenassessed unilaterally using either dynamometry oreither isometric or dynamic exercises performed onforce plates. However, it is also feasible to measureunilateral vertical jump heights or unilateral horizontaland lateral jump distances using single-leg jump tests,which means that strength and conditioning coachescan perform simple tests without complex equipment.While force production symmetry has most frequentlybeen assessed during unilateral tests, it can also beassessed using bilateral tests, in which the forceoutput of each limb is measured separately. This maybe more reflective of the actual force productionsymmetry (of lack thereof) during bilateral exercises,such as the squat. A low level of force productionsymmetry during the squat has been associated withadversely altered joint angle movements during theexercise, which may either place athletes at greaterrisk of injury or lead to unfavorable adaptations andgreater strength imbalances. Even so, there areindications that long-term bilateral resistance trainingleads to improved force production symmetry ratherthan reduced force production symmetry, suggestingthat the problem may be largely self-correcting withconventional training.

OBJECTIVE: To assess whether bilateral forceproduction symmetry is associated during differentstandard tests recording ground reaction forces foreach leg (standing weight distribution, unloaded andlightly loaded jumps, and isometric strength). Bilateralforce production symmetry was calculated as thedifference between right and left ground reactionforces divided by the sum of right and left groundreaction forces, expressed as a percentage.

POPULATION: 63 athletes from NCAA Division Isports (31 males and 32 females), aged 18 – 23years.

INTERVENTION: All subjects performed standingweight distribution, unloaded and lightly loaded (20kg)squat and countermovement jumps, and isometricmid-thigh pulls while standing on a pair of force plates(one for each leg).

What happened? The researchers found that there were moderate-to-strong associations between the standing weightdistribution and jump measures of bilateral forceproduction symmetry. However, they did not find anysignificant associations between the standing weightdistribution and mid-thigh pull measures of bilateralforce production symmetry. Similarly, there were nosignificant associations between the jumping and mid-thigh pull measures of bilateral force productionsymmetry.

What did the researchers conclude?The researchers concluded that there are strongassociations between the standing weight distributionand jumping measures of bilateral force productionsymmetry, which suggests that symmetry is likely tobe similar in both of these tests. However, theyconcluded that mid-thigh pull measures of bilateralforce production symmetry differ from both standingweight distribution and jumping measures of bilateralforce production symmetry.

LimitationsThe study was limited in that it is unclear whetherbilateral force production symmetry is also similarbetween static weight distribution and jumping andother tasks.


http://journals.lww.com/nsca-scj/Abstract/2012/02000/Multidirectional_Leg_Asymmetry_Assessment_in_Sport.13.aspx

http://pdfs.journals.lww.com/nsca-jscr/9000/00000/CARRY_OVER_OF_FORCE_PRODUCTION_SYMMETRY_IN.96912.pdf

Influence of strength, sprint running, and combinedstrength and sprint running training on short sprintperformance in young adults, by Marques, Gabbett,Marinho, Blazevich, Sousa, Van den Tillaar, Izquierdo,in International Journal of Sports Medicine (2015)

BackgroundSprint running is a key athletic quality that iscontested in its own right in track and field, as well asbeing critical for success in many team sports, such assoccer, rugby, and both Australian Rules and AmericanFootball. Consequently, many researchers haveperformed extensive work into sprint running, bothoverall and in respect of certain specific aspects,including kinematics (joint angles) kinetics (forces andmoments), stiffness, electromyographic (EMG)activity, and the transfer of training to sprint running.As a result, there is a large body of knowledge inrespect of the features that are characteristic of elitesprinters and also of the training methods that maylead to best results. Sprint running performance isdetermined by the combination of stride length andstride frequency. Observational research indicates thatsome athletes rely on stride length for increasedspeed while others rely more on stride frequency forincreased speed. Analysis of biomechanics suggeststhat for improving stride length, hopping, boundingand stepping drills may be able to develop differentaspects of force production during the sprint runninggait cycle. Analysis of experimental trials suggeststhat sprint training, resistance training, plyometricsand resisted sprint training all produce significantimprovements in stride length. The effectiveness ofplyometrics may be related to observations that thestorage of elastic energy is important for sprintrunning performance. Indeed, researchers have foundthat this elastic energy storage becomes moreimportant with increasing sprinting speed. Thisindicates that drop jumps and other verticalplyometric exercises might be among the mosteffective training tools. Indeed, since biomechanicalanalysis suggests that the main role of the kneeextensors is one of shock absorption and increasedjoint stiffness upon ground contact, this furthersupports a role for reactive plyometric training thatstresses this muscle group, such as drop jumps.Related to this idea are the results of musculoskeletalmodeling research, which has reported that thelimiting factor for sprint running performance ismuscle contraction velocity. This suggests that trainingrate of force development for the key running musclesmay be the single most important factor in developingsprint running performance. This probably requires amix of training involving low loads with high velocities(which can be achieved using plyometrics) and highloads with low velocities. For improving stridefrequency, both experimental trials and biomechanicalanalysis indicate that combined heavy and explosivetraining along with overspeed running, using either adownhill slope or towing are all effective.

OBJECTIVE: To compare the effects of full squattraining vs. sprinting training vs. combined full squatand sprinting training on short distance (<30m) sprintrunning performance in amateur athletes.

POPULATION: 122 resistance-trained amateurathletes of different sports (soccer, futsal, track andfield, and team handball), aged 20.5 ± 2.5 years,randomly divided into 4 groups: full squat training (36subjects), combined full squat training and sprinting(32 subjects), sprinting training only (34 subjects) anda non-training control group (20 subjects).

INTERVENTION: All subjects in the training groupscompleted 2 training sessions per week for 6 weeks,while the control group performed only their normalactivity. The full-squat training group performed 2 fullsquat training sessions per week over 6 weeks; thesprinting group performed 2 sprinting sessions perweek over 6 weeks; the combined group performed 2combined sessions per week for 6 weeks but they onlyperformed half the volume of each training session, sothat total training volume was matched between the 3groups.

What happened? The researchers found 20m and 30m sprint runningtimes significantly decreased in all 3 training groups.However, they found that only the combined groupdisplayed a significant reduction in 10m sprint runningtime.

What did the researchers conclude?The researchers concluded that combined full squatand sprint training is superior for improving shortdistance sprint running ability than either sprint-onlytraining or full squat-only training, in resistance-trained amateur athletes.

LimitationsThe study was limited in that the researchers onlytested the squat exercise and it is unclear whetherperforming a different resistance training exercisewould have produced different results.


The effects of kettlebell training on strength, power,and endurance, by Girard and Hussain, in PhysicalTherapy Reviews (2015)

BackgroundUsing kettlebells for strength and conditioningpurposes in the US and Europe is a relatively recentoccurrence. This lack of mainstream usage means thatresearch has only been performed into their effects inthe last few years. Of pressing interest are the effectsof kettlebells on strength, power, and aerobic fitness.Additionally, because of their different bar path frommost conventional resistance training methods, anumber of researchers have been interested in theirbiomechanical characteristics, including muscleactivity, ground reaction forces, lumbar motion, andspinal loading. In these latter respects, the kettlebellswing has been most commonly researched. Althoughthe literature is still relatively scant, it seems thatkettlebells can be used for all types of populations todevelop physical fitness, including in rehabilitation forenhancing mobility and stability, in the conditioning ofendurance athletes for increasing maximal aerobiccapacity, and in development of strength athletes forincreasing explosive power. The literature to datesuggests that kettlebells could be a promising tool forstrength and conditioning coaches both as analternative to conventional techniques and also toachieve specific biomechanical goals. In particular,there are several reasons why kettlebells might beuseful for training for sprint running: kettlebell swingsappear to lead to greater medial hamstring activitythan lateral hamstrings activity compared to otherhamstrings exercises; kettlebell swings involve higherhorizontal-to-vertical ground reaction force ratios thaneither jump squats or conventional back squats; hip-dominant kettlebell swings could be a valuable high-velocity hamstrings exercise, particularly as there arefew conventional alternatives other than speeddeadlifts. Since sprint running involves greater medialhamstrings activity than lateral hamstrings activity,requires the production of horizontal forces, andinvolves high-speed hamstrings muscle actions, theseaspects of kettlebell training lend themselves to use intraining athletes who need to improve their sprintspeeds. Also of interest for physique athletes is thatkettlebell swings involve peak activation of the gluteusmaximus at a point near full hip extension. This pointis the same degree of hip flexion in which glutealactivity is highest during maximum voluntarycontractions. This suggests that the kettlebell swingmay be useful for developing the gluteus maximus,particularly as the main conventional exercisescurrently in use involve peak contractions of thegluteus maximus in hip flexion (squats and deadlifts).

OBJECTIVE: To perform a systematic review of theeffects of kettlebell training on strength, power, andendurance.

STUDY SELECTION: All randomized controlled trials,non-randomized trials, and pre-test/post-test studiesexploring changes in measures of strength, power,maximal aerobic capacity, or athletic performance inhuman adults as a result of long-term kettlebelltraining programs.

What happened?

Study selectionThe researchers identified 5 studies, including a totalof 141 healthy subjects, ranging from 18 to 72 yearsof age. The studies measured a wide range of fitnessoutcomes, including 1RM strength in variousexercises, maximum voluntary isometric contraction(MVIC) strength for a range of muscle groups, verticaljump height, aerobic endurance, and posturalperturbation.

Performance measuresThe researchers found that kettlebell training wasmoderately effective for increasing strength in a rangeof different measures. They noted that kettlebelltraining to improve athletic performance, proxies forpower output, and vertical jump height producedvaried results. They noted that only one studyreported on the effects of kettlebell training onmaximal aerobic power and this study found noeffects.

What did the researchers conclude?The researchers concluded that kettlebell training wasfound to improve certain measures of strength,proxies of power and athletic performance but notmaximal aerobic capacity.

LimitationsThe review was limited in that several new studieshave been published since the literature search wasperformed that would necessarily change the findingsof this review. In addition, the researchers did notadequately differentiate between genuine measures ofpower and proxy measurements of power (such as thevertical jump) and the literature is clear that the twoare not closely correlated.


http://www.maneyonline.com/doi/abs/10.1179/1743288X14Y.0000000163

The effects of high intensity interval-based kettlebellsand battle rope training on grip strength and bodycomposition in college-aged adults, by Quednow,Sedlak, Meier, Janot, and Braun, in InternationalJournal of Exercise Science (2015)

BackgroundUsing kettlebells for strength and conditioningpurposes in the US and Europe is a relatively recentoccurrence. This lack of mainstream usage means thatresearch has only been performed into their effects inthe last few years. For a detailed introduction to thenew research into kettlebell training, please see thepreceding study review.

OBJECTIVE: To assess the effects of a high intensityinterval training (HIT) program using kettlebells andbattle ropes on body composition (measured usingskin-fold calipers) and grip strength (measured usinga handgrip dynamometer).

POPULATION: 13 college-aged students accustomedto regular exercise (9 females and 4 males), aged20.9 ± 1.0 years.

INTERVENTION: All subjects in the training grouptrained 3 times per week for 5 weeks, where eachtraining session comprised a 20-minute HIT workoutwith a work-to-rest ratio of 1:1 (15 seconds exerciseand 15 seconds rest). In each HIT workout, thesubjects alternated 2 minutes of a kettlebell exercise(kettlebell swing, kettlebell swing and goblet squat,kettlebell shovel, kettlebell 1-arm alternating swing,kettlebell burpee) with 2 minutes of battle ropeexercises (alternating waves, jumping jacks, parallelwaves, rotational slam, jump slam) for 4 sets of eachof the 5 exercises.

What happened?

Body compositionThe researchers found that the training groupdisplayed a non-significant reduction in body fatpercentage (from 22.46 ± 7.81% to 22.00 ± 7.45%)while the control group did not change at all (from20.67 ± 5.43% to 20.83 ± 6.39%).

Hand grip strengthThe researchers found that the training groupdisplayed a significant increase in right handgripstrength from 39.5 ± 10.6kg to 42.1 ± 11.5k g andthere was a non-significant increase in left handgripstrength from 36.9 ± 12.1kg to 38.2 ± 11.6kg. Therewere no significant changes in the control group.

What did the researchers conclude?The researchers concluded that an HIT programinvolving kettlebells and battle ropes significantlyincreases right handgrip strength but does not alterbody composition.

LimitationsThe study was limited in that it only measuredhandgrip strength and body composition. Since theprogram involved an HIT protocol, it would have beeninteresting to see whether it affected maximal aerobiccapacity.


http://digitalcommons.wku.edu/ijes/vol8/iss2/3/

Effects of general, specific and combined warm-up onexplosive muscular performance, by Andrade,Henriquez-Olguin, Beltran, Ramirez, Labarca, Cornejo,and Ramirez-Campillo, in Biology of Sport (2015)

BackgroundIt is generally accepted that warm-ups improvesubsequent athletic performances. There are severalmechanisms by which warm-ups might be effective.Most of these mechanisms are physiological, and mostphysiological mechanisms are thought to arise fromtemperature-related factors. Firstly, it is thought thatwarm-ups lead to decreased viscous resistance of themuscles: increasing muscle temperature may reducethe passive resistance or stiffness of muscle tissue,making the fibers more elastic, which is likely toimprove both absolute force and rate of forcedevelopment. Secondly, it is thought that warm-upslead to increased oxygen delivery to the muscles:increasing muscle temperature may improve oxygendelivery to the muscles as a result of a rightward shiftin the oxy-haemoglobin dissociation curve (this shiftmakes it easier for hemoglobin to release the oxygenthat is bound to it and therefore increases delivery ofoxygen to the muscles) as well as by greatervasodilation. This is likely to improve mainly longerduration anaerobic and aerobic performances. Thirdly,warm-ups are thought to allow increased anaerobicmetabolism: increased muscle temperature appears tocause an elevation in muscle glycogen breakdown,which may then improve subsequent short-termanaerobic performance. Fourthly, warm-ups arethought to lead to increased nerve conduction rate:increased muscle temperature increases thetransmission speed of nervous impulses, which islikely to increase both reaction times and rate of forcedevelopment. Fifthly, warm-ups are believed to lead tometabolic effects that might improve oxygen delivery:the metabolic byproducts of exercise might lead toincreased oxygen delivery to the muscles as a resultof a rightward shift in the oxy-haemoglobindissociation curve and increased vasodilation, just asincreased muscle temperature does. Sixthly, warm-ups may lead to elevation of baseline oxygenconsumption: where tasks can be started with anelevated level of oxygen consumption, the initial partof the task will not be performed anaerobically,thereby placing a reduced strain on the athlete at thebeginning of the workout or competition. Seventhly,warm-ups have been proposed to lead to changes incontractile apparatus: during periods of inactivity, thenumber of bonds between actin and myosin filamentsbonds increases and this elevates the stiffness of amuscle. Physical activity breaks these bonds, reducingmuscle stiffness. An active warm-up involving largemuscular excursions to lengthen muscles may breakactin-myosin bonds and reduce the passive stiffness ofmuscle, thereby increasing subsequent rate of forcedevelopment. Finally, it is well-known that prioractivity can cause a post-activation potentiation (PAP)effect in subsequent activities.

OBJECTIVE: To compare the effects of general,specific and combined (general and specific) warm-upson squat jump height, countermovement jump height,drop jump (from 60cm) reactive strength, byrecording performance in each jump before and afterthe warm-up.

POPULATION: 10 untrained males, aged 20.6 ± 0.64years.

INTERVENTION: All subjects performed jumpingtests after 6 different warm-up protocols, comprising15 minutes of passive rest, 5 minutes of running at70% of maximum heart rate, 5 minutes of staticstretching, 5 minutes of jumping (3 sets of 8countermovement jumps and 3 sets of 8 drop jumpsfrom 60cm), and combined (running, stretching, andjumping warm-ups combined).

What happened?

Squat jump heightThe researchers found that only the running andjumping warm-ups led to a significant improvement insquat jump height. In contrast, passive rest led to asignificant reduction in squat jump height.

Countermovement jump heightThe researchers found that the running, jumping,stretching, and combined warm-ups caused asignificant improvement in countermovement jumpheight. In contrast, passive rest did not cause anysignificant increase in countermovement jump height.

Drop jump reactive strengthThe researchers found that only the jumping warm-upled to a significant improvement in drop jump reactivestrength.

What did the researchers conclude?The researchers concluded that different warm-upslead to improvements in different types of jump. Theynoted that only the specific warm-up (jumping) wasable to improve drop jump reactive strength.

LimitationsThe study was limited in that it is unclear how long thebenefits of the warm-up would last before wearing off.


http://biolsport.com/fulltxt.php?ICID=1140426

Stretch-induced reductions in throwing performanceare attenuated by warm-up before exercise, byMascarin, Vancini, Lira and Andrade, in Journal ofStrength & Conditioning Research (2014)

BackgroundIt is generally accepted that warm-ups improvesubsequent athletic performances. There are severalmechanisms by which warm-ups might be effective.Most of these mechanisms are physiological, and mostphysiological mechanisms are thought to arise fromtemperature-related factors. For an introduction to themechanisms of warm-ups, please see the precedingstudy review.

OBJECTIVE: To compare the effects of staticstretching, a dynamic warm-up, or a combination(both static stretching and a dynamic warm-up), on 2-hand medicine ball distance thrown (as measured bytape measure) and 1-hand handball throwing velocity(as measured by radar gun), in young female handballplayers.

POPULATION: 21 female handball players, aged 16.2± 1.0 years.

INTERVENTION: All subjects performed the throwingtests after each of 3 different warm-ups. The staticstretching warm-up comprised 5 different stretches,as follows: arm abduction at 90 degrees withhorizontal flexion, shoulder abduction with the upperlimb behind the head, upper limb abduction to 135degrees with horizontal extension, upper limbabduction at 90 degrees with horizontal extension,and shoulder internal rotation with the hand behindthe body. The dynamic warm-up comprised just 2exercises: shoulder external rotation and lunge withmulti-planar shoulder blade squeeze. The combinedwarm-up comprised both the static stretching anddynamic warm-up exercises.

What happened?

Medicine ball distance thrownThe researchers found that the medicine ball distancethrown was significantly greater in the dynamic warm-up (2.86 ± 0.28m) than in the static stretching (2.76± 0.30m) condition and non-significantly greater inthe dynamic warm-up (2.86 ± 0.28m) than in thecombined (2.77 ± 0.29m) condition.

Handball throwing velocityThe researchers found that handball throwing velocitywas non-significantly greater in the dynamic warm-upcondition (15.1 ± 1.8m/s) than in both the staticstretching (14.8 ± 1.6m/s) and combined (14.9 ±1.8m/s) conditions.

What did the researchers conclude?The researchers concluded that performing a staticstretching warm-up prior to a throwing event leads toreduced performance in comparison with a dynamicwarm-up. It is possible that combining the staticstretching warm-up with a dynamic warm-up mayreduce some of the adverse effects of static stretchingon performance.

LimitationsThe study was limited by the presence of several non-significant trends that were difficult to interpret.



The effects of static stretching on speed and agility:one or multiple repetition protocols? By Avloniti,Chatzinikolaou, Fatouros, Protopapa, Athanailidis,Avloniti, and Jamurtas, in European Journal of SportScience (2015)

BackgroundFlexibility is important for both athletes and for thegeneral population. Flexibility is defined as the abilityto move through a specific joint range of motion(ROM). Stretching is commonly used to helpindividuals achieve greater joint ROM. Researchershave generally proposed two types of mechanism bywhich increases in flexibility can be achieved. Onetype of mechanism involves a mechanical change inthe behavior of the muscle tissue while the other typeinvolves a change in sensation. However, there are atleast four theories that detail ways in which some kindof mechanical change could occur: viscoelasticdeformation, plastic deformation, increased number ofsarcomeres in series, and neuromuscular relaxation.However, the evidence to support these has beenfound to be weak. In contrast, many studies havereported that the only variable that changes followingstretching programs in tandem with flexibility is thesensation of pain (i.e. maximum pain and onset ofpain) during the stretch. This supports the sensationtheory of stretching. Researchers advocating thistheory have formulated the hypothesis that stretchingincreases flexibility by reducing the sensation ofincreasing muscle length. Nevertheless, irrespective ofhow stretching changes joint flexibility, it is apparentthat it can achieve increases in joint ROM that last > 1day. There are two main types of stretching that areexplored in the literature: static and dynamicstretching. Static stretching involves moving a joint tothe end of its ROM and holding this stretched positionfor a set period of time. On the other hand, dynamicstretching involves controlled movements through theactive ROM for a joint. While both static and dynamicstretching have been found to improve joint ROM,static stretching performed for >45 seconds appearsto lead to meaningful acute reductions in performancetasks, such as vertical jumping, whereas dynamicstretching performed for long durations appears tolead to either no improvement or small improvementsin the same type of actions. It is interesting to notethat reviews of the chronic effects of static stretchinghave actually found beneficial effects on both athleticperformance and strength measures. The literature iscurrently conflicting regarding whether regular staticor dynamic stretching is effective for reducing the riskof sports injury, whether the stretching is performedimmediately prior to exercise or at another time.Additionally, the exact duration of stretches, the totalvolume and frequency of stretching per week, and therest periods between stretches that are optimal for themost efficient increases in joint ROM are currentlyunknown.

OBJECTIVE: To compare the effects of single andmultiple repetitions of a moderate duration stretch(<60 seconds) on speed (10m and 20m sprint runningability) and agility (T-test) performance.

POPULATION: 40 trained athletic males, randomlyallocated to either a single repetition group (aged 21.2± 1.6 years) or a multiple repetition group (aged 20.8± 0.8 years).

INTERVENTION: All subjects performed 5 trials: acontrol trial (no stretches) and 4 static stretching trialsof 5 lower body stretches of 20 seconds, 30 seconds,40 seconds, or 60 seconds total duration. The singlerepetition group performed each duration of stretch inits entirety. The multiple repetition group performedeach stretch divided into 10-second segments (2 setsof 10 seconds, 3 sets of 10 seconds, 4 sets of 10seconds, and 6 sets of 10 seconds). Stretches wereperformed 3 minutes prior to the performance tests.

What happened?

Sprint runningThe researchers found that sprint running ability over10m and 20m appeared to be unchanged by either thesingle or multiple repetition approach. However, 10msprint running performance appeared to be improvedby both protocols equally after the 20-second stretchduration only.

AgilityThe researchers found that agility performance in theT-test appeared to be unchanged by either the singleor multiple repetition approach.

What did the researchers conclude?The researchers concluded that the acute effects ofstatic stretching on short distance sprint running andagility performance are unaffected by performing thestretches as either one single repetition or as multipleindividual repetitions.

LimitationsThe study was limited in that previous studies havereported very varied effects of static stretching onsprint running performance. It is therefore unclearhow static stretching affects either agility or sprintrunning ability.


http://www.tandfonline.com/doi/abs/10.1080/17461391.2015.1028467


2. BIOMECHANICS AND MOTOR CONTROL



Acute effects of elastic bands on kinetic characteristicsduring the deadlift at moderate and heavy load, byGalpin, Malyszek, Davis, Record, Brown, Coburn, andManolovitz, in Journal of Strength & ConditioningResearch (2015)

BackgroundThe deadlift is an exercise performed by lifting abarbell resting on the ground. It is a common exercisefor developing lower body strength and size for bothathletes and bodybuilders, as well as being contestedas part of the three lifts in powerlifting. It differs frommost other barbell exercises in that the first part ofthe lift involves mostly concentric muscle actions andthe second part of the lift involves mostly eccentricmuscle actions. Thus, there is no stretch-shorteningcycle in operation for at least the first repetition of aset of deadlifts. Much less research has beenperformed into the deadlift in comparison with theback squat. However, some studies have comparedthe biomechanics of the deadlift with the back squatand noted large differences. Most notably, the deadliftappears to involve a sequential order of joint anglemovements, with consecutive knee extension and thenhip extension, while the back squat involvessimultaneous knee and hip extension. This means thatthe deadlift likely involves meaningful length changesin the hamstrings muscle, while the back squat doesnot, which probably contributes to its ability todevelop this muscle group. Unlike the back squat,there have been few biomechanics studiesinvestigating the exercise technique variables in thedeadlift that make a difference to the effect of theexercise on the working musculature. Consequently,the effects of load and depth are largely unknown.However, a small number of investigators haveexplored the differences between sumo andconventional deadlifts. In general, such studies havefound more similarities than differences. However, thesumo deadlift appears to involve greater stimulus forthe quadriceps and tibialis anterior while theconventional deadlift appears to involve greater calfmuscle stimulus. Additionally, the conventional deadliftmay involve a greater amount of work done (becauseof the larger difference travelled) while the sumodeadlift may involve lower lumbar spinal loadsbecause the torso is less horizontally-inclined. Inaddition, researchers have found that the exactposition of the sticking region in the deadlift does notdiffer largely between the sumo and conventionaldeadlifts but does differ greatly between individuals.Programing for working through the sticking region inthe deadlift may thus require precise consideration ofan athlete’s individual weaknesses in order to moveforwards.

OBJECTIVE: To compare the force (peak, relative andaverage), rate of force development (peak), velocity(peak, average), and power (peak, relative, average),during the deadlift with either a combination of freeweights and elastic resistance or free weights only,using both moderate (60% of 1RM) and heavy (85%of 1RM) relative loads.

POPULATION: 12 resistance-trained males, aged24.1 ± 2.4 years, with a 1RM deadlift of 188.6 ±16.1kg.

INTERVENTION: All subjects performed deadlifts in 6different conditions, divided into 3 resistance types (2variable and one conventional) and 2 relative loads:60% of 1RM and 85% of 1RM. The 2 variableresistances comprised using bands to representdifferent proportions of the overall resistance, whenmeasured at the top of the movement: either 15%bands (and 85% barbell) or 35% bands (and 65%barbell). This meant that at the bottom of themovement, the conditions using bands involved lessabsolute load.

What happened?

ForceThe researchers found that for both relative loads(60% of 1RM and 85% of 1RM) force was significantlygreater in the order conventional > variable (15%bands) > variable (35% bands), when measuredeither as peak, average or relative force. This impliesthat as the proportion of the load comprised of bandsincreases, force decreases, irrespective of the loadused.

Rate of force developmentThe researchers found no significant difference in rateof force development between any of the three(variable or conventional) conditions at 60% of 1RM.However, at 85% of 1RM, rate of force developmentduring the second elastic resistance condition (35%bands) was greater than during either of the other twoconditions.

PowerThe researchers observed that both variable conditionsled to significantly greater power (peak, average andrelative) than the conventional condition at both 60%of 1RM and 85% of 1RM.

What did the researchers conclude?The researchers concluded adding elastic resistanceduring the deadlift leads to reduced force productionand increased power output at both moderate andhigh relative loads, and also potentially increased rateof force development at higher relative loads.

LimitationsThe study was limited as it was an acute investigationand it is unclear whether different results would beachieved by training over the long-term using either adeadlift with variable resistance or with conventionalloading.


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/Acute_Effects_of_Elastic_Bands_on_Kinetic.96917.pdf

Kinematics and kinetics of multiple sets using liftingstraps during deadlift training, by Coswig, Freitas,Gentil, Fukuda, and Del Vecchio, in Journal ofStrength & Conditioning Research (2015)

BackgroundThe deadlift is an exercise performed by lifting abarbell resting on the ground. It is a common exercisefor developing lower body strength and size for bothathletes and bodybuilders, as well as being contestedas part of the three lifts in powerlifting. For anintroduction to the deadlift exercise, please see thepreceding study review.

OBJECTIVE: To compare average and peak power,average and peak force, displacement, duration, andvelocity (measured using a linear potentiometer) inthe concentric and eccentric phases of 3 sets ofdeadlift to muscular failure, both with and withoutlifting straps.

POPULATION: 11 resistance-trained males, aged 25± 3.3 years, with an average of 4.0 ± 2.6 years ofresistance training experience and a 1RM deadlift of180.0 ± 14.8kg.

INTERVENTION: All subjects performed 3 sets of thedeadlift to failure at 90% of 1RM, both with andwithout lifting straps, on separate days.

What happened?

Number of repetitionsThe researchers found that the number of repetitionsperformed did not differ significantly between the 2conditions across each of the 3 sets, with the meanbeing 12 repetitions in total for both conditions (withstraps, sets 1 – 3: 5 ± 2, 4 ± 2, and 3 ± 2repetitions; without straps, sets 1 – 3: 5 ± 1, 4 ± 1, 3± 1 repetitions).

Bar speed and durationThe researchers found that the bar speed decreased inthe condition without straps from sets 1 – 3 but thisreduction did not occur in the condition with straps.The bar speed was therefore significantly greater inthe condition without straps compared to the conditionwith straps in sets 1 and 2 but not in set 3.Conversely, the average duration of each repetitionwas significantly greater in the with straps conditionthan in the without straps condition during all sets.

Force and powerThe researchers found that mean and peak force wereboth higher in the condition with straps compared tothe condition without straps. There was no differencebetween conditions for power.

What did the researchers conclude?The researchers concluded that using lifting strapsdoes not alter the number of repetitions performedwith 90% of 1RM over multiple sets but it does alterthe way in which the deadlift is performed over thesesets, by increasing the amount of time spent undertension by the prime mover muscles by increasing theduration of each repetition.

LimitationsThe study was limited as it was an acute investigationand it is unclear whether different results would beachieved by training over the long-term using liftingstraps or not using lifting straps.


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/KINEMATICS_AND_KINETICS_OF_MULTIPLE_SETS_USING.96914.pdf

Quadriceps effort during squat exercise depends onhip extensor muscle strategy, by Bryanton, Carey,Kennedy, and Chiu, in Sports Biomechanics (2015)

BackgroundThe back squat is an exercise performed with a barbellresting on the upper trapezius. It is the standardexercise for developing lower body strength and sizefor both athletes and bodybuilders. A great deal ofresearch has been performed into the back squat.Long-term trials have established that it is effectivefor improving lower body strength and power as wellas vertical jumping and sprint running performance.Biomechanics studies have found that there areseveral key exercise technique variables that make adifference to the effect of the exercise on the workingmusculature. In particular, it has been found that theload has a more pronounced effect than squat depthon the force required from the ankle plantar-flexors,that depth is a more significant factor than load forthe force required of the knee extensors, and thatboth depth and load are key for determining the forcerequired from the hip extensors. Thus, both squatdepth and load should be considered as variables inusing squats depending on which muscle groups are tobe strengthened and to what extent. In terms of othertechnique variables, researchers have found thatstance width and foot position make little difference tomost of the lower body muscles except the gluteusmaximus. Therefore, despite the claims of somepopular strength coaches and bodybuilders, usingdifferent stance widths during squats are unlikely todevelop different parts of the quadriceps and stressingindividual quadriceps muscles or different parts of thequadriceps will likely require more careful exerciseselection. However, using a wider stance does appearto increase gluteus maximus activity during squats.

OBJECTIVE: To build musculoskeletal models basedupon net joint moments calculated by inversedynamics to understand the relative importance of thegluteus maximus and hamstrings muscles as hipextensors during the back squat. This was achieved bycomparing a model in which the hamstrings andgluteus maximus operated equally with a model inwhich the gluteus maximus operated preferentially.

POPULATION: 10 trained females (with >1 year backsquat training experience and able to perform a 1RMback squat with a load >1 times bodyweight), aged22.5 ± 2.1 years.

INTERVENTION: Two musculoskeletal models wereconstructed based upon the net joint moments derivedfrom data captured from the subjects as theyperformed back squats with 50%, 60%, 70%, 80%,and 90% of 1RM. Data were captured using motionanalysis software to record joint angle movements andforce plates to record ground reaction forces duringperformance of the back squat. The first modelinvolved equivalent gluteus maximus and hamstringsactivation (Model 1) and the second model involvedpreferential gluteus maximus activation (Model 2).

What happened? The researchers found that the relative muscular effortof the knee extensors exceeded the maximumpossible torque in the first model, making equalhamstrings and gluteus maximus involvement highlyunlikely as a strategy. Relative muscular effort of amuscle group during the back squat is the ratio of themoment required in the back squat relative to themoment that can be produced during a maximalvoluntary isometric contraction (MVIC). The maximumrelative muscular effort of the knee extensors in thefirst model was 120 ± 36%, which is >100% of MVIC,while the relative muscular effort only reached 87 ±28% in the second model, which used preferentialgluteus maximus activation.

What did the researchers conclude?The researchers concluded that back squats are mostlikely performed using a strategy that involvespreferential gluteus maximus activity over hamstringsactivity. This result suggests that the gluteus maximusand quadriceps are the key muscles to develop inorder to improve performance in the back squat.

LimitationsThe study was limited in that it was based upon thecomparison of musculoskeletal models and thereforewas reliant upon the accuracy and completeness ofthe assumptions that were used to construct themodels.



The effects of varying load and repetition speed onenergy expenditure during squats, by Barrett,Hastings, and Gottschall, in Journal of FitnessResearch (2015)

BackgroundThe back squat is an exercise performed with a barbellresting on the upper trapezius. It is the standardexercise for developing lower body strength and sizefor both athletes and bodybuilders. A great deal ofresearch has been performed into the back squat. Foran introduction to the squat exercise, please see thepreceding study review.

OBJECTIVE: To compare the effects of different loadsand speeds of squats on heart rate and estimatedenergy expenditure (from heart rates) over work-matched 4-minute exercise periods.

POPULATION: 15 subjects (6 males and 9 females),between 18 and 40 years of age.

INTERVENTION: All subjects completed 4 conditionscomprising the same amount of work (force xdistance) for 4 minutes with either 20kg, 15kg, 10kg,or 5kg. The different loads were matched withdifferent repetition durations (of equal concentric andeccentric phases): the 20kg required 8 seconds, the15kg required 6 seconds, the 10kg required 4 secondsand the 5kg required 2 seconds. This resulted in the20kg weight being lifted 30 times, the 15kg weightbeing lifted 40 times, the 10kg weight being lifted 60times and the 5kg weight being lifted 120 times. Inthis way, the total work done was matched betweenconditions.

What happened?

Heart ratesMean heart rate increased steadily with decreasingload and increasing repetitions (20kg: 118 ± 18,15kg: 120 ± 22, 10kg: 127 ± 25, and 5kg: 135 ±23bpm). Similarly, peak heart rate increased steadilywith decreasing load and increasing repetitions (20kg:128 ± 25, 15kg: 132 ± 26, 10kg: 137 ± 27, and 5kg:147 ± 26bpm).

Estimated energy expenditureAs expected, since the calculation is based on heartrate, estimated energy expenditure also increasedsteadily with decreasing load and increasing numberof repetitions: (20kg: 35 ± 12, 15kg: 38 ± 13, 10kg:42 ± 17, and 5kg: 47 ± 15bpm).

What did the researchers conclude?The researchers concluded that even though theystandardized the total work done in each condition,there was a clear benefit of performing a highernumber of repetitions with a lighter load on heart rateand energy expenditure. This is almost certainlybecause they did not include bodyweight in the workdone calculation, and squats involve moving theweight of the body as well as the externally appliedload.

LimitationsThe study was limited in that work done was notactually standardized between conditions becausebodyweight was ignored. Also, energy expenditurewas estimated from heart rate, which is not asaccurate as some other methods.


The limiting joint during a failed squat – abiomechanics case series, by Flanagan, Kulik andSalem, in Journal of Strength & Conditioning Research(2015)

BackgroundThe back squat is an exercise performed with a barbellresting on the upper trapezius. It is the standardexercise for developing lower body strength and sizefor both athletes and bodybuilders. A great deal ofresearch has been performed into the back squat. Foran introduction to the squat exercise, please see thepreceding but one study review.

OBJECTIVE: To compare the joint angle movements(as measured using a motion analysis system),ground reaction forces, (as measured using a forceplate), net joint power and net joint work done (asestimated using inverse dynamics calculations)between successful 3RM squats and failed 3RM squats.

POPULATION: 18 young healthy adults, aged 26.6 ±4.29 years, of whom 5 failed to perform the finalrepetition of a set of 3RM barbell squats.

INTERVENTION: All subjects performed 3 repetitionsof a barbell squat with a 3RM load. Squats wereperformed to a vertical depth of 45% of leg length,which was approximately 90 degrees of knee flexion.Where subjects failed to complete the final repetitionof the 3RM set, the joint angle movements and thecalculated net joint moments and net joint work donewere compared between the failed and previouslysuccessful lifts.

What happened?

Net joint work and powerThe researchers found that the only significantdifference between the failed and successful squats inrelation to both net joint work and net joint poweroccurred at the hip. Net joint work and power weresignificantly lower in the failed squat than in thesuccessful squat. There was no evidence that anyother joint compensated by increasing either workdone or power output during the failed repetitions.

Individual differencesThe researchers observed that although there wasonly a significant difference between the failed andsuccessful squats in relation to net hip joint work doneand net hip joint power output, they did notice a trendtowards marked individual differences, with someindividuals displaying tendencies towards reducedwork done or power output at other joints, or smallcompensations.

What did the researchers conclude?The researchers concluded that the failure to completea squat repetition during a 3RM set might be linked tothe failure of an individual joint to produce sufficientwork done or power output. In many cases, this mightbe the hip joint, although they did report markedinter-individual differences.

LimitationsThe study was limited in that it was a case series andnot a controlled trial. Further investigations involvingdeliberately failed squats might yield interestingresults.


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/The_Limiting_Joint_during_a_Failed_Squat___A.96929.pdf

Effects of spine flexion and erector spinae maximalforce on vertical squat jump height – a computationalsimulation study, by Blache and Monteil, in SportsBiomechanics (2015)

BackgroundVertical jumping ability is a key athletic quality. Thus,researchers have assessed both the biomechanics ofvertical jumping and also the transfer of training tovertical jumping performance from several types ofcommonly-used training methods. Studies havereported beneficial effects on vertical jump heightfrom several training methods, including unilateralplyometrics, bilateral plyometrics, loaded jumps,unilateral conventional strength training, conventionalstrength and/or power training, isometric strengthtraining, Olympic lifting programs, kettlebell training,complex and contrast training, assisted and resistedjumps, and multiple combined methods. Studiesexploring the biomechanics of vertical jumping haveattempted to identify the key factors that contribute toincreased jumping performance. In this respect,previous studies have identified that co-ordination,strength, rate of force development and elastic energystorage through the stretch-shortening cycle can allinfluence vertical jump performance to some degree.Since vertical jumping ability is a key athletic qualitylike horizontal jumping ability, sprint running abilityand agility, a number of studies have assessed thecorrelations between each of these different qualities,with varying results, although generally with positivecorrelations in all cases.

OBJECTIVE: To assess the effects of spine flexion andmaximal isometric force of the erector spinae onmaximal vertical jump height during maximal verticalsquat jumps, by building a 2D computer model of themusculoskeletal system and simulating jumps withdifferent degrees of lumbar spine flexion and differentlevels of maximal isometric force of the erectorspinae.

POPULATION: 8 male athletes, aged 25.0 ± 4.2years.

INTERVENTION: The computer model simulationswere run based on the actual athlete performancesfrom 3 jumps, with 7 different degrees of lumbarspine flexion (between 20.1 and 71.6 degrees) and 5different levels of maximal isometric force of theerector spinae (between 5,600 and 8,600N) weretested. These combinations led to 35 different squatjump simulations.

What happened? The researchers found that vertical squat jump heightwas influenced by both the lumbar spine flexiondegree and by the level of maximal isometric force ofthe erector spinae. Lumbar spine flexion degreealtered vertical squat jump height by up to 9.4cmwhile the level of maximal isometric force of theerector spinae altered vertical squat jump height bymuch less: only up to 2.1cm. Specifically, increasingboth lumbar spine flexion angle and increasing thelevel of maximal isometric force of the erector spinaeincreased the vertical squat jump height.

What did the researchers conclude?The researchers concluded that increasing bothlumbar spine flexion angle and increasing the level ofmaximal isometric force of the erector spinaeincreased the vertical squat jump height duringcomputer model simulations. This may suggest thatincreasing erector spinae strength could be beneficialfor improving vertical jumping performance.

LimitationsThe study was limited by being a computer simulationand it is unclear whether actually increasing lumbarspine flexion angle or the level of maximal isometricforce of the erector spinae in living humans wouldindeed increase vertical squat jump height. Also, thelumbar spine flexion angle did not control for hipflexion angle and therefore there was a difference inthe position of the center of mass during the jumpsbetween the conditions that varied in lumbar spineangle.



Hamstring fatigue and muscle activation changesduring six sets of Nordic hamstring exercise inamateur soccer players, by Marshall, Lovell, Knox,Brennan, Siegler, and South, in Journal of Strength &Conditioning Research (2015)

BackgroundLike the quadriceps, the hamstrings muscle groupcomprises four individual muscles located on thethigh. However, the anatomy and muscle architectureof the hamstrings muscle group are much morecomplex than those of the quadriceps. There are threetwo-joint hamstring muscles that cross both the hipand the knee joints (which are the biceps femoris(long head), semimembranosus, and semitendinosus)and one single-joint hamstring muscle that onlycrosses the knee joint (the biceps femoris (shorthead)). The two-joint hamstring muscles all have theirorigin on the ischial tuberosity of the pelvis. Thesingle-joint hamstring muscle has its origin on thelower half of the linea aspera and the lateral condyloidridge. Thus, three of the hamstrings perform bothknee flexion and hip extension and one performs onlyknee flexion. Additionally, the hamstrings can bedivided into lateral and medial muscles. The lateralmuscles comprise the two heads of the biceps femoriswhile the semi-membranosus, and semitendinosus arethe medial muscles. The lateral muscles insert on thelateral condyle of the tibia and on the head of thefibula, while the medial muscles insert on the medialsurface of the tibia and on the medial condyle. Thebiceps femoris (long head) is the largest hamstring byanatomical cross-sectional area but the semi-membranosus is the largest by weight andphysiological cross-sectional area. The semitendinosushas the longest normalized fiber length whencompared to the other hamstrings while thesemimembranosus has the greatest pennation angle.Muscles with more complex pennation arrangementstend to have shorter normalized fiber lengths butlarger pennation angles and more fibers. Thesemitendinosus is the only hamstring muscle that isfusiform in shape. It has longitudinal muscle fibersthat are intersected by an intramuscular, tendinousseptum which separates the muscle into proximal anddistal regions. In contrast, the semimembranosus ishemi-pennate. The muscle fibers lie in a parallelarrangement, connecting the tendon at the origin onthe deep side and the tendon at the insertion on thesuperficial side of the muscle. The biceps femoris(long head) is also hemi-pennate. The muscle fiberslie in a parallel arrangement, connecting the tendon atthe origin on the deep side and the tendon at theinsertion on the superficial side of the muscle. Thebiceps femoris (short head) takes the form of atrapezoid, with longer muscle fibers on the proximalside and shorter ones on the distal side. Some groupsof researchers have suggested that the musclearchitectural arrangements of the hamstring musclesmay be important for identifying injury risk.

OBJECTIVE: To investigate the muscle activity of thebiceps femoris and of the medial hamstrings(measured using electromyography [EMG]) as well asknee flexion torque (using an isokinetic dynamometerto record torque in both concentric and eccentricphases at 30 degrees/s) during 6 sets of 5 repetitionsof the Nordic hamstring curl.

POPULATION: 10 amateur soccer players, aged 22.7± 3.9 years.

INTERVENTION: All subjects performed a single boutof 6 sets of 5 repetitions of the Nordic hamstring curl.

What happened?

Muscle activityThe researchers reported that mean and peak EMGactivity in the biceps femoris and medial hamstringsduring isokinetic testing did not change significantlythrough the 6 sets of Nordic curls. However, muscleactivity of both the biceps femoris and medialhamstrings was increased between 75 – 90 degrees ofknee flexion during the eccentric phase of Nordic curlsand reduced in the biceps femoris only between 45 –90 degrees of knee flexion during the concentricphase.

Isokinetic torqueThe researchers reported peak isokinetic concentricknee flexion torque reduced significantly after one setby 7.4%. No further reductions in peak isokineticconcentric knee flexion torque were observed. Therewere no reductions in peak isokinetic eccentric kneeflexion torque.

Isokinetic torque in each joint angle segmentThe researchers analyzed isokinetic concentric andeccentric knee flexion torques in 6 joint anglesegments of 15 degrees, between 0 and 90 degrees ofknee flexion. Isokinetic concentric and eccentric kneeflexion torques reduced in many of the joint anglesegments but no comparisons between segments werereported.

What did the researchers conclude?The researchers concluded that isokinetic concentricand eccentric knee flexion torque are reduced afteronly one set of Nordic hamstring curls. They alsoconcluded that hamstring muscle activity displayedrange of motion-specific and individual muscle-specificchanges during Nordic hamstring curls.

LimitationsThe study was limited as the researchers took a hugenumber of individual measurements across multiplemuscles, ranges of motion, and phases, whileassessing both muscle activity and torque. This makesit much more likely that some of the observationsmade were caused by chance.


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/Hamstring_fatigue_and_muscle_activation_changes.96932.pdf

Neuromuscular strategies contributing to fastermultidirectional agility performance, by Spiteri,Newton, Nimphius, in Journal of Electromyographyand Kinesiology (2015)

BackgroundRate of force development (RFD) or as it is moreaccurately termed where joint actions are beingmeasured, rate of torque development (RTD), is oftenused to describe the ability of the human musculo-skeletal system to perform rapid joint actions. It isgenerally measured as the torque developed overspecific intervals of time from the point of instigating ajoint action, typically in 10, 50 or 100ms incrementsup to around 250ms, at which point maximal torque isthought to be reached. The ability to move quickly isthought to be key for both athletic performance andfor function in elderly people. Indeed, it has beensuggested that RFD is more important than absolutestrength for athletes and, in support of this proposal,several studies have reported that higher athleticstatus (elite vs. sub-elite, starter or non-starter, orprofessional vs. non-professional) is associated withgreater RFD. Additionally, higher rate of forcedevelopment in lower body actions is generallycorrelated with faster sprint speeds and greaterjumping heights. This may indicate that increasingRFD is valuable for enhancing sprinting and jumpingabilities and/or that better athletes display greaterRFD. Various training methods have been assessed fortheir effects on RFD. It has been found that RFD canbe improved through long-term resistance trainingand the efficacy of such programs can be enhanced byheavy loads and faster bar speeds. The success of aresistance training program for improving RFD doesnot appear to be affected by muscle action, trainingvolume, or periodization model. However, concurrenttraining may be detrimental. Additionally, it has beenshown that RFD can be improved through long-termballistic training, Olympic weightlifting, plyometrics,balance training and combined programs. Ballistictraining appears to be superior to balance training butthe other methods seem equally effective. Themechanisms by which different training modalitiesaffect RFD are unclear. Surprisingly, the shifts inmuscle fiber type or type area (from type IIX to typeIIA) and increases in fascicle length (causing reducedmuscle stiffness) resulting from training very likelycause reduced RFD rather than increased RFD. On theother hand, increases in muscle stiffness, increases intendon stiffness, changes in proportional muscle fibertype area (from type I to type IIA), and increases inneural drive in the early phase (50ms) all very likelycontribute to increases in RFD with training. The exactexercises that are best for improving RFD in the lowerbody are unclear. In a recent acute trial, it was foundthat the box squat displayed greater external RFDthan traditional or powerlifting squats, suggesting thatthe box squat could be a useful lower-body exercisefor increasing RFD.

OBJECTIVE: To identify characteristics of femaleathletes possessing greater agility (as measured in amultidirectional agility test) and to assess muscleactivity of the leg muscles during the multidirectionalagility test using electromyography (EMG). The othercharacteristics measured included quadriceps muscle-cross sectional area (measured using ultrasound), rateof muscle activation and rate of force developmentduring an isometric mid-thigh pull.

POPULATION: 12 female basketball athletes, aged24.25 ± 2.55 years, allocated into fast (6 subjects)and slow (6 subjects) groups according to theirperformance in a multidirectional agility test.

INTERVENTION: All subjects performed a multi-directional agility test and an isometric mid-thigh pull.

What happened?

Characteristics of faster athletesThe researchers found that those athletes whodemonstrated superior performance in the multi-directional agility test displayed significantly lowerbody mass, significantly greater relative peak forceper unit cross-sectional area of the rectus femoris andvastus medialis, and significantly greater relativeisometric rate of force development (at both 90 and100ms) compared to slower athletes.

Characteristics of faster test performancesThe researchers found that the faster athletesdisplayed a significantly faster first change of directiontime, and a significantly faster decision time for thefirst directional change.

Muscle activity during agility testsThe researchers found that faster athletes displayedsignificantly greater rectus femoris and vastusmedialis pre-heel strike muscle activity in both firstand second directional changes, and significantlygreater pre-heel strike biceps femoris as well asmedial gastrocnemius muscle activity in the seconddirectional change compared to slower athletes.

What did the researchers conclude?The researchers concluded that when comparingathletes and their performances in a multidirectionalagility test, faster athletes displayed a faster firstchange of direction time and a faster first decisiontime compared to slower athletes. Faster athletes alsodisplayed lower body mass and higher rate of forcedevelopment. During agility test performances, fasterathletes displayed greater anterior leg muscle activity,which may be related to superior deceleration ability.

LimitationsThe study was limited in that it was cross-sectionaland it is unclear to what extent any of the variableswas involved in producing the differences in agilityperformance between subjects.



Residual force enhancement in humans: currentevidence and unresolved issues, by Seiberl, Power,and Hahn, in Journal of Electromyography andKinesiology (2015)

OBJECTIVE: To review the current literature that hasexplored the concept of residual force enhancement“in vivo” in humans.

The Review

IntroductionOur current model of how muscles produce force iscalled the sliding filament theory or alternatively thesliding filament and cross-bridge theory. Although thistheory can explain much of the behavior of musclefibers, it does not explain why they are able toproduce more force in an isometric or shorteningmuscle action that directly follows a lengtheningmuscle action, compared with a similar isometric orshortening muscle action that is carried out in totalisolation. This puzzling phenomenon is known as“residual force enhancement” and although it hasbeen extensively investigated, there is currently nosingle, obvious cause that can be used to provide acomplete explanation for its effects.

In vitro researchThe majority of research performed to investigate theresidual force enhancement phenomenon has to datebeen performed in vitro, using single muscle fibers orfascicles. The careful control that these study designsallow are very valuable, and they provide detailedinformation about the behavior of single muscle fibersexposed to a range of lengthening forces, durationsand excursions. Consequently, researchers have beenable to build up a detailed picture of the phenomenon.However, while these in vitro studies allow forsubstantial knowledge to be gained about the exactnature and about the underlying mechanisms of thephenomenon, they do not provide any informationregarding the relevance of the phenomenon under invivo conditions in humans.

In vivo researchThe researchers note that residual force enhancementhas been observed by many investigators to occur insub-maximal voluntary muscle actions ranging from10% to 100% of maximum voluntary isometriccontraction (MVIC) force and that the degree ofresidual force enhancement increases with theincrease in force production. The researchers note thatsuch studies were performed initially in small musclesand single-joint movements such as the fingers duringfinger abduction, progressed to larger muscles insingle-joint movements (ankle plantar-flexion andankle dorsiflexion), and was finally observed in thelargest, two-joint muscles (such as the knee extensorsand flexors). However, the researchers note that suchstudies have not yet established how meaningful theeffects of this phenomenon are during common, sub-maximal efforts such as walking, running, or jumping.

What did the researchers conclude?The researchers concluded that the phenomenon ofresidual force enhancement has been observed tooccur in vivo in all of the main lower-body musclesthat are involved in gait. However, the presence of thephenomenon during gait and the extent to which ithas a meaningful effect is unclear.

LimitationsThe study was limited in that it was a narrative reviewand was therefore based upon the opinions of theresearchers, which may not be the same as those ofall other researchers working in this field.



Acute changes in kinematic and muscle activitypatterns in habitually shod rear-foot strikers whilerunning barefoot, by Strauts, Vanicek, and Halaki, inJournal of Sports Sciences (2015)

BackgroundBarefoot walking and running have become morepopular in recent years, as the conceptual basis of theevolutionary discordance hypothesis has beenextended to other modern inventions, including thewearing of shoes. The evolutionary discordancehypothesis suggests that substantial departures fromthe nutrition and activity patterns of our hunter-gatherer ancestors are responsible for the chronicnon-communicable diseases of modern civilization,including obesity, type II diabetes, and cardiovasculardiseases. Researchers have explored several aspectsof the ways in which barefoot walking, running andjumping are different from the performance of thesame activities performed wearing shoes of variouskinds. Both performance-related and potentiallyinjury-causing biomechanical features have beenexamined. For example, it has been observed thatwhen jumping barefoot, greater relative peak powerand jump height are recorded during a vertical jumptest compared to when the same test is performedwith shoes. It has been suggested that the additionalcushioning provided by shoes allows force to bedissipated and not applied directly into the ground.Additionally, many studies have been performedexploring the differences between running barefoot,with shoes, and with minimalist footwear. Findings todate indicate that there are biomechanical differencesbut they are not exactly as expected and may beaffected by motor learning and by the running style(i.e. forefoot vs. mid-foot or rear-foot). For example,it has been found that peak tibial shock is significantlyhigher in a barefoot uninstructed condition than in ashod condition and in a barefoot instructed condition.The instruction appeared to be of great importance forreducing tibial shock when transitioning from shod tobarefoot running. Additionally, it has been found thataverage loading rate and maximal loading rate aresimilar in the barefoot and shod conditions duringtreadmill running, while average loading rate andmaximal loading rate are significantly higher whenheel striking condition than when forefoot striking forboth shod and barefoot conditions.

OBJECTIVE: To compare the joint angles and jointangle ranges of motion (ROM) (measured using a 14-camera motion analysis system) and muscle activities(measured using electromyography [EMG]) in barefootand shod running trials in habitually shod recreational,rear-foot striking runners. No instructions were givento the subjects regarding how to run during thebarefoot trials.

POPULATION: 6 recreational runners (4 male and 2female), aged 31.5 ± 9.9 years.

INTERVENTION: All subjects ran on an instrumentedtreadmill shod for 5 minutes, then performed 3 boutsof 10 minutes of barefoot running on the sametreadmill, and then completed a final 1 minute bout ofshod running, all at a self-selected pace.

What happened?

Joint angles at foot contactThe researchers found that all subjects continued torun in a rear-foot style when running barefoot. Theynoted that only the pelvis and hip joint angles at footcontact changed significantly between shod andbarefoot conditions. They observed that there wassignificantly less anterior pelvic tilt (by 3 degrees) andless hip flexion (by 4 degrees) in the barefootcondition than in the shod condition.

Joint angle ROMsThe researchers observed that the ROM for the trunk,pelvis, knee and ankle angles was lower in thebarefoot condition compared to the shod condition.

Muscle activityThe researchers observed that the muscle activity waslower for the biceps femoris, gastrocnemius, andtibialis anterior in the barefoot running conditioncompared to the shod condition. The reduction in thetibialis anterior muscle activity occurred predominantlyin the pre-activation phase and initial contact phases,while the reduction in the gastrocnemius lateralis andgastrocnemius medialis muscle activities occurredmainly in the push-off phase.

What did the researchers conclude?The researchers concluded that adopting barefootrunning leads to immediate reductions in pelvis andhip joint angles at foot contact, reductions in jointROM at the trunk, pelvis, knee and ankle, andreductions in the muscle activity of the biceps femoris,gastrocnemius, and tibialis anterior. The reasons forthese alterations in running style are unclear.

LimitationsThe study was limited in that it is unclear whetherthese changes to the running style are adaptive orbeneficial.



Effect of initial position on the muscle activity of thehip extensors and amount of pelvic tilt during pronehip extension, by Yoon, Lee, and An, in Journal ofPhysical Therapy Science (2015)

BackgroundHip extension is very probably the most importantjoint action in all of sports and is also key to beingable to perform functional activities of daily living.Although the hip joint is a ball-and-socket joint and iscapable of movement in every direction, hip extension(and flexion) is the joint action that occurs in thesagittal plane and facilitates the activities of walkingand running. Hip extension range-of-motion (ROM) isoften lost in injured or elderly people. Indeed, studieshave reported that hip extension ROM is the only formof hip ROM to decrease significantly with age and thata reduction in hip extension ROM occurs between the25 – 39 and 40 – 59 years age groups, which amountsto ~6 degrees over the whole 50-year duration ofadult life. Additionally, active hip extension ROM islower in elderly people who have a history of fallingcompared to elderly people who do not have a historyof falling. This may be because the lack of hipextension ROM makes it more difficult to solvemovement problems or it may be because reduced hipextension ROM leads to reduced hip extensionstrength: studies have found that a lack of hipextension ROM is associated with reduced hipextension strength and that mobilization of the hipjoint by a physical therapist can improve hip extensionstrength in subjects with normal hip extension ROM.In addition, lower back pain is correlated withsignificantly reduced hip extension ROM, irrespectiveof the knee flexion angle and hip abduction angle.However, studies have reported that the end ranges inthe frontal plane appear to produce the greatestproblems for lower back pain sufferers. In normalpeople, research indicates that hip extension ROM canvary widely. Some studies indicate that there issignificant hip extension ROM of ~15 – 20 degrees,while studies indicate that hip extension ROM is muchless. This may reflect large variability between groupsof subjects or it may be a function of differentmeasurement methods leading to varying results. Ofcourse, hip extension ROM is generally greater infemales than in males. However, it is important tonote that during combined forward hip and spineflexion actions, such as the sit-and-reach test, thereare also other sex differences in respect of the variousjoints. This makes combined flexibility tests like thesit-and-reach test problematic for assessing hipextension in populations comprising both males andfemales. Hip extension range-of-motion (ROM) fromthe neutral position, or hip hyper-extension, can besignificantly affected by the degree of hip abductionand knee flexion. Reducing knee flexion from 80degrees down to 0 degrees allows much greater hipextension ROM. Similarly, increasing the abductionangle of the hip allows for significantly greater hipextension ROM.

OBJECTIVE: To assess the effects of hip joint angleon the muscle activity of the erector spinae, gluteusmaximus and biceps femoris (as measured usingelectromyography [EMG]) and on the degree of pelvicanterior tilt (as measured using a motion analysissystem) during the prone hip extension exercise. Thiscaused different ranges of motion (ROM) to beperformed in each condition.

POPULATION: 15 healthy subjects, aged 26.7 ± 3.7years.

INTERVENTION: All subjects performed the dynamicprone hip extension exercise in 3 different startingpositions: 0 degrees (neutral), 20 degrees, and 45degrees of hip flexion.

What happened?

Muscle activityThe researchers found that erector spinae muscleactivity was significantly lower in the 45-degreecondition than in either the 0-degree or 20-degreeconditions. On the other hand, they found that bicepsfemoris muscle activity was significantly higher in the45-degree condition than in either the 0-degree or 20-degree conditions. Gluteus maximus muscle activitywas greater in the 20-degree condition than in eitherthe 0-degree or 45-degree conditions.

Anterior pelvic tiltThe researchers found that the degree of anteriorpelvic tilt was lower in the 20-degree condition than ineither the 0-degree or 45-degree conditions.

What did the researchers conclude?The researchers concluded that starting the prone hipextension in a position of 20 degrees of hip flexionleads to the greatest muscle activity in the gluteusmaximus and the smallest amount of anterior pelvictilt.

LimitationsThe study was limited as the researchers altered bothROM and joint angle and it is therefore unclear whichof these factors was responsible for the differences inmuscle activity observed.


Influence of pelvic position and vibration frequency onmuscle activation during whole body vibration in quietstanding by Kim and Seo, in Journal of PhysicalTherapy Science (2015)

BackgroundThe gluteus maximus originates on the posteriorquarter of the iliac crest, the posterior surface of thesacrum and coccyx and the fascia of the lumbar spine.It inserts on the oblique ridge on the lateral surface ofthe greater trochanter of the femur and the iliotibialband of the fascia latae. In humans, the gluteusmaximus is much larger than in other apes,particularly in respect of the upper region.Additionally, it is attached to the iliac crest as well asthe ischium, which is not the case in other apes. Also,in other apes, the gluteus maximus is subdivided intotwo separate muscles whereas in humans it is a singlemuscle, albeit with multiple subdivisions. Indeed, thegluteus maximus contains 3 divisions from top tobottom (superior, middle, inferior) and two halvesfrom side to side (medial and lateral) that can beshown to perform distinctly different functions in 6regions, as can be shown by both muscle architectureand electromyography (EMG) activity. The gluteusmaximus can also be subdivided into superficial, deepsacral and deep iliac layers. The gluteus maximus isan extremely important muscle and is the largest andheaviest of all the muscles in the body. It comprisesaround 13 – 15% of total leg muscle mass by weight(around 600g in elderly males). It has a physiologicalcross-sectional area of ~34cm2 and an anatomicalcross-sectional area of ~ 48.4cm2. The musclearchitecture of the gluteus maximus is extraordinaryin that it has both a long fascicle length and a largecross-sectional area. It is also strongly pennate, asmight be expected from its large cross-sectional area.The gluteus maximus is 52 – 68% percent type Ifibers, making it an evenly mixed slow and fast twitchmuscle. It has its most significant moment arm in thesagittal plane for hip extension but also has a largemoment arm in the transverse plane for externalrotation. It also has a very small adduction momentarm in the frontal plane. Our current understandingbased on anatomy, muscle architecture and EMGstudies indicates that the gluteus maximus performs anumber of different hip actions from extension, toexternal rotation and abduction/adduction. It alsoraises the trunk when the femur is fixed in position,and posteriorly tilts the pelvis. The gluteus maximustherefore requires a range of different movementsperformed with these actions in mind in order totarget it fully. Various pathologies have beenassociated with gluteus maximus weakness. A weakgluteus maximus has been associated with anincreased risk of lower back pain, excessive anteriorpelvic tilt, sacroiliac joint pain, piriformis syndrome,anterior femoral hip glide, knee valgus and increasedACL injury risk and hip internal rotation andconsequent foot pronation.

OBJECTIVE: To assess the effects of pelvic positionand frequency of whole body vibration (WBV) duringquiet standing on the muscle activity of the uppertrapezius, rectus abdominis, external obliques, erectorspinae, gluteus maximus, rectus femoris, semi-tendinosus, and medial gastrocnemius (as measuredusing electromyography [EMG]).

POPULATION: 18 healthy subjects (9 males and 9females), aged 27.7 ± 4.1 years.

INTERVENTION: The subjects performed quietstanding on a WBV platform while three frequencies ofWBV were tested (0Hz, 10Hz, and 20Hz) and while thesubjects assumed 3 different pelvic positions (neutral,anterior tilt, and posterior tilt).

What happened? The researchers found that muscle activity of almostall muscles was increased significantly with increasingfrequency of WBV. They also noted that muscleactivity of almost all muscles was significantly greaterduring both anterior and posterior pelvic tilt comparedto neutral pelvic tilt. Also, posterior pelvic tilt generallyinvolved greater muscle activity than anterior pelvictilt.

What did the researchers conclude?The researchers concluded that posterior pelvic tiltand higher WBV frequency were associated withgreater muscle activity during quiet standing.

LimitationsThe study was limited in that it is unclear to whatextent the findings can be extrapolated to other bodypositions.



3. ANATOMY, PHYSIOLOGY, AND NUTRITION


Autophagic adaptation is associated with exercise-induced fibre-type shifting in skeletal muscle, by Tam,Pei, Yu, Sin, Leung, Au, and Siu, in Acta Physiologica(2015)

BackgroundMuscle fibers can be classified in various ways andusing different methods. Firstly, the method ofmeasurement can differ and involve either ATPasehistochemistry, immunohistochemistry, or (much lesscommonly) metabolic enzymes. Secondly, either theproportion of muscle fibers (also variously referred toas the percentage or composition) or the cross-sectional area of the muscle fibers can be measuredfor each muscle fiber type. Since the cross-sectionalarea of the individual muscle fibers differs betweenmuscle fiber types, each of these measurementsproduces different results and describes differentunderlying phenomena. Changes in the proportion ofmuscle fibers is thought to reflect a conversion of onetype of muscle fiber (usually a hybrid type) to another(usually a pure type I, IIA or IIX). Changes in fibercross-sectional area reflect a combination of bothchanges in individual fiber cross-sectional area andconversions of one type of muscle fiber to another.Thirdly, results can be presented in absolute terms orin proportional terms relative to the other muscle fibertype areas, with each muscle fiber type area beingexpressed as a percentage of the whole. Presentingchanges in cross-sectional area in absolute termsgenerally shows that all muscle fiber type areaschange (because they all increase). Presentingchanges in cross-sectional area in proportional termsgenerally shows that no muscle fiber type areaschange (because they all increase more or less to thesame extent). Muscle fiber type is thought to beimportant for several reasons. Firstly, muscle fibertype is thought to influence the strength-to-size ratioof individual muscles (also called specific tension).Type II muscle fibers are generally believed to displaya higher force than type I muscle fibers, although theliterature is actually conflicting in this regard.Secondly, muscle fiber type is thought to affect musclecontraction velocity. Indeed, it has consistently beenfound by many investigators that type II muscle fibersdisplay a faster muscle contraction velocity than type Imuscle fibers. Knowledge of how training affects typeI and type II muscle fibers may therefore be importantfor strength coaches and athletes, as a higherproportion of type II muscle fibers is likely beneficialfor performance in strength and power sports. Thirdly,muscle fiber type may be important for hypertrophyprogramming. It has traditionally been accepted thattype II muscle fibers tend to increase to a greaterextent in cross-sectional area than type I musclefibers following a program of resistance training.However, it has been suggested that observations ofgreater hypertrophy in type II muscle fibers couldpotentially be more a function of the type of resistancetraining programs that are conventionally used tostudy increases in cross-sectional area than of theresponsiveness of this particular muscle fiber type.

OBJECTIVE: To assess whether long-term aerobicexercise would affect basal autophagic musclesignaling (as measured by quantitative real-timepolymerase chain reaction analysis of samples takenfrom the plantaris and gastrocnemius muscles) and tofind out if there is an association between autophagyand shifts in muscle fiber type (as measured byimmunohistochemical staining), in both cases using arodent model.

POPULATION: 16 adult female Sprague-Dawley rats(age = 2 months; weight = 172 ± 4g), randomlyallocated either to a control or an exercise group.

INTERVENTION: The rats in the exercise group werekept in cages equipped with running wheels thatenabled them to perform habitual exercise at will for20 weeks. The rats in the control group were cagedwithout running wheels.

What happened?

Running distancesThe rats in the exercise group ran approximately4,000m per day (e.g. weeks 1 – 4 mean daily runningdistance = 4,170 ± 764m).

Autophagic muscle signalingThe researchers found that the results of theirquantitative real-time polymerase chain reactionanalysis suggested that there was greater basalautophagy in the plantaris muscle of the exercisegroup, as indicated by elevated LC3-II levels, whichwere associated with shifts in muscle fiber type of thesame muscle.

Muscle fiber type shifts and hypertrophyThe researchers found that the exercise groupdisplayed a smaller proportion of type IIX fibers and agreater proportion of type IIA muscle fibers than thecontrol group. However, type I and type IIB musclefibers were not different. This suggests that theexercise caused a shift from type IIX to type IIA butleft type I and type IIB muscle fibers unchanged. Inaddition, the researchers noted that the muscle cross-sectional area of type I, type IIA, and type IIB fibersof the plantaris muscle were significantly greater by16.8%, 13.8% and 17.4% respectively, in the exercisegroup compared to the control group. Similarly, themuscle cross-sectional area of type I, type IIA, andtype IIB fibers of the gastrocnemius muscle weresignificantly greater by 38.7%, 20.0% and 31.4%,respectively, in the exercise group compared to thecontrol group.

What did the researchers conclude?The researchers concluded that exercise causesincreased basal autophagy, which was associated withthe exercise-induced shifts in muscle fiber type.

LimitationsThe study was limited in that it was performed inrodents and it is unclear whether the same resultswould be observed in humans.


http://onlinelibrary.wiley.com/doi/10.1111/apha.12503/full

Capillary growth, ultrastructure remodelling andexercise training in skeletal muscle of essentialhypertensive patients, by Gliemann, Buess, Nyberg,Hoppeler, Odriozola, Thaning, and Mortensen, in ActaPhysiologica (2015)

BackgroundHypertension is defined as blood pressure above acertain level. In other words, hypertension is high orelevated blood pressure. Blood pressure is typicallyquoted in two numbers: systolic and diastolic, whichreference a blood pressure expressed in mmHg.Systolic blood pressure is the pressure in the arterywhen the heart is in systole (i.e. when the heart iscontracting) and diastolic blood pressure is thepressure in an artery when the heart is in diastole (i.e.when the heart is relaxed). Therefore, systolic bloodpressure is much higher than diastolic blood pressure.Blood pressure is graded into several categories, asfollows: optimal, normal, high-normal, grade 1hypertension (mild), grade 2 hypertension (moderate)and grade 3 hypertension (severe). The upper andlower bounds of the systolic and diastolic bloodpressures for each of the non-hypertensive gradesare: <120/<80, 120 – 129/80 – 84, and 130 – 139/85– 89. The upper and lower bounds of the systolic anddiastolic blood pressures for each of the hypertensivegrades are: 140 – 159/90 – 99, 160 – 179/100 – 109and >180/>110. Formally, hypertension is defined asan average systolic blood pressure of >140mmHg,diastolic blood pressure of >90mmHg, or the use ofantihypertensive medication. High blood pressure orhypertension are widely regarded as very significantrisk factors for cardiovascular disease in general andcoronary artery disease in particular. Overall, theresearch indicates that lowering blood pressure in thegeneral population and in at-risk groups, such asthose with coronary artery disease and chronic kidneydisease, is clearly associated with lower all-causemortality. Whether lowering blood pressure in the veryold is also associated with lower all-cause mortality ismuch less clear. Hypertension is a significant dangerto public health in many countries in the developedworld. The worldwide prevalence of hypertension inadult populations is around 26% but can range from 4– 73% depending upon the gender and geography ofthe individuals being tested. Key risk factors forhypertension include low levels of cardiovascularfitness and low levels of physical activity, as well as anolder age, greater alcohol consumption, a higher bodymass index (indicating overweight or obesity), a highwaist circumference, any sleep-related breathingdisorders, and short sleep duration. The influence ofdiet is difficult to assess. Fortunately, exercise iseffective for reducing hypertension in otherwisehealthy individuals. In general, research involvingexercise interventions as short as 4 weeks hasreported significant reductions in systolic and diastolicblood pressures of around 3 – 5mmHg.

OBJECTIVE: To compare the capillary shape anddensity in subjects with and without hypertension (bytaking muscle biopsies from the vastus lateralis andexamining the samples with a transmission electronmicroscope) and to see whether exercise alterscapillary shape and density similarly or differently inthese subjects.

POPULATION: 21 subjects (10 with hypertension:systolic = 183 ± 7; diastolic = 101 ± 5 mmHg; 11without hypertension: systolic =142 ± 5; diastolic =74 ± 3mmHg).

INTERVENTION: All subjects performed 1 hour ofaerobic exercise on the cycle ergometer, 3 – 4 timesper week, for 8 weeks.

What happened?

Differences between subjects at baselineThe researchers found that capillary density did notdiffer between the groups with hypertension andwithout hypertension (553 ± 58 vs. 462 ± 39capillaries per mm2). Similarly, they found that thecapillary-to-muscle fiber ratio was not significantlydifferent between the groups with hypertension andwithout hypertension (1.65 ± 0.1 vs. 1.64 ± 0.1times). However, they found that the subjects withhypertension had a significantly lower capillary area(12.7 ± 0.4 vs. 13.9 ± 0.2lm2) and displayed non-significantly thicker capillary basement membranes(399 ± 16 vs. 358 ± 13 nm) compared to the subjectswithout hypertension.

Differences between subjects as a result of trainingThe researchers found that capillary-to-fiber ratioincreased significantly in the hypertensive subjects butnot in the non-hypertensive subjects (15% vs. 10%).The researchers also noted that capillary area andcapillary lumen area were increased by 7% and 15%in the hypertensive patients, while capillary basementmembrane thickness decreased by 17%. No changesin these parameters occurred in the non-hypertensivegroup.

What did the researchers conclude?The researchers concluded that hypertensive subjectshave a significantly lower capillary area and may alsohave thicker capillary basement membranes. Inaddition, they concluded that exercise training appearsto benefit capillary shape in hypertensive individualsto a greater extent than non-hypertensive individuals,causing increased capillary-to-fiber ratio, capillaryarea, and capillary lumen area and reduced capillarybasement membrane thickness.

LimitationsThe study was limited in that it is unclear whetherthese beneficial changes in the hypertensive subjectsare the mechanism by which exercise improveshypertensive symptoms.


http://onlinelibrary.wiley.com/doi/10.1111/apha.12501/pdf

Effects of resistance exercise timing on sleeparchitecture and nocturnal blood pressure, by Alley,Mazzochi, Smith, Morris, and Collier, in Journal ofStrength & Conditioning Research (2015)

BackgroundSleep is essential for humans. Sleep deprivation leadsto severe reductions in both cognitive and physicalperformance and ultimately endangers health. Currentguidelines for health recommend that adults achievebetween 7 – 9 hours of sleep each night. However,several epidemiological studies have revealed thatachieving inadequate sleep is a common problem formany adults of all ages in modern society, as well aschildren. In this regard, many researchers have madesuggestions regarding potentially contributory factorsto the failure to attain sufficient sleep in modernsociety, including caffeine consumption, smoking,exposure to electronic media, exposure to bright lightsduring dark night hours, sleep timing, jet lag and shiftwork, all of which may disrupt our natural circadianrhythms and thereby alter sleep. The relatively highprevalence of short sleep duration among adults inmodern society has also been associated with the risein obesity and overweight. Indeed, a number of cross-sectional studies have identified an associationbetween shorter sleep durations and conditions ofeither obesity or overweight. Whether this implies thatsleeping for shorter sleep durations leads to increasedappetite or food consumption, or whether being obeseor overweight leads to sleeping for shorter durations,is unclear. Interestingly, intermittent sleep has alsobeen connected to greater risk of being overweight orobese, and a single randomized controlled trial hasfound that placing a sleep management componentinto a 12-week weight-loss intervention program ledto significantly more weight loss in adults than astandard treatment, as well as greater coping andself-efficacy measures. These factors suggest thatshort sleep duration might lead to overweight orobesity rather than the other way around. Researcherswho have investigated the impact of interventions onsleep have suggested that effective measures forimproving sleep duration and quality include: keepingconsistent bedtimes and consistent waking times,engaging in regular physical activity and exercise,reducing consumption of caffeine (notably post-lunch),reducing exposure to television programs and videogames immediately before bedtime, turning off allelectronic displays 2 hours prior to bedtime, dimmingoverhead lights later in the evening, making use of hotbaths, soothing drinks, meditation, massage, deepbreathing, reading calming material, minimizing theimpact of distracting noise (either by reducing allnoise or by implementing white noise generators suchas electric fans), and ensuring that the bedroom is ata suitable temperature and the bed is comfortable.

OBJECTIVE: To assess the effects of the timing of aresistance training workout on the time taken to fallasleep and number of times woken during the night(as measured using a sleep-monitoring device) andnocturnal blood pressure.

POPULATION: 24 sedentary or recreationally activeindividuals, aged 20 ± 0.3 years.

INTERVENTION: All subjects performed a single 30-minute resistance training workout on 3 differentoccasions at 3 different times of day: 0700 hours,1300 hours, and 1900 hours. The resistance trainingworkout comprised 3 sets of 10 repetitions at 65% of10RM on the following machines: leg press, kneeextension, leg curl, calf raise, abdominal crunch,triceps extension, biceps curl, lat pulldown, and chestpress.

What happened?

Sleep characteristicsThe researchers found that when performing theresistance training workout at 0700 hours, thesubjects took a significantly shorter time to fall asleepthan when performing the same workout at 1300hours and 1900 hours (36 ± 5.2 vs. 57 ± 7.1 vs. 71 ±13.1 minutes). Interestingly, the researchers foundthat all resistance training workouts caused thesubjects to experience significantly fewer times wokenduring sleep bout compared with the control (0700hours: 3 ± 0.5; 1300 hours: 2 ± 0.5; 1900 hours: 2 ±0.5; control: 4 ± 0.8 times woken).

Nocturnal blood pressureThe researchers found that the timing of resistancetraining workouts had no effect on nocturnal bloodpressure.

What did the researchers conclude?The researchers concluded that the timing of whenresistance training workouts are performed can affectthe time taken to get to sleep, with resistance trainingperformed closer to sleep leading to longer timestaken to get to sleep. However, they also found thatperforming resistance training appears to lead tofewer times woken during sleep than a non-trainingcontrol condition and that it does not affect nocturnalblood pressure.

LimitationsThe study was limited in that it is unclear whether thesame results would be observed in trained or morephysically active populations.



Cardiovascular adaptation and remodeling to rigorousathletic training, by Weiner, and Baggish, in Clinics inSports Medicine (2015)

OBJECTIVE: To provide a review describing theprocess and effects of exercise-induced cardiacremodeling.

The Review

IntroductionDuring exercise, there is a requirement for oxygenthat increases with increasing workload. The need formore oxygen is met by an increased intake of air intothe lungs, by means of a faster respiratory rate.Inspired oxygen passes from the lungs into the bloodand is then driven around the body via the arteries bythe pumping actions of the heart. As the need foroxygen increases, heart rate also increases. Althoughheart rate is a good measure of the activity of theheart during exercise, a more precise measure iscardiac output, which is the number of liters of bloodpumped around the body each minute. It can becalculated as the product of heart rate and strokevolume. Stroke volume is the amount of blood thatcan be pumped with a single heart beat. The size ofthe stroke volume seems to be dependent upon thesize of the heart muscle and the size of the cardiacchambers in which the blood is stored prior to beingpumped around the body. The cardiac chamberscomprise four different, main parts: the left and rightatria and ventricles. The right atrium receives oxygen-depleted blood from the main circulatory system andthen passes it into the right ventricle. The rightventricle pumps oxygen-depleted blood up to thelungs, where it receives oxygen and returns to the leftatrium. The left atrium passes blood into the leftventricle, where it is pumped around the maincirculatory system and returns to the right atrium.

Left ventricleThe researchers explain that aerobic exercise is knownto lead to enlargement of the left ventricle of the heartmuscle. The left ventricle is the chamber of the heartthrough which blood flows last before being ejectedaround the body. They note that the increase in leftventricle size that occurs is also accompanied by anincrease in the thickness of the left ventricle wall,which is mainly comprised of muscle and thereforefunctions to help drive the blood around the body as itleaves the left ventricle. They note that while thisthickening is sometimes noted in athletes withoutaccompanying increases in the size of the chamber,this tends to be in strength and power athletes ratherthan endurance athletes.

Right ventricleThe researchers explain that aerobic exercise has alsobeen found to cause enlargement of the right ventricleof the heart muscle, although this fact is less well-known. The right ventricle is responsible for ejectingblood around the much smaller circulatory system thatinvolves the lungs, where the oxygen-depleted bloodis replenished and then returns to the heart ready to

be pumped to the rest of the body. The researchersnote that in the case of the right ventricle, there is anincrease in size of the chamber but little increase inthe thickness of the muscular walls. They also notethat the increase in right ventricle size is usuallyclosely related to increases in size of the left ventricleand any asymmetric growth in the two chambersmight be a signal of a pathology rather than a naturaladaption to training.

Left and right atriaThe researchers note that a small number of studiesover a long period of time have suggested thatendurance athletes have larger left atria thansedentary controls and that this may imply that someremodeling of the atria occurs with aerobic exercise.They note that more recent studies have now reportedsimilar findings for the right atrium as well.

AortaThe aorta is the main artery leading out of the leftventricle. The researchers note that recent meta-analyses assessing the aortic root diameter in athletesand non-athletes has found that it is an average of 1.6– 3.2mm larger in athletes than in non-athletes,depending on the point of measurement. However, itis unclear whether this enlargement is greater instrength and power athletes or in endurance athletes.

What did the researchers conclude?The researchers concluded that exercise-inducedcardiac remodeling is a complex process that followsdirectly from the stresses of increased pressure andvolume resulting from the elevated cardiac outputassociated with heightened oxygen demand. Theyconcluded that in addition to the well-known changesin left ventricular size and wall thickness, there arealso adaptions in the right ventricle, both right and leftatria, and the aorta. They note that the extent towhich these changes are always adaptive and thepoint at which they become pathological is unclear.

LimitationsThe study was limited by being a narrative review andwas therefore based upon the opinions of the authors,which may differ from other researchers working inthe field. Also, the research literature was very limitedand further work may reveal different findings.



Alterations of gut barrier and gut microbiota in foodrestriction, food deprivation and protein-energywasting, by Genton, Cani, and Schrenzel, in ClinicalNutrition (2015)

OBJECTIVE: To perform a narrative review describingthe impact of caloric restriction on the structure andfunction of the gut.

The Review

Intestinal permeabilityIntestinal permeability is the extent to which passivediffusion of molecules can occur across the intestinalwall. It is assessed in humans by providing orally-administered sugars and then later measuring therecovered levels in urine. Specifically, small bowelpermeability has classically been measured by takingthe ratio of the fractional urinary excretion of a large-size sugar like lactulose to a small-size sugar likemannitol. A high ratio on this measurement suggeststhat the small bowel is highly permeable.

Effects of protein restrictionThe reviewers explain that a small number of animalstudies have explored the effects of protein restrictionon gut structure and intestinal permeability. Suchstudies have reported alterations in rodents, includingreduced bodyweight, reduced jejunal villi and laminapropria heights, decreased hepatic and jejunal levelsof glutathione, decreased secretory IgA levels, as wellas reduced quantities of intraepithelial lymphocytes.These findings are difficult to interpret, however.

Effects of caloric restrictionThe researchers explain that animal studies haveclearly shown that calorie restriction increases smallbowel permeability and whole bowel intestinalpermeability. They also noted that states of cachexia(severe muscle loss) have been shown to be closelyassociated with increased whole gut permeability. Inhumans, the researchers note that a complete fastingperiod of 36 hours does not appear to increaseintestinal permeability but does lead to reducedintestinal absorption. However, in cases of long-termcaloric restriction, elevated small bowel permeabilityhas not been observed and therefore it seems thateven small amounts of food are able to avert theseeffects.

Gut-associated lymphoid tissue (GALT)The researchers explain that the GALT is the largestsingle mass of immune cells in the human body andcontains lymphocytes in the Peyer's patches, laminapropria and intestinal epithelium, as well as M cells,granulocytes, macrophages and mast cells. Theseimmune cells may respond to certain of the items thatpass the gut wall and cause inflammation.

Effects of caloric restriction on immune functionThe researchers note that protein or caloric restrictionand subsequent muscle loss appears to be associatedwith an inflammatory state in humans, as indicated byhigh serum levels of IL-6 and C-reactive protein andreduced activation of lamina propria lymphocytes and

enterocytes, and increased levels of pro-inflammatorycytokines, possibly caused by increased intestinalpermeability.

Effects of caloric restriction on gut microbiotaThe researchers note that very few studies haveassessed the relationship between caloric restrictionand gut microbiota. However, it appears that caloricrestriction in rodents leads to reduced and alteredmicrobiotic count in various parts of the intestine.

What did the researchers conclude?The researchers concluded that caloric restriction andsubsequent muscle loss affects gut structure andintestinal permeability, GALT, and the gut microbiota.However, they concluded that the research is stilllimited and the mechanisms by which these differentfactors interact are difficult to unravel.

LimitationsThe study was limited by being a narrative review andwas therefore based upon the opinions of the authors,which may differ from other researchers working inthe field. Also, the research literature was very limitedand further work may reveal different findings.



Effects of high-intensity intermittent exercise trainingon appetite regulation, by Sim, Wallman, Fairchild,and Guelfi, in Medicine & Science in Sports & Exercise(2015)

BackgroundInterval training was first developed by track and fieldathletes in the middle of the last century to helpimprove middle- and long-distance runningperformance. Track running performance, likeperformance in other endurance sports, is dependentupon three main physiological factors: aerobiccapacity, lactate threshold, and work economy.Together, these variables can explain the largemajority of the difference in endurance performancebetween individuals in both heterogenous (varied) andhomogenous (similar) groups. In contrast, each of thevariables alone is only able to explain the majority ofthe difference in endurance performance between theindividuals in heterogenous groups. Aerobic capacity ismeasured using VO2-max, which is the volume ofoxygen that the body can take in and use effectively ina given period of time, usually measured relative tobodyweight as ml/kg/min. Lactate threshold ismeasured by reference to blood lactate. During anincremental exercise test, blood lactate initiallyremains close to its resting value. At a certain exerciseintensity, however, it rises above the resting value andthis exercise intensity is called the lactate threshold.Running economy (strictly work economy if includingother exercise modalities) is a measurement of theefficiency of the athlete. Economy is most commonlydescribed in terms of how much oxygen it takes to runa given distance at a given speed. Traditionally, theexclusive method for developing enduranceperformance was steady-state exercise. Indeed,researchers have found that steady-state exercise canimprove endurance performance in untrainedindividuals. However, improvements in already well-trained individuals are small. Consequently, studiesexploring the effects of steady-state exercise intrained subjects have often failed to find significantincreases in endurance performance or in any of theunderlying physiological factors (aerobic capacity,lactate threshold, and work economy). More recently,high-intensity interval training (HIT) has beendeveloped as a tool for increasing enduranceperformance. HIT can be broadly defined as repeated bouts of short-to-moderate duration exercise (i.e. 10seconds to 5 minutes) at an intensity greater than theanaerobic threshold. These exercise bouts are dividedby short bouts of either low-intensity work orinactivity that allow either a partial or a full recovery.Researchers have found that HIT can improveendurance performance in untrained individuals. Theincreases are often larger than those following fromsteady-state interventions of similar duration.Moreover, research has often found significantincreases in endurance performance in trainedindividuals following HIT exercise interventions.

OBJECTIVE: To compare the effects of 12 weeks ofsteady-state exercise and HIT on appetite regulation(as measured by ad-libitum energy intake from alaboratory test meal after both high and low pre-loadmeals, self-perception of appetite, and appetite-related blood markers, including leptin, insulin, activeghrelin, PP and PYY).

POPULATION: 30 overweight, sedentary males (BMI= 27.2 ± 1.3 kg/m2)), aged 31± 8 years, randomlyallocated to either HIT or steady-state exercisegroups, or a non-exercising control group.

INTERVENTION: Both training groups performed 3workouts per for 12 weeks, using a cycle ergometer.The HIT group performed intervals of 15 seconds at apower output of 170% VO2-max with 60 seconds ofactive recovery. The steady-state group performedcontinuous exercise at 60% of VO2-max. Both groupsperformed the same workload.

What happened?

Ad-libitum energy intakeThe researchers found that at baseline, there was nosignificant difference in the ad-libitum energy intakeafter the high or low pre-load meals in either the HITor steady-state groups (-43 ± 585 vs. 219 ± 523kJ).This indicates that the subjects did not adjust their ad-libitum energy intake for the amount of energy takenin during the pre-load meal. Additionally, after theintervention, there was similarly no difference in thesteady-state group (-68 ± 677kJ) but there was areduction in the HIT group (-516 ± 395kJ). Thisindicates that the HIT group were better able toregulate their appetite in relation to calories alreadyconsumed, after the intervention.

Perception of appetiteThe researchers found that neither of the exerciseinterventions had any effect on perceived hunger,fullness, satiation, desire to eat, or prospective foodconsumption.

Appetite-related blood markersThe researchers found that insulin in the fasted statewas reduced after the HIT intervention and that insulin60 minutes post-meal was reduced in the steady-stateintervention. They noted that leptin levels werereduced after the HIT intervention but not after thesteady-state intervention. There were no changes inghrelin, PP, PYY, or blood glucose.

What did the researchers conclude?The researchers concluded that HIT seems to helpregulate appetite in overweight males.

LimitationsThe study was limited in that it is unclear whether thesame results would be seen in normal weight orfemale populations.


http://europepmc.org/abstract/med/25899101

Effects of resistance training with and without caloricrestriction on physical function and mobility inoverweight and obese older adults, by Nicklas,Chmelo, Delbono, Carr, Lyles, and Marsh, in TheAmerican Journal of Clinical Nutrition (2015)

BackgroundObesity arises from an individual being in a chronicallypositive energy balance (i.e. where energy intake isgreater than energy expenditure). However, themechanisms by which this chronically positive energybalance arises are unclear and it is thought to involvegenetic, environmental and cultural influences and therising standard of living in the developed world.Globally, obesity and overweight is now the mainnutr it ional problem. Obesity has surpassedmalnutrition and infectious disease as the mostimportant contributor to mortality and ill health. TheWorld Health Organization (WHO) have reported thatworldwide obesity has nearly doubled since 1980 andthat as of 2008, >1.4 billion adults aged >20 yearswere overweight of which >0.5 billion were obese.This means that 35% of the world population aged>20 years were overweight and 11% were obese.Obesity and overweight are often defined by referenceto Body Mass Index (BMI), where overweight isdefined as a BMI of >25kg/m2 and obesity is definedas a BMI of >30kg/m2. The WHO have identified thathaving a higher BMI puts individuals at increased riskof a number of non-communicable diseases, includingcardiovascular diseases (mainly heart disease andstroke), type II diabetes, osteoarthritis, and somecancers (endometrial, breast, and colon). Additionally,the risk of incurring these diseases has been found toincrease further as BMI increases. The major riskfactors for obesity are: a high amount of sedentarybehavior and other inactive lifestyle behaviors such astelevision watching, ethnicity and socioeconomicstatus, and poor nutritional habits. There is thereforegreat interest from healthcare organizations,governments and research bodies in identifying thebest methods for reducing the incidence andprevalence of obesity and overweight. In themainstream media, the most common weightmanagement methods are dietary interventions andexercise/lifestyle programs. However, in the medicalenvironment and particularly for those individuals whoare very or morbidly obese, there are other treatmentoptions, including bariatric surgery. Nevertheless, alarge and detailed previous body of research hasfound that dietary interventions and exercise/lifestyleprograms are indeed beneficial to obese individuals forimproving cardiovascular risk, reducing intra-hepaticlipids, and decreasing subcutaneous and visceral fat.Moreover, such studies have also reported that greaterlevels of physical activity may benefit weight loss andminimize the risk of regaining lost weight. In contrast,bariatric surgery has been associated with excessivelosses in lean body mass, which may lead tosarcopenia in later life.

OBJECTIVE: To assess the effects of caloric restrictionon the adaptations to resistance training in elderlyoverweight and obese adults. Adaptions includedmuscular strength (as measured primarily by maximalisokinetic knee extension torque), body composition(by reference to whole-body fat and lean mass, andbody fat percentage measured using dual-energy X-ray absorptiometry [DEXA]), and functional status (asmeasured by usual gait speed, chair rise time, shortphysical performance battery (SPPB) score, 400mwalk time, and self-reported disability).

POPULATION: 126 elderly overweight and obesemales and females, randomly assigned to either acaloric restriction (63 subjects, aged 69.6 ± 3.9 years,BMI: 30.4 ± 2.2kg/m2) or calorie neutral (63 subjects,aged 69.4 ± 3.6 years, BMI: 30.7 ± 2.4kg/m2)condition.

INTERVENTION: All subjects performed a 3-day perweek resistance-training intervention involving 3 setsof 10 repetitions with 70% 1RM of the leg press, legextension, seated leg curl, seated calf raise, inclinepress, compound row, triceps press, and bicep curlexercises. The caloric restriction group received anintervention comprising meal replacements, nutritioneducation, and dietary behavior modification advice inweekly meetings with a dietician, aimed at producinga caloric deficit of 600kcal per day over the course ofthe 5-month trial.

What happened?

Muscular strengthThe researchers found that the increase in kneeextension torque that resulted from the resistance-training program was similar in both the calorieneutral and calorie restricted groups (16.4 ± 21.9 vs.12.3 ± 14.8Nm).

Body compositionThe researchers found many differences betweengroups in relation to body composition. The caloricrestriction group lost more total body mass (-4.9 ±3.9kg vs. -0.1 ± 2.2kg), fat mass (-3.6 ± 2.8kg vs.-0.6 ± 1.5kg), lean body mass (-1.1 ± 1.6kg vs. 0.3± 1.3kg), and body fat percentage (-2.2 ± 1.9% vs.-0.6 ± 1.2%).

Functional statusThe researchers found that improvements in functionalstatus did not differ between groups in respect ofusual gait speed, chair rise time, SPPB score, 400mwalk time, and self-reported disability.

What did the researchers conclude?The researchers found that although caloric restrictioncaused adverse effects on lean mass gain, it did notaffect the improvements in strength or functionalstatus achieved through resistance training.

LimitationsThe study was limited in that it did not include afollow-up and it is unclear how long these beneficialeffects might last.


http://ajcn.nutrition.org/content/101/5/991.short

Oxytocin reduces caloric intake in men, by Lawson,Marengi, DeSanti, Holmes, Schoenfeld, and Tolley, inObesity (2015)

BackgroundObesity and overweight are rapidly rising phenomenaworldwide and are both important contributors tomortality and ill health. Weight loss is the primarytechnique for addressing both of these conditions.Weight loss is essentially achieved by means ofaltering the balance between the amount of caloriesconsumed and expended. At its most basic, therefore,weight loss can be achieved either by reducingcalories consumed, increasing calories expended, or acombination of both. However, there are many ways inwhich calorie intake can be increased and in whichcalorie expenditure can be increased. Calorie intakecan be reduced directly by conscious dietarymodifications or indirectly by bariatric surgery,pharmacology, and even psychological protocols.Conscious dietary modifications can themselves befurther subdivided into either (1) a reduction in foodvolume without changes in macronutrient ratios orfood choices or (2) a change in dietary patterns toalter either macronutrient ratios or food choices.Calorie expenditure can be increased either byphysical activity or by specific exercise protocols. Themajority of individuals in the general populationappear to instinctively identify diet as the primary wayto lose weight although many also include exercise asan adjunct. However, there are widely varyingopinions regarding the optimal ways to lose weightand experts have made recommendations regardingthe optimal macronutrient ratios, food choices,exercise protocols (i.e. aerobic steady state vs.anaerobic intervals vs. resistance training, etc.) andtarget rate of weight loss to achieve over a set periodof time. The extent to which these recommendationshave been supported by long-term trials, however, isunclear. In addition, the extent to which differenttypes of weight loss intervention lead to differentresults in males and females is also currentlyunknown.

OBJECTIVE: To assess whether a single-dose ofintranasal oxytocin (24IU) would affect appetite (asmeasured by visual analog scale (VAS) for appetite,caloric intake of self-selected food portions, and serumlevels of appetite-regulating hormones, insulin, andglucose) in fasting males.

POPULATION: 25 healthy males, aged 27.1 ± 1.5years.

INTERVENTION: The subjects received eitheroxytocin or a placebo, after which they were allowedto select breakfast from a menu and were givendouble portions.

What happened?

Caloric intakeThe researchers found that oxytocin did not affect thecaloric content of food ordered but it did significantlyreduce caloric intake by 122 ± 51kcal and fat intakeby 8.7 ± 3.8g. The reductions in protein (23.9 ± 2.2g)and carbohydrate (27.2 ± 9.4g) were not significant.

VAS appetiteThe researchers found that oxytocin did not affectsubjective appetite measures significantly.

Serum hormone and glucose levelsThe researchers found that oxytocin application didnot affect leptin, ghrelin, or PYY levels. Also, whileoxytocin application did not affect glucose levels, it didreduce average insulin levels.

What did the researchers conclude?The researchers concluded that a single dose ofintranasal oxytocin reduces total caloric intake by anaverage of 122 kcal at a subsequent meal.

LimitationsThe study was limited in that it involved a singleapplication and it is therefore unclear whetherrepeated applications would lead to the exact samebeneficial effects.


Creatine supplementation and lower limb strengthperformance: a systematic review and meta-analyses,by Lanhers, Pereira, Naughton, Trousselard, Lesage,and Dutheil, in Sports Medicine (2015)

BackgroundCreatine monohydrate is an athletic supplement usedby strength athletes and bodybuilders to improvemuscular strength and anaerobic power. It is thoughtto be effective by increasing muscular energy stores ofphosphocreatine but also appears to increase musclewater content. Indeed, some side effects of creatinesupplementation have been reported that may relateto increases in water retention, including musclecramping and gastrointestinal problems. However,despite previous concerns regarding renal damage andkidney dysfunction, the risks in these respects appearto be minimal. Additionally, some researchers havenoted that there is a theoretical mechanism by whichcreatine could cause toxicity by virtue of beingmetabolized into methyl-amine and then convertedinto formaldehyde. Indeed, some (but not all) studieshave reported increases in urinary formaldehyde inindividuals taking creatine for periods of time. Thedifferences in study findings could relate to thelengths of time studied or to the measurementmethods used. While creatine has been heavilyresearched in relation to the increases in muscularstrength and anaerobic power, and has good evidenceto support its use for these purposes, not all studieshave repor ted improvements in anaerob icperformance following creatine supplementation. Thisheterogeneity between studies has been exploredthrough various factors, including the type ofpopulation tested. For example, in a small number ofstudies, creatine has been found to be ineffective inelderly populations but the reasons for this areunclear. Also, it is possible that the timing of thecreatine supplement may be important, as somerecent studies have reported that consuming creatinepost-exercise may lead to superior results than atother times of day, including pre-exercise.

OBJECTIVE: To perform a systematic review andmeta-analyses to assess the effects of creatinesupplementation on strength tests involving the lowerbody muscles.

STUDY SELECTION: Studies included were onlyrandomized controlled trials in healthy males orfemales that compared the effects of a creatinesupplementation group with a control group on ananaerobic performance measure (lasting <3 minutes)using the lower body muscles.

What happened?

Study selectionThe researchers identified 60 randomized controlledtrials, which incorporated 646 individuals who tookcreatine supplementation and 651 control subjectswho did not. Most of the studies were double-blind,with only 5 being single-blind. The majority (74%) ofthe subjects were male and were either recreationallytrained (43%) or competitive athletes (37%).

Effects of creatine on lower body performanceThe researchers reported that the meta-analyses forchanges in strength following supplementation withcreatine compared with controls showed that therewas a significant effect for maximal weight lifted in thesquat (effect size = 0.390) and a non-significant effectfor total weight lifted in the leg press. The researchersnoted that the maximal weight lifted in the squat andthe total weight lifted during the leg press increasedby around 8% and 3%, respectively, following creatinesupplementation.

What did the researchers conclude?The researchers concluded that supplementation withcreatine is effective for acutely enhancing lower bodyanaerobic performance, specifically increasing bothsquat and leg press weight lifted.

LimitationsThe meta-analysis was limited in that it was unable todetermine whether changes in the weight lifted in theleg press or squat were affected by the amount ofcreatine taken, the duration over which it was taken,or the population who used it.


http://link.springer.com/article/10.1007/s40279-015-0337-4

Tendon cross-sectional area is not associated withmuscle volume, by Fukutani and Kurihara, in Journalof Applied Biomechanics (2015)

BackgroundTendons are connective tissue structures that connectmuscle to bone and permit the transference of tensileforce from the muscle to its associated joint. However,tendons are not simply inactive structures thattransmit muscle force. They have specific mechanicalcharacteristics that affect movement and function.Despite being non-contractile tissues, they perform arole in human movement by means of energyconservation and material deformation. Morespecifically, they have viscoelastic properties, whichmeans that they display both elastic and viscouscharacteristics, depending on the amount of loadapplied and on time for which this load is applied. Theelastic properties of tendons have been of particularinterest to researchers working in sport science. Forexample, it has been noted that the Achilles tendonfunctions as a biological spring during locomotion.During the early stance phase of gait, these tendonshave been found to store elastic energy andsubsequently release it in the late phase, therebyenhancing efficiency of movement. Increasing theability of tendons to store and release energy duringmovements would be highly valuable to athletes, as atendon that stored and released a greater amount ofenergy per foot stride would lead to greater propulsionfor the same amount of muscular force. Anatomically,tendons are comprised in a hierarchical format ofindividual collagen structures. Similar to the structureof muscles, tendons are comprised of single strands offibrils, made of collagen, which are bundled togethermaking increasingly larger structures: many fibrilsbecome fibers, many fibers become fascicles, whichultimately become the constituents of the wholetendon complex. Each bundle is tightly packed andsurrounded by a connective sheath, known as anendotendon. Tendons are mostly made from type Icollagen material, which is considered to beresponsible for the strength of the material againstdeformation, although tendons do also contain othertypes of collagen, most obviously type III collagen,which has been implicated in the healing process oftendon, but also seems to weaken the tendonstructure if too much is present. Additionally, theexact components of a tendon depend upon its preciselocation in the body. Tendons seem to respond tocertain mechanical loading protocols by increasingtheir size, measured as cross-sectional area. Forexample, some researchers have observed changes intendon cross-sectional area following long-termprograms of resistance training. However, the exactimplications of such changes are not entirely clear.

OBJECTIVE: To compare the relative muscle volumeand tendon cross-sectional area (using magneticresonance imaging (MRI) scans) of the triceps brachii,quadriceps femoris, and triceps surae between groupsof trained and untrained individuals in order to assesswhether there is a relationship between musclevolume and tendon cross-sectional area.

POPULATION: 16 trained males (either bodybuildersor rugby players), aged 21.3 ± 3.4 years (1RM benchpress = 131.1 ± 19.0kg and 1RM back squat = 162.2± 23.4kg) and 11 untrained males, aged 20.3 ± 2.1years.

What happened?

Differences between groupsThe researchers found that the muscles were allsignificantly larger (by muscle volume) in the trainedgroup than in the untrained group. However, theproximal and distal ends of the three tendons werenot significantly larger (by cross-sectional area) in thetrained group than in the untrained group, except thedistal end of the triceps surae tendon, which wasgreater in the trained group.

CorrelationsThe researchers found significant correlations betweenthe tendon cross-sectional area and the musclevolume for the proximal (r = 0.46) and distal (r =0.52) ends of the triceps surae but not for the othermuscles.

What did the researchers conclude?The researchers concluded that tendon cross-sectionalarea is not always associated with muscle volume.This may indicate that resistance training, or at leastnot all types of resistance training, increase tendoncross-sectional area in the same way as they increasemuscle volume.

LimitationsThe study was limited in that it was a cross-sectionalanalysis and it is therefore unclear what factorscontributed to the differences in relationships betweenthe muscles and tendons analyzed.



Oxandrolone augmentation of resistance training inolder women: a randomized trial, by Mavros, O'Neill,Connerty, Bean, Broe, Kiel, and Fiatarone, in Medicine& Science in Sports & Exercise (2015)

BackgroundAnabolic androgenic steroids (AAS) are currently inwidespread use by both competitive athletes,bodybuilders and recreational lifters to increasestrength and muscle mass. The research anddevelopment of synthetic steroid hormones began inthe 1930s and testosterone itself was isolated andsynthesized in 1935. This achievement was in factconsidered to be so important it actually earned theresearchers involved the Nobel prize in chemistry.However, while the use of AAS to improve theperformance of strength athletes is most stronglyassociated with the Soviet Olympic weightlifting teamsof the 1950s, there are some researchers who believethat East German athletes were using AAS prior tothat date. Nevertheless, it is thought that theintroduction of AAS to American athletes occurredfollowing contact between Soviet and US athletes andteam staff in the 1950s. Current knowledge about AASis sorely limited by their prohibited nature (whichmeans that it is very difficult to assess true prevalenceof usage) and also by ethical considerations, whichpreclude using long-term interventions to assess theireffects. Nevertheless, reviews of the availableliterature have concluded that in strength athletes,both short- and long-term AAS use significantlyincreases lean body mass but does not alter fat mass.The mechanisms by which AAS leads to increases inmuscle mass are thought to involve both hypertrophyand (contentiously) hyperplasia. Moreover, reviewershave concluded that the effects of AAS on lean bodymass are dose dependent, although it is unknownwhat parameters of AAS usage lead to the largestincreases. Additionally, researchers have noted thatthe upper body (upper back, neck, shoulders andupper arms) appear to be more susceptible to the useof AAS than other parts of the body and it is thoughtthat this occurs following a predominance of androgenreceptors in these areas. Since muscle mass is a keypredictor of strength, it is largely assumed thatstrength increases in line with AAS usage. Additionally,many athletes have reported that AAS use enhancesrecovery time from hard training but research has yetto confirm these anecdotal reports. Finally, althoughAAS use is associated variously with highly-desirableincreases in muscle mass, strength, and recoverycapacity, a number of studies have reported a range ofadverse effects, including the development of acnevulgaris, increased body hair, heightened aggressivebehavior, mood disturbances, heightened bloodpressure, and reduced levels of high-densitylipoproteins (HDL). The effects of AAS on humancardiac structure and function are unclear althoughanimal studies have revealed adverse effects.

OBJECTIVE: To perform a double-blind, randomized,placebo-controlled trial to assess whether the use ofAAS (oxandrolone) can improve muscular strength (asmeasured by 1RM machine leg press, chest press,triceps, knee extension and knee flexion), muscularpower (as measured by power outputs during the legpress and chest press), functional performance (asmeasured by static and dynamic balance, chair risetime, stair climb time, gait speed and the 6-minutewalk test), and body composition (as measured bydual energy X-ray absorptiometry [DEXA]) by morethan resistance training alone, in elderly females.

POPULATION: 29 sedentary and functionally limitedelderly females, aged 74.9 ± 6.8 years, randomlyallocated into either an AAS group or a placebo group.

INTERVENTION: All subjects performed a 12-weekprogram of resistance training, using 80% of 1RM for3 sets of 8 repetitions on the leg press, kneeextension, knee flexion, triceps pushdown, plantarflexion and chest press machines, 3 times per week.Subjects received either AAS (10mg per day ofoxandrolone) or a placebo with identical appearance.

What happened?

Body compositionThe researchers found that the AAS group displayedsignificantly greater increases in whole body leanmass, trunk lean mass, arm lean mass, and leg leanmass than the placebo group. The AAS group alsodisplayed significantly greater losses in whole body fatmass, body fat percentage, arm fat, and leg fat.

Muscular strength, power and functionThe researchers found that there were significantincreases in muscular strength, power, and functionalperformance in both AAS and placebo groups butthere was no significant difference between groups.

Adverse eventsThe researchers noted that there was only one reportof androgenic side effects reported in the AAS group.

What did the researchers conclude?The researchers concluded that the AAS oxandroloneenhances the increases in muscle mass and the lossesin fat mass that result from a standard 12-weekprogram of resistance training in elderly females.However, it does not appear to enhance the gains inmuscular strength, power or function.

LimitationsThe study was limited in that it is unclear whetherelderly males would have experienced better or worsebenefits from the AAS. The study was also limited inthat it is unclear how long it would take for the resultsto wear off after cessation of the treatment andwhether there were any adverse effects reported at alater follow-up.



Effects of resistance exercise and the use of anabolicandrogenic steroids on hemodynamic characteristicsand muscle damage markers in bodybuilders, byNadimi, Nasseri, and Nikookheslat, in The Journal ofSports Medicine and Physical Fitness (2015)

BackgroundAnabolic androgenic steroids (AAS) are currently inwidespread use by both competitive athletes,bodybuilders and recreational lifters to increasestrength and muscle mass. For a detailed introductionto AAS, please see the preceding study review.

OBJECTIVE: To compare the acute responses to asingle resistance training session between professionalbodybuilders who have used AAS and those who havenot used AAS, by taking measurements before,immediately after and at 24 hours after exercise.Responses to exercise that were measured included:heart rate, blood pressure, serum creatine kinase, andserum lactate dehydrogenase.

POPULATION: 16 top-level competitive bodybuilders,divided into 2 groups of 8 subjects: those using AASfor >5 years (AAS group) and those who have neverused AAS (non-AAS group). The AAS group used AASfor 25 ± 3.08 weeks per year with a mean weeklydosage of 581 ± 83mg.

INTERVENTION: All subjects performed a circuittraining session of 3 sets of 8 – 9 repetitions of 7exercises (leg press, bench press, leg extension, latpull, leg curl, shoulder press and biceps curl) with 80– 85% of 1RM.

What happened?

Baseline measurementsThe researchers found that heart rate (72.0 ± 5.3bpmvs. 59.50 ± 1.8bpm), systolic blood pressure (125.8 ±5.6mmHg vs. 111.6 ± 2.5mmHg), and diastolic bloodpressure (78.5 ± 3.7mmHg vs. 70.5 ± 1.6mmHg),serum creatine kinase levels (538 ± 273IU/L vs. 145± 42IU/L), and lactate dehydrogenase levels (301 ±92IU/L vs. 198 ± 49IU/L) were all higher in the AASgroup than in the non-AAS group at baseline beforeexercise.

Responses to exerciseThe researchers found that the circuit training sessionsignificantly increased heart rate in both groups butthe increase in the AAS group was significantly greaterthan the increase in the non-AAS group (125% vs.116%). Both groups significantly increased systolicblood pressure in response to exercise but there wasno difference between the AAS and non-AAS groups(7.6% vs. 8.3%). Diastolic blood pressure did notchange as a result of exercise in either group. Creatinekinase levels increased to a greater extent in the AASgroup than in the non-AAS group both immediatelypost-exercise (63% vs. 37%) and after 24 hours(206% vs. 115%).

What did the researchers conclude?The researchers concluded that AAS could lead toharmful effects through its impact on the cardio-respiratory system and markers of muscle damageboth at rest and post-exercise.

LimitationsThe study was limited in that it is unclear whether anyof the adaptations observed in this population wouldactually lead to any adverse effects.



Dietary Intake of Competitive Bodybuilders, bySpendlove, Mitchell, Gifford, Hackett, Slater, Cobley,and O’Connor, in Sports Medicine (2015)

BackgroundBodybuilding is generally regarded as one of the mostpopular strength sports, although it does not involve adirect test of strength or power. Bodybuilding involvesdisplaying a physique with high levels of muscularityand low levels of body fat, by means of a set posingroutine. Contestants typically prepare specifically forshows with long periods gaining muscular size,followed by long periods of dieting, in order to bringthe condition with the lowest possible levels of bodyfat. These preparatory periods involve carefullydesigned diets, resistance training routines, aerobicexercise, and supplementation. The study of suchroutines is of great interest but has rarely beenundertaken by researchers. Surveys and anecdotalreports indicate that most bodybuilders generally trainusing body-part splits, with 4 – 5 exercises per musclegroup, with moderate (7 – 12RM) loads, for highvolumes of around 3 – 6 sets per exercise, withmoderate inter-set rest periods (61 – 120 secondsbetween sets), and often make use of some advancedoverload techniques with some exercises. However,the pre-competition period sometimes involves atendency to increase the numbers of reps performed(to around 15 reps per set) and to decrease restperiods slightly (to around 30 – 60 seconds betweensets). Bodybuilders compete in two distinct types ofshow: natural and not natural. Natural bodybuildinginvolves preparing for the contest without the use ofperformance enhancing substances, which canincrease the amount of muscle mass gained and heldfor the competition, and which can enhance the loss offat and produce a more remarkable physique. Incontrast, competitions not marketed as being “naturalbodybuilding” are tacitly understood to permit the useof such performance enhancing substances, althoughmany of those used might technically be illegal incertain of the countries in which the competitions takeplace. The most commonly-used performanceenhancing substances in bodybuilding are thought tobe steroids of varying kinds, compounds to reduce anyundesirable side effects of the steroids (such as anti-estrogens), growth hormone, insulin, and fat-burners(such as clenbuterol or ephedrine).

OBJECTIVE: To carry out a systematic review ofstudies that have reported on the dietary intakepractices of competitive bodybuilders.

STUDY SELECTION: Any study was included where itreported quantitative data (energy and macronutrientratios) about the habitual dietary intake of competitivebodybuilders.

What happened?

Study selectionThe researchers found 18 studies reporting on 385subjects (323 male and 62 females). The researchersnoted that the mean quality rating score of the studieswas 7.4 ± 1.7 of a possible 15 points, indicating thatmost of the studies were of relatively low quality.

Characteristics of subjectsThe researchers noted that from all studies, the meanage of the males was 26.9 ± 4.7 years and the meanage of the females was 28.6 ± 4.2 years. The meanbody mass of the males was 83.7 ± 9.1kg and of thefemales was 54.2 ± 5.1kg. The mean body fatpercentage of the males was 12.1 ± 2.5% (range =4.7 – 17.0%) and of the females was 9.3 ± 2.1%(range = 8.4 – 11.1%).

Energy intake and macronutrient ratioThe researchers reported that energy intake rangedfrom 10 to 24 MJ per day for males and from 4 to 14MJ per day for females. Protein intake ranged from 1.9to 4.3g per kg of bodyweight per day for males,accounting for between 18 – 40% of total calories,and from 0.8 to 2.8g per kg of bodyweight per day forfemales, accounting for 10 – 39% of total calories.They found that carbohydrate intake ranged from 3.0gto 7.2g per kg of bodyweight per day for males,accounting for between 34 – 64% of total calories,and from 2.8g to 7.5g per kg of bodyweight per dayfor females, accounting for 48 to 78% of total calories.They found that absolute fat intake ranged from 19 to241g per day for males, accounting for between 8 –33% of total calories, and from 9 to 124g per day forfemales, accounting for 9 – 35% of total calories.

Supplement and drug useThe researchers reported that 6 of the 18 studiesreported on supplementation intake in males andnoted the use of protein powders or liquids, aminoacids, vitamins, minerals, and liver tablets. They foundthat 5 of the 18 studies reported the use of anabolicsteroids, diuretics and laxatives.

What did the researchers conclude?The researchers concluded that current research intothe dietary practices of bodybuilders is of relativelypoor quality.

LimitationsThe review was limited by the relative paucity ofresearch, which leads to difficulty in obtaining qualityinformation about this area.



A nutrition and conditioning intervention for naturalbodybuilding contest preparation – case study, byRobinson, Lambeth-Mansell, Gillibrand, Smith-Ryan,and Bannock, in Journal of the International Society ofSports Nutrition (2015)

BackgroundBodybuilding is generally regarded as one of the mostpopular strength sports, although it does not involve adirect test of strength or power. Bodybuilding involvesdisplaying a physique with high levels of muscularityand low levels of body fat, by means of a set posingroutine. For a detailed introduction to bodybuilding,see the preceding study review.

OBJECTIVE: To perform a case study to record theeffects of a bespoke nutrition and training program ina 21 year-old amateur bodybuilding competitor over a14-week preparation period on body composition (asmeasured by skin-folds and girths).

POPULATION: A single 21-year-old male amateurbodybuilder preparing to compete in his firstcompetition, in the Men’s Physique category.

INTERVENTION: The intervention comprised a dietand a training element. The diet element comprised aset-meal plan of two menus: one for training days andone for non-training days. The overall macronutrientsplit over the 14 weeks was 20 ± 3% carbohydrate,37 ± 4% fat, and 45 ± 8% protein but this overallsplit was modulated substantially over the course ofthe intervention, with carbohydrates starting at >200gper day and finishing at around 10 – 20g per day, inorder to maintain high levels of protein. The trainingelement involved 4 resistance-training sessions perweek, with each major muscle group being trained 2times per week. Each workout involved 6 – 8 exercisesfor 4 – 5 sets of 8 – 10 repetitions. The trainingelement also involved both high intensity intervaltraining (e.g. 10 sets of 10 – 15 second sprints) andlow-intensity steady-state (e.g. 40 minutes inclinetreadmill walking) exercise. The number of thesesessions performed increased as the date of thecompetition approached.

What happened?

Body composition changesThe researchers reported that the bodybuilder lost11.7kg of bodyweight over the 14-week period, oraround 1% of bodyweight per week. The loss in fatmass was 6.7kg (6.8% body fat) and the loss in leanmass was 5.0kg. This loss in lean mass represented43% of the total body mass lost and was greater thanin other case studies and observational research inbodybuilding preparation.

Explanations for lean mass lostThe researchers noted that the energy deficit in thiscase was greater than in many previous cases andobservational research that has been published, at882 ± 433 kcal per day. They also noted that previouscases and observational research have recorded theathletes consuming smaller proportions of fat andhigher proportions of carbohydrate. Either of thesemight explain the greater proportion of lean mass lostin this case but the study design does not allow for theexact reason to be determined.

What did the researchers conclude?The researchers concluded that their program waseffective in preparing the athlete for competition butproduced an unfavorable response in terms of leanmass lost.

LimitationsThe study was limited as it was a case study andtherefore it is unclear whether the results wereaffected by the individual response to the program.


http://link.springer.com/article/10.1186/s12970-015-0083-x

4. PHYSICAL THERAPY AND REHABILITATION


Acute effects of instrument assisted soft tissuemobilization vs. Foam rolling on knee and hip range ofmotion in soccer players, by Markovic, in Journal ofBodywork and Movement Therapies (2015)

BackgroundFascia is the soft tissue component of the connectivetissue system that both penetrates and surroundsmuscles, bones, organs, nerves, blood vessels andother structures and extends from head to toe, fromfront to back, and from surface to deep in anuninterrupted, three-dimensional web. It is widely-recognized as being part of a body-wide tensionalforce transmission system. Nevertheless, there hasbeen significant disagreement in respect of exactlywhat fascia comprises. This lack of agreement hascaused a great deal of confusion and differentanatomy textbooks and articles referring to fasciacontinue to do so on the basis of slightly differentdefinitions. Disagreements aside, researchers havedifferentiated between several layers of fascia: asuperficial fascia, a deep fascia and visceral fascia.The superficial fascia is a fibrous layer with amembranous appearance and abundant elastic fibersand occasional thin sub-layers of fat cells interspersedbetween layers of collagen fibers. The deep fasciaseems to differ in its make-up depending onanatomical location. In the trunk region, it is formedby a single layer of undulating collagen fibers mixedwith elastic fibers. Overall, fascia seems to helpmaintain structural integrity, provides support andprotection, acts as a shock absorber, has a role inhemodynamic and biochemical processes, provides thematrix permitting inter-cellular communication,functions as the body’s first line of defense againstpathogenic agents and infections, and creates anenvironment for tissue repair post-injury. The extentto which fascia is involved in these areas and itsrelative importance remains difficult to quantify, as thefield is rapidly evolving. However, based on thesefindings, it should not be surprising if studies reporteffects via fascia on areas as diverse as muscularforce transmission and arterial function. Myofascialrelease is a form of manual therapy that isincreasingly becoming used by physiotherapists andmanual therapists for treatment of many conditions,including musculoskeletal pain. Myofascial releaseinvolves the use of hands, knuckles, elbows or othertools to exert pressure on the muscles and fascia ofthe body. It is thought that by exerting pressure onthe muscles and fascia, areas of hardened muscleand/or fascia can be encouraged to relax. A number ofdifferent mechanisms have been proposed to explainhow this process might occur but there is currently nostrong consensus in favor of any single mechanism.Self-myofascial release (SMR) is simply that categoryof myofascial release techniques that are performedby the individual themselves rather than by a clinician.Consequently, SMR techniques most often involve atool with which the individual puts pressure upon theaffected area. The most commonly-used SMR tool isthe foam roller.

OBJECTIVE: To compare the effects of foam rollingwith a new form of tool-assisted myofascial release,called the Fascial Abrasion Technique (FAT), on acutechanges in hip and knee range of motion (ROM), asmeasured by both passive knee flexion and passivestraight leg raise tests before and after the treatmentas well as after 24 hours post-treatment, in athleticsubjects.

POPULATION: 20 male soccer players, randomlyallocated into either foam rolling or FAT groups.

INTERVENTION: The foam rolling group performed 2minutes of foam rolling over the quadriceps andhamstrings. The FAT group received a 2-minute FATtreatment to the same muscle groups, performed by aphysical therapist. Before the intervention, thesubjects performed a warm-up that included somestatic stretching of the quadriceps and hamstrings.

What happened?

Passive knee flexion ROMThe researcher reported that both groups significantlyimproved knee flexion ROM and they found nosignificant differences between groups directly post-treatment. Only the FAT group displayed a significantbenefit at 24 hours post-treatment.

Passive straight leg raise ROMThe researcher reported that both groups significantlyimproved hip flexion ROM and they found that the FATgroup improved significantly more than the foamrolling group directly post-treatment. Only the FATgroup displayed a significant benefit at 24 hours post-treatment.

What did the researchers conclude?The researchers concluded that the FAT treatment waseffective for increasing lower body flexibility acutelyand that the effects of the treatment lasted for >24hours.

LimitationsThe study was limited in that it did not make use of arandomized cross-over study design in which allsubjects were treated with both treatments. Thismeans that differences between the subjects couldhave accounted for the differences observed betweentreatments. The study was also limited in that thesubjects performed a warm-up that included somestatic stretching before both sets of tests.



Comparing the effects of self-myofascial release withstatic stretching on ankle range-of-motion inadolescent athletes, by Škarabot, Beardsley, andŠtirn, in International Journal of Sports PhysicalTherapy (2015)

BackgroundSelf-myofascial release (SMR) is simply that categoryof myofascial release techniques that are performedby the individual themselves rather than by a clinician.Consequently, SMR techniques most often involve atool with which the individual puts pressure upon theaffected area. The most commonly-used SMR tool isthe foam roller. For a detailed introduction to fascia,myofascial release, and self-myofascial release, seethe preceding study review.

OBJECTIVE: To compare the acute effects of staticstretching and foam rolling and a combination of bothfoam rolling and static stretching of the calf muscleson passive ankle dorsiflexion range of motion (ROM)using a weight-bearing lunge test in adolescentathletes with >6 months of resistance training andfoam rolling experience. Effects were measuredimmediately post-treatment as well as at 10, 15 and20 minutes post-treatment.

POPULATION: 11 resistance-trained, adolescentathletes with >6 months of both resistance-trainingand foam rolling experience.

INTERVENTION: All subjects performed a bout ofstatic stretching, a bout of foam rolling, and acombined bout of both foam rolling and staticstretching on different occasions. The static stretchingand foam rolling treatments each comprised 3 sets of30 seconds of the intervention with 10 seconds ofinter-set rest. The combined protocol comprised thefoam rolling treatment followed immediately by thestatic stretching treatment in sequence. After eachbout, flexibility was measured.

What happened?

Effects of foam rolling, static stretching and combinedThe researchers found that there was an overall effectfor a significant improvement in passive ankledorsiflexion ROM in all three treatments.

Time-course of effectsWhen testing to identify at what time points ROM wasincreased, significant increases were identified only forthe static stretching and combined conditions directlypost-treatment. Therefore, the effects were lost beforethe test at the 10-minute point.

Comparison between groupsThe researchers observed that there was a significantdifference between the combined condition and thefoam rolling condition.

What did the researchers conclude?The researchers concluded that foam rolling, staticstretching and a combined protocol of both foamrolling and static stretching all lead to acute increasesin flexibility. They concluded that a combined protocolof both foam rolling and static stretching appears tohave an additive effect in comparison with foam rollingalone. They concluded that all three protocols havetime courses that lasted <10 minutes.

LimitationsThe study was limited in that it is unclear why therewas a superior effect of the combined conditioncompared to the foam rolling condition. It may be thatthe increased volume of treatment was responsible orit may be that the two types of treatment are additive.



Incidence of running-related injuries per 1000 h ofrunning in different types of runners: a systematicreview and meta-analysis, by Videbæk, Bueno,Nielsen, and Rasmussen, in Sports Medicine (2015)

BackgroundAll physical activity involves a certain risk of injury,whether acute (traumatic) or chronic (overuse). Forelite amateur and professional athletes, these risksare accepted in return for the ultimate reward thatcomes from successful participation at the highestlevels. On the other hand, for non-elite amateurathletes and individuals who make use of participativesport for the purposes of exercise, injury risk (as wellas enjoyment) should be an important factor indeciding which type of sport to take part in. Some ofthe most popular amateur exercise pastimes are long-distance running, cycling and triathlon. However, theinjury risk associated with long-distance running ishigh. Injury risk in sports is typically assessed byreference to prevalence, incidence or rate. Injury ratesprovide the best metric for understanding injury risk,as they correct for the number of hours typically spentin performing the activity. Injury rates in long-distancerunning reported in the literature range from 2.5 –12.1 injuries per 1,000 hours training. Injury rates intriathlon are typically around half as high, from 1.4 –5.5 injuries per 1,000 hours training, which may implythat not focusing solely on one activity is less injuriousfrom an overuse perspective, or it may imply thatswimming and cycling are fundamentally lessdamaging than running. The injury incidence in longdistance running is also very high, with between 27 –79% of recreational and competitive runnerssustaining overuse injuries over the course of a singleyear. Injury during long-distance running is thought toarise from repetitive stress, which leads to cumulativemicro-trauma, causing overuse injury. Consequently, agreat deal of time and effort has been devoted tofinding different strategies that might reduce loadingand prevent overload. Proposals for helpful strategiesinclude: varying the type of loading by performing agreater amount of cross-training rather than running,switching from rear-foot to mid-foot or forefootstriking patterns in order to reduce the ground impactforces, varying shoe types in order to alter the loadingpatterns, and strengthening lower body muscles inorder to improve their ability to perform a shock-absorbing role during ground contact.

OBJECTIVE: To perform a systematic review andmeta-analyses of the literature in order to deduce theincidence of running-related injuries per 1,000 hoursof running in different categories of runner (novice,recreational and different competitive types).

STUDY SELECTION: All prospective cohort studiesand randomized controlled trials reporting theincidence of running-related injuries in novice,recreational, and ultra-marathon runners, as well as intrack and field athletes.

What happened?

Study selectionThe researchers identified 13 articles with data onrunning-related injuries per 1000 hours of running,comprising 8 prospective cohort studies and 5randomized controlled trials. Of these 13 articles, 5studies presented data in novice runners, 5 studiespresented data in recreational runners, 1 studypresented data in ultra-marathon runners, and 2studies presented data in track and field athletes.

Incidence of injury per 1,000 hoursThe incidences of injury per 1,000 hours across allstudies and groups of runner ranged from 2.5 to 33.0running-related injuries.

Meta-analysesThe researchers reported that the weighted estimateof running-related injury incidence in novice runnerswas 17.8 (16.7 – 19.1) injuries per 1,000 hours. Theyreported that reported that the weighted estimate ofrunning-related injury incidence in recreationalrunners was 7.7 (6.9 – 8.7) injuries per 1,000 hours.The incidence of injury was significantly higher innovice runners than in recreational runners.

What did the researchers conclude?The researchers concluded that novice runners face asignificantly greater risk of injury than recreationalrunners (17.8 vs. 7.7 injuries per 1,000 hours). Thissuggests that novice runners should engage cautionwhen setting out on a running program.

LimitationsThe systematic review and meta-analysis was limitedby the lack of literature presenting data on ultra-marathon and track and field athletes.



Novel methods of instruction in ACL injury preventionprograms, a systematic review, by Benjaminse,Welling, Otten, and Gokeler, in Physical Therapy inSport (2014)

BackgroundNon-contact anterior cruciate ligament (ACL) injury isa very common and quite serious injury that occursfrequently in popular team sports, particularly thosewhich involve lateral pivoting, jump landing or quickdecelerations during sprint running. Previous researchhas identified that ACL injuries occur under twopredominant loading patterns: knee valgus collapse oranterior tibial shear. While there are advocates andadversaries of both mechanisms, studies have shownthat female athletes tend to display greater kneevalgus than males and greater ACL injury incidence.Researchers have also found that the tendency todisplay greater knee valgus is a good predictor of ACLinjury risk. In general, the term “valgus” refers to theoutward angling of the distal segment of a bone.Where a joint or a neighboring joint has more thanone degree of freedom, this outward angling caninvolve movements in transverse, sagittal or frontalplanes. Indeed, research indicates that knee valgus(also called valgus collapse or medial kneedisplacement) actually arises as a result of hip joint orfoot joint actions. Knee valgus in stance is seen inconjunction with a combination of hip joint adductionand hip joint internal rotation and occurs mostfrequently in positions of hip joint flexion. Additionally,foot pronation is commonly observed where kneevalgus occurs. The joint actions at hip and foot appearto lead to a medial displacement of the knee, which isaccompanied by knee joint abduction and knee jointexternal rotation. Various explanations have beenproposed as causes of knee valgus. One popularproposal is that individuals have inadequate hipexternal rotator and hip abductor strength and/orshort, tight or overactive hip adductors and/or hipinternal rotations, leading to a tendency for the hips tomove into hip adduction and hip internal rotation.Another very popular proposal is that ankledorsiflexion mobility is poor or that the lower legmuscles (soleus, gastrocnemius, and anterior tibialis)are short, tight or overactive, which prevents the tibiaand knee from moving forwards and causes the foot tocompensate by pronating. This inward foot movementleads to mirrored movement at the hip (hip internalrotation and hip adduction) and therefore knee valgus.Two less popular proposals are that a lack of eithervastus medialis obliquus strength or a lack of medialhamstrings strength leads to poor knee stabilizationand consequently allows the knee to track inward.Changes of direction during running (cutting) arecommon in many popular team sports and the abilityto perform them quickly is a key attribute ofsuccessful athletes. However, cutting maneuvers arealso associated with knee valgus and consequently anincreased risk of non-contact ACL injury.

OBJECTIVE: To perform a systematic review of theliterature in order to compare the effects of internaland external cues on jump landing technique.

STUDY SELECTION: Studies were included thatincorporated healthy adult subjects, in which theeffects of both internal and external cues wereexamined on jump and landing performance or jointangle movements.

What happened?

Study selectionThe researchers identified 9 articles with resultscomparing the effects of internal and external cues oneither performance or joint angle movements duringjumps. The subjects per study ranged from 8 to 120individuals. The maximal vertical jump was explored in4 studies, the standing long jump was explored in 4studies, the countermovement jump was explored in 1study and the two-leg drop jump was explored in 2studies.

Effect of internal and external cues on performanceThe reviewers noted that 4 studies reported significantincreases in vertical jump height and 3 studiesreported increases in standing long jump distancefollowing the use of external cues compared to the useof internal cues.

Effect of internal and external cues on joint anglesThe reviewers found that 1 study reported significantlygreater knee flexion (i.e. better landing technique)during the standing long jump and a counter-movement jump but not during a drop jump whenusing external cues rather than internal cues.

What did the researchers conclude?The reviewers concluded that the use of external cuesmay be beneficial for use in ACL injury preventionprograms on the basis that they improve performanceand may also improve jump landing technique.

LimitationsThe review was limited by the severe lack of studiesassessing the effect of different types of cue onlanding technique.



Acute hamstring injury in football players: associationbetween anatomical location and extent of injury—alarge single-center MRI report, by Crema, Guermazi,Tol, Niu, Hamilton, and Roemer, in Journal of Scienceand Medicine in Sport (2015)

BackgroundHamstring strains are a common injury in manypopular team sports. They account for 12 – 16% of allinjuries in athletes across a range of popular teamsports, including rugby, soccer, American Football, andAustralian Rules Football. The re-injury rate forhamstring strains ranges from 16 – 34%, dependingupon the sport. Running activities account for mosthamstring strains, with 57 – 68% of strains occurringduring running. The traditional model for hamstringstrain injury is that there are various factors that couldcause an injury to occur, including: flexibility, strength,fatigue, core stability, muscle architecture, anddamage resulting from previous injury. A modern,more sophisticated approach has suggested that whilethese factors could individually lead to an injury, it ismore likely that they interact with each other in orderto create multi-factorial scenarios that raise injuryrisk. Some researchers have suggested that there areat least two different types of hamstring strain injury:those caused by stretching activities and those causedby high-speed running movements. The hamstringstrain injury caused by high-speed running is thoughtto occur most normally in the long head of bicepsfemoris, typically involves the proximal muscle-tendonjunction, displays a greater reduction in strengthfollowing injury than those following stretchingmovements, and leads to a relatively long recoverytime to reach pre-injury levels of performance (e.g.around 50 weeks). The biceps femoris (long head) isgenerally thought to be the most commonly-injuredhamstring muscle, although some researchers havesuggested that this perception might be incorrectbecause of inherent errors in common diagnosticapproaches. Biomechanically, however, there are goodreasons for assuming that the biceps femoris might bemost at risk. Firstly, this muscle increases in length bymore than the other hamstring muscles duringsprinting. Secondly, the moment arm lengths of thebiceps femoris in the sagittal plane increase in the lateswing position compared to the anatomical position.Previous research has identified that hamstring strainsoccur most frequently either in the late swing or earlystance phases of gait. Late swing involves the greateststrain in the muscle, while early stance involves thelargest joint moments. There is good evidence tosuggest that hamstring strain injuries can be reducedby eccentric hamstring training but not by flexibilitytraining alone. This has encouraged many strengthcoaches to incorporate the Nordic hamstring curl intohamstring strain prevention programs. However, thereis only limited evidence to suggest that hamstringweakness predicts strain injury risk. Moreover, whyeccentric training might be so effective is notcompletely clear.

OBJECTIVE: To identify the exact anatomic locationof acute hamstring injuries in soccer players and toexplore whether there is a relationship between theanatomical location and the severity of the injury, asseen using magnetic resonance imaging (MRI) scans.

POPULATION: 275 consecutive male soccer players,aged 25 ± 5.2 years, with acute hamstring straininjuries that displayed positive findings on an MRIscan.

What happened?

Injury number and typeIn the 275 soccer players, the researchers identified atotal of 393 lesions, of which 348 had measurableedema (87%), and 109 (28%) had measurable tears(with edema as well).

Anatomical locations most commonly injuredThe researchers reported that (in line with previousresearch) the long head of biceps femoris was themost commonly injured hamstring muscle, accountingfor 222 of the 393 lesions (57%). For the bicepsfemoris, injuries in proximal and distal regions weresimilar in number (125 vs. 113 injuries) but for themedial hamstrings, the proximal regions were injuredmore often than the distal regions. For specificlocations within the long head of the biceps femoris,the researchers noted that the proximal myotendinousjunction location was the most commonly affected(105 injuries).

What did the researchers conclude?The researchers concluded that the biceps femoris(long head) is the most commonly injured hamstringmuscle. They concluded that although injuries to thebiceps femoris (long head) are split evenly betweenproximal and distal locations, the specific locationmost commonly injured is the proximal myotendinousjunction. For the medial hamstrings, the proximalregions were injured more often than the distalregions.

LimitationsThe study was limited in that it was retrospective andonly included those subjects who had meaningfulfindings on MRI scans.



Rationale, secondary outcome scores and 1-yearfollow-up of a randomised trial of platelet-rich plasmainjections in acute hamstring muscle injury – theDutch hamstring injection therapy study, by Reurink,Goudswaard, Moen, Weir, Verhaar, Bierma-Zeinstra,and Tol, in British Journal of Sports Medicine (2015)

BackgroundHamstring strains are a common injury in manypopular team sports. They account for 12 – 16% of allinjuries in athletes across a range of popular teamsports, including rugby, soccer, American Football, andAustralian Rules Football. For a detailed introduction tohamstring strains, see the preceding study review.

OBJECTIVE: To assess whether platelet-rich plasmainjections can affect the speed of return to play, therisk of re-injury during 1-year follow-up, changes inflexibility (as measured by the active knee extensionand passive straight leg raise tests), and changes instrength (as measured by isometric knee flexion forcewith a hand-held dynamometer), after an acutehamstring strain injury.

POPULATION: 80 competitive or recreational athleteswith acute hamstring strain injury, as defined byhaving lesions on magnetic resonance imaging (MRI)scans.

INTERVENTION: The subjects in the treatment groupreceived one injection of platelet-rich plasma within 5days of injury and a second injection 5 – 7 days later.The subjects in the control group received a placebo.

What happened?

Return to play and risk of re-injuryThe researchers found no significant differencebetween the two groups in relation to the time takenbefore return to play. They also found no significantdifference between the two groups in relation to therisk of re-injury. In the platelet-rich plasma group,27% of the individuals experienced a repeat injury inthe follow-up period. In the placebo group, 30% of theindividuals experienced a repeat injury.

Flexibility and strengthThe researchers found no significant differencebetween the two groups in relation to hamstringflexibility (as measured by both active knee extensionand passive straight leg raise tests). They also foundno significant difference between the two groups inrelation to changes in isometric knee flexion force.

What did the researchers conclude?The researchers concluded injections with platelet-richplasma do not reduce the time taken to return to play.They also concluded that they do not affect 1-year re-injury rates. Additionally, they found that they have noeffect on either hamstring flexibility or strength at thepoint of return to sport. They concluded that injectionswith platelet-rich plasma are not an effectivetreatment for hamstring strain injury.

LimitationsThe study was limited in that it was only performed inhamstring strains and different results might beobserved in other acute muscle injuries.


http://bjsm.bmj.com/content/early/2015/05/03/bjsports-2014-094250.abstract

The biomechanics of running in athletes with previoushamstring injury – a case-control study, by Daly,McCarthy Persson, Twycross‐Lewis, Woledge, andMorrissey, in Scandinavian Journal of Medicine &Science in Sports (2015)

BackgroundHamstring strain injury is one of the most commoninjuries among team sports athletes, including rugby,Australian Rules football, and soccer. Such injuries canbe very debilitating and may in some cases lead to acurtailment of athletic careers. The precise mechanismby which hamstring strains occur is disputed. Someresearchers propose that the injury occurs during thelate swing phase while others maintain that it is morelikely to happen upon ground contact. It was initiallyassumed that hamstring strains occurred during earlystance, as this was the point at which knee flexion andhip extension moments appeared to be greatest. Thisproposal was therefore predicated upon theassumption that the magnitude of mechanical tensionis the key factor for the likelihood of muscle strains.Later researchers rejected this idea, as the likelihoodof muscle strains was found to be more closely relatedto the extent of the mechanical strain, rather than themagnitude of the mechanical tension. Thus, when itwas found that the hamstrings achieved maximallengthening during the late swing phase, it wasproposed that this part of the gait cycle was morecritical for understanding hamstring strains. However,some of the studies used to establish theseconclusions were performed in accelerating sprintrunning and therefore it is unclear whether the sameresults would be observed in maximal speed sprintrunning. Also, some of the studies tested athletesduring treadmill running instead of overgroundrunning and therefore it is unclear whether the sameresults are observed during overground running.

OBJECTIVE: To compare the muscle activity (by usingelectromyography [EMG]) and joint angle movements(by using an infrared motion analysis system) of elitemale Gaelic games athletes with and without previoushamstring strain injury.

POPULATION: 17 elite male Gaelic games athletes (9with previous hamstring strains and 8 matchedcontrols).

What happened?

Muscle activityThe researchers found that those individuals who hadbeen previously injured displayed significantly lowerbiceps femoris muscle activity relative to gluteusmaximus muscle activity, erector spinae muscleactivity, external oblique muscle activity, and rectusfemoris muscle activity in the late swing phase.

Joint angle movementsThe researchers found that those individuals who hadbeen previously injured displayed significantlyasymmetrical movement patterns in the sagittal planewhereas the uninjured group did not display anymeaningful asymmetry. They noted that in the lateswing phase, the previously injured group displayedan increase in anterior pelvic tilt and hip flexion on theinjured side but reduced anterior pelvic tilt and hipflexion on the uninjured side. The asymmetry couldlead to greater lengthening (strain) of the injuredhamstring, which could predispose it to greater futureinjury risk.

What did the researchers conclude?The researchers concluded that previous hamstringinjury is associated with reduced biceps femorismuscle activity and joint angle movement changesduring the late swing phase that could lead to greaterlengthening of the previously injured hamstringmuscle during running, and thereby increased futureinjury risk.

LimitationsThe study was limited in that it was a retrospectiveinjury study and it is unclear whether the differencesin joint angle movements were present before theinitial injury occurred or whether they arose as aresult of the injury.


http://onlinelibrary.wiley.com/doi/10.1111/sms.12464/full

Evaluation of a treatment algorithm for patients withpatellofemoral pain syndrome: a pilot study, bySelhorst, Rice, Degenhart, Jackowski, and Tatman, inInternational Journal of Sports Physical Therapy(2015)

BackgroundPatellofemoral pain syndrome (PFPS) occurs veryfrequently in young adult females. It is also the mostcommon injury affecting recreational endurancerunners. However, despite being so common, its exactcause remains unclear and diagnosis of PFPS is usuallymade once other, more easily diagnosed conditionshave been ruled out. Nevertheless, many researchersbelieve that lower-body biomechanics are a key factorin the development of PFPS. Previous studies havefound that females with the disorder display severalspecific features, including: greater lateral patellardisplacement and greater internal femoral rotation atseveral knee flexion angles. This is important, as alarger Q-angle has also been proposed as ananthropometric feature that predisposes individuals toPFPS. The existence of the Q-angle means that thereis naturally a lateral pull on the patella. Thus, if certainbiomechanical features increase the size of this lateralpull, this could increase the risk of greater lateraltracking of the patella, which may in turn cause kneepain. The single-leg squat has often been used toexplore the biomechanics of knee movement in thecontext of PFPS. Studies have found that individualssuffering from PFPS display a greater frontal planeprojection angle during the single-leg squat thanasymptomatic individuals. Frontal plane projectionangle is a simple, 2D method of measuring kneealignment. Angle of hip adduction is closely correlatedwith frontal plane projection angle and prospectivecohort studies have reported that this angle ispredictive of the development of PFPS in femaleathletes without PFPS at baseline. Additionally,reviews have found that lower hip external rotator,abductor, and hip extensor strength are frequentlyreported in individuals with PFPS compared toindividuals without PFPS. While such studies do notestablish the extent to which disuse atrophy may playa role, other prospective studies have made similarfindings. The connection between the various riskfactors may be found in the varied role of the gluteusmaximus, which acts variously as a hip extensor, hipexternal rotator and hip abductor. Thus, in controllinginternal rotation, and by implication knee valgusduring single-leg movements, the strength of thegluteus maximus could be important for PFPS.

OBJECTIVE: To perform a pilot study assessing thefeasibility of a program of care for patients with PFPS,in which the treatment is performed in sequentialphases: Fear-Avoidance, Flexibility, Functional Mal-alignment, and Strengthening. Patients were onlyrequired to complete a phase if they scored below thethreshold on the outcome measure test at the outset.The overall assessment of PFPS was carried out withthe Numeric Pain Rating Scale (NPRS), the AnteriorKnee Pain Scale (AKPS), and the Global Rating ofChange Scale (GROC). The AKPS scale is the currentgold standard for measuring function in patients withPFPS.

POPULATION: 30 consecutive patients with PFPSwho were referred to physical therapy.

INTERVENTION: All patients were provided withphysical therapy treatments 2 times per week for 6weeks as well as a home exercise program to beperformed daily. The Fear-Avoidance phase involved:fear avoidance education and graded exercise using acognitive behavior approach. The Flexibility phaseinvolved stretching tight primary and secondarymuscles along with some quadriceps and hip musclestrengthening exercises. The Functional Mal-alignmentphase involved regaining neuromuscular control ofcore and lower extremity during dynamic movement.The Strengthening phase involved exercise tostrengthen the lower body with a focus on quadriceps,hip abductors and hip external rotators.

What happened? The researchers found that at the 6-week follow-up,there was a significant improvement in the AKPS, witha mean change of 18.00 ± 6.27 points, no significantchange in NPRS, with a mean improvement of -1.84 ±1.04 points, and a significant improvement in theGROC, with a mean change of 5.30 ± 1.42 points.

What did the researchers conclude?The researchers concluded their sequential treatmentapproach involving Fear-Avoidance, Flexibility,Functional Mal-alignment, and Strengthening phaseswas effective at improving PFPS function scores.

LimitationsThe study was limited in that it was a pilot trial anddid not involve a control group receiving normaltreatment. It is therefore uncertain whether thisprogram is superior to current practice.



Strengthening the hip muscles in individuals withpatellofemoral pain: what can be learned from theliterature?. By Dorey and Williams, in PhysicalTherapy Reviews (2015)

BackgroundPatellofemoral pain syndrome (PFPS) occurs veryfrequently in young adult females. It is also the mostcommon injury affecting recreational endurancerunners. For a detailed introduction to PFPS, see thepreceding study review.

OBJECTIVE: To perform a systematic review of theliterature examining the effects of different hipstrengthening protocols on pain and hip strength inindividuals with PFPS.

STUDY SELECTION: Studies of any design wereincluded, so long as they explored programs ofstrengthening for the hip abductors and externalrotators in adults with PFPS, where the outcomemeasures included hip muscle strength and pain usinga visual analogue scale (VAS).

What happened?

Study selectionThe researchers found 5 articles that met the inclusioncriteria, which included 3 randomized controlled trials,1 case series, and 1 case report.

Effects on painThe researchers observed that all of the investigationsreported significant improvements in pain scores, byreference to a VAS, where such statistical analysis wasperformed. However, they did not identify anysignificant correlation between the change in painscores and the change in hip external rotator or hipabductor strength.

Effects of hip strengthThe researchers observed that all but one of theinvestigations reported significant improvements in hipstrength, where statistical analysis was performed.

What did the researchers conclude?The researchers concluded that programs of hipstrengthening lead to significant improvements in hipstrength and reductions in pain in individuals withPFPS.

LimitationsThe review was very limited by the limited literatureincluded within it. Different results might be obtainedby a wider set of inclusion criteria.


http://www.maneyonline.com/doi/abs/10.1179/1743288X15Y.0000000008

Prevalence and pattern of radiographic intervertebraldisc degeneration in Vietnamese – a population-basedstudy, by Ho-Pham, Lai, Mai, Doan, Pham, andNguyen, in Calcified Tissue International (2015)

BackgroundThe human spine is a highly complex set of bones andjoints. It comprises 24 articulating vertebrae, whichcan be allocated into the lumbar (5), thoracic (12) andcervical (7) sections, and a further 9 non-articulatingvertebrae that form the sacrum and coccyx. Eacharticulating vertebra is separated from the next byintervertebral discs. Each intervertebral disc forms afibrocartilaginous joint that permits a slight movementof the vertebrae and functions as a shock absorber.The intervertebral disc comprises two main parts: anouter fibrous ring (the anulus fibrosus) comprisingseveral layers of fibrocartilage that help distributepressure evenly across the surface of the disc and aninner center (the nucleus pulposus) that containsloose fibers suspended in a shock-absorbing gel. Thesize of each articulating vertebra differs depending onits location, the loading that it has becomeaccustomed to experiencing, posture and the presenceof any pathology. Each vertebra comprises twoseparate parts: the vertebral body and the vertebralarch, which is posteriorly-facing. The spine serves toprovide structure to the body and also protects thespinal cord, which runs through between the vertebralbody and the vertebral arch. The spine has fourdistinct curves of alternating directions in the sagittalplane. Each curve is associated with each separatesection. The cervical and lumbar sections both haveconvex anterior-facing curves while the thoracic andsacral sections both have concave anterior-facingcurves. The articulating elements of the spine and itscurvatures allow for a complex variety of movementsand ranges of motion, including extension and flexion,lateral flexion (right and left), and axial rotation(clockwise and anti-clockwise). There are a number ofdifferent measurement methods for spinal range ofmotion (ROM) for the varying different sections andalso at individual vertebrae and norms have beenestablished in populations of various ages, with manyof the measures reducing in magnitude with increasingage.

OBJECTIVE: To assess the prevalence of radiographicintervertebral disc degeneration in the Vietnamesepopulation, by examination of radiographs of thecervical spine, thoracic spine and lumbar spine toidentify the presence of disc space narrowing and/orosteophytosis using the Kellgren–Lawrence gradingsystem

POPULATION: A random sample of 170 men and 488women aged >40 years, living in Ho Chi Minh City(Vietnam).

What happened?

Prevalence of intervertebral disc degenerationThe researchers reported that the overall prevalenceof radiographic intervertebral disc degeneration was62.4% in males and 54.7% in females.

Regions most commonly affectedThe researchers reported that the most frequentlyaffected region was the lumbar spine with prevalenceof radiographic intervertebral disc degeneration being50.6% in males and 43.2% in females.

Effect of ageThe researchers reported that the prevalence ofintervertebral disc degeneration increased markedlywith increasing age, being just 18.8% in individualsaged 40 – 49 years but 83.4% in those aged >60years.

Self-reported neck and back painThe researchers observed that the prevalence of self-reported neck pain and/or stiffness was 20% in malesand 33% in females. The prevalence of self-reportedlow back pain and/or stiffness was 30% in males and49% in females.

Correlation with painThe researchers found no significant associationbetween self-reported neck pain and/or stiffness andcervical spine intervertebral disc degeneration.However, they did observe that individuals with lowback pain were 1.59 times more likely to displayevidence of some lumbar spine intervertebral discdegeneration.

What did the researchers conclude?The researchers concluded that a large proportion ofindividuals in Vietnam display intervertebral discdegeneration. They concluded that males have ahigher prevalence of intervertebral disc degenerationthan females. They concluded that there was noassociation between self-reported neck pain andcervical spine intervertebral disc degeneration butthere was a small association between self-reportedlow back pain and lumbar spine intervertebral discdegeneration.

LimitationsThe study was limited in that it did not report lifestylefactors that may have been predictors of either pain orintervertebral disc degeneration.



Breathing techniques affect female but not male hipflexion range of motion, by Hamilton, Beck, Kaulbach,Kenny, Basset, DiSanto, and Behm, in Journal ofStrength & Conditioning Research (2015)

BackgroundFlexibility is important for both athletes and for thegeneral population. Flexibility is defined as the abilityto move through a specific joint range of motion(ROM). Stretching is commonly used to helpindividuals achieve greater joint ROM. Researchershave generally proposed two types of mechanism bywhich increases in flexibility can be achieved. Onetype of mechanism involves a mechanical change inthe behavior of the muscle tissue while the other typeinvolves a change in sensation. However, there are atleast four theories that detail ways in which some kindof mechanical change could occur: viscoelasticdeformation, plastic deformation, increased number ofsarcomeres in series, and neuromuscular relaxation.However, the evidence to support these has beenfound to be weak. In contrast, many studies havereported that the only variable that changes followingstretching programs in tandem with flexibility is thesensation of pain (i.e. maximum pain and onset ofpain) during the stretch. This supports the sensationtheory of stretching. Researchers advocating thistheory have formulated the hypothesis that stretchingincreases flexibility by reducing the sensation ofincreasing muscle length. Nevertheless, irrespective ofhow stretching changes joint flexibility, it is apparentthat it can achieve increases in joint ROM that last > 1day. There are two main types of stretching that areexplored in the literature: static and dynamicstretching. Static stretching involves moving a joint tothe end of its ROM and holding this stretched positionfor a set period of time. On the other hand, dynamicstretching involves controlled movements through theactive ROM for a joint. While both static and dynamicstretching have been found to improve joint ROM,static stretching performed for >45 seconds appearsto lead to meaningful acute reductions in performancetasks, such as vertical jumping, whereas dynamicstretching performed for long durations appears tolead to either no improvement or small improvementsin the same type of actions. It is interesting to notethat reviews of the chronic effects of static stretchinghave actually found beneficial effects on both athleticperformance and strength measures. The literature iscurrently conflicting regarding whether regular staticor dynamic stretching is effective for reducing the riskof sports injury, whether the stretching is performedimmediately prior to exercise or at another time.Additionally, the exact duration of stretches, the totalvolume and frequency of stretching per week, and therest periods between stretches that are optimal for themost efficient increases in joint ROM are currentlyunknown.

OBJECTIVE: Two studies were performed to examinethe effects of breathing techniques on passive hipflexion ROM and trunk muscle activity (as measuredby electromyography [EMG]) of the rectus abdominis,external obliques, lower abdominals, and the lowererector spinae.

POPULATION: For the first study: 30 recreationallyactive subjects (15 males and 15 females, aged 22.2± 1.2 years). For the second study: 18 recreationallyactive subjects (9 males and 9 females, aged 23.1 ±1.5 years).

INTERVENTION: The first study comprised a test ofpassive straight-leg raise ROM under 7 breathingconditions (pre-stretch inhale, pre-stretch exhale,inhale during stretch, exhale during stretch, neutral,pre-stretch hyperventilation and pre-stretch hypo-ventilation). The second study comprised a test ofmuscle activity while performing the same 7 breathingconditions either before or during a passive straight-leg raise stretch.

What happened?

Straight-leg raise ROMThe researchers found that the males displayed noeffect of breathing condition on straight-leg raise ROM.However, they noted that in females, the controlcondition displayed a smaller passive straight-leg raiseROM than the pre-stretch inhale condition (by 7.7%),the inhale during stretch condition (by 10.9%), andthe hypoventilation condition (by 11.2%).

Muscle activityThe researchers observed greater muscle activity inthe pre-stretch exhale condition than in the inhaleduring stretch condition (by 43.1%) and in the hypo-ventilation condition (by 51.2%).

What did the researchers conclude?The researchers concluded that breathing techniquecan affect both passive flexibility and muscle activity.It is unclear how this occurs.

LimitationsThe study was limited in that it was unable todetermine why there were changes in flexibility andtrunk muscle activity as a result of the differentbreathing conditions. Moreover, it is unclear why therewere differences between males and females.


http://pdfs.journals.lww.com/nsca-jscr/9000/00000/Breathing_techniques_affect_female_but_not_male.96910.pdf

Viscoelastic stress relaxation in the hamstrings beforeand after a 10-week stretching program, by Peixoto,Andrade, Menzel, Araújo, Pertence, and Chagas, inMuscle & Nerve (2015)

BackgroundFlexibility is important for both athletes and for thegeneral population. Flexibility is defined as the abilityto move through a specific joint range of motion(ROM). Stretching is commonly used to helpindividuals achieve greater joint ROM. For a detailedintroduction to stretching, see the preceding studyreview.

OBJECTIVE: To explore the effects of a 10-weekprogram of static stretching for the hamstrings onchanges in hamstrings flexibility and in viscoelasticstress relaxation response over multiple passivestretches (as measured by the relative stressrelaxation). The viscoelastic stress relaxation responseis the decline in passive tension over time as themuscle is held at a constant length. The relative stressrelaxation calculation is: peak torque minus the torqueat 30 seconds, multiplied by 100%.

POPULATION: 13 untrained males, aged 20.8 ± 2.0years.

INTERVENTION: All subjects undertook a staticstretching program comprising 6 stretches of 30seconds per stretch, 4 times per week for 10 weeks.The stretch was performed using a dynamometer andwas set at 70% of maximum passive resistive kneeextension torque for the first 2 weeks and adjustedupwards thereafter every 2 weeks.

What happened?

FlexibilityThe researchers found that flexibility increased from75.0 ± 10.8 degrees to 114.8 ± 16.3 degrees as aresult of the hamstring stretching program.

Relative stress relaxationThe researchers found that relative stress relaxationwas significantly decreased for the first, second andthird repetitions after the stretching protocol.However, there was no effect on repetitions 4 – 6.

What did the researchers conclude?The researchers concluded that regularly participatingin a stretching program leads to a significantly loweracute relative stress relaxation response to stretching.

LimitationsThe study was limited in that it is not possible toascertain the mechanism by which the change inrelative stress relaxation occurred.


http://onlinelibrary.wiley.com/doi/10.1002/mus.24593/full

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