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[Applied Sciences Biodynamics]
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Medicine amp Science in Sports amp Exercise
Issue Volume 28(2) February 1996 pp 218-224
Copyright copy1996The American College of Sports Medicine
Publication Type [Applied Sciences Biodynamics]
ISSN 0195-9131
Accession 00005768-199602000-00010
Keywords WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
High- and low-bar squatting techniques during weight-training
WRETENBERG PER FENG YI ARBORELIUS ULF P
Author InformationKinesiology Research Group Department of Neuroscience Karolinska Institute S-171 77 Stockholm SWEDEN
Submitted for publication December 1993
Accepted for publication October 1994
Address for correspondence Per Wretenberg Kinesiology Research Group Department of Neuroscience Karolinska Institute S-171 77
Stockholm Sweden
ABSTRACT
Eight Swedish national class weightlifters performed ldquohigh-barrdquo squats and six national
class powerlifters performed ldquolow-barrdquo squats with a barbell weight of 65 of their 1 RM
and to parallel- and a deep-squatting depth Ground reaction forces were measured with a
Kistler piezo-electric force platform and motion was analyzed from a video record of the
squats A computer program based on free-body mechanics was designed to calculate
moments of force about the hip and knee joints EMG from vastus lateralis rectus femoris
and biceps femoris was recorded and normalized The peak moments of force were flexing
both for the hip and the knee The mean peak moments of force at the hip were for the
weightlifters 230 Nm (deep) and 216 Nm (parallel) and for the powerlifters 324 Nm (deep)
and 309 Nm(parallel) At the knee the mean peak moments for the weightlifters were 191
Nm (deep) and 131 Nm (parallel) and for the powerlifters 139 Nm (deep) and 92 Nm
(parallel) The weightlifters had the load more equally distributed between hip and knee
whereas the powerlifters put relatively more load on the hip joint The thigh muscular activity
was slightly higher for the powerlifters
The squatting exercise performing a knee bend while carrying a weight on the shoulders
is an often used and important method for hip knee and back muscle training (3182223)
Many athletes in different disciplines use this type of exercise as the basic exercise to
strengthen the leg muscles and the method is considered supreme for this purpose by many
coaches (429) Weightlifters and powerlifters use squatting as one of the most important
parts of their training programs and for the powerlifters this kind of squatting is directly
included during their competition performance (131415) In the weightlifting competition
the back squat is not directly included rather the front-squat with the barbell on the chest
still the back-squat training is important also for the weightlifters
The squatting exercise can be performed in different ways The weights on the shoulders
and numbers of repetitions can vary depending on the purpose Squatting depth is another
important factor and the parallel and deep squat dominates During the parallel squat the
knees are flexed until the posterior borders of the hamstrings muscles are parallel to the
floor whereas during the deep squat the knees are maximally flexed In a previous study
(32) we showed that the quadriceps muscle activity is the same for these two different types
of squats but that the load on the knee joints is larger for the deep squat
of squats but that the load on the knee joints is larger for the deep squat
There are two main techniques for the squatting exercise with the bar on the back the
ldquohigh-barrdquo squat and the ldquolow-barrdquo squat (29) The names of the techniques are related to
the placement of the bar on the back The bar is either centered across the shoulders just
below the spinous process of the C7 vertebraldquohigh-barrdquo or further down on the back across
the spine of the scapula ldquolow-barrdquo It has been shown that the low-bar squat is characterized
by more forward lean of the trunk (12) and that powerlifters use the low-bar squatting
technique since this enables them to lift heavier loads (29) The weightlifters mainly use the
high-bar technique which more simulates the movement during their snatch and clean and
jerk competition During competition the weightlifters use the front-squat movement which
is done in an upright position since they cannot balance the weight with too much forward
lean of the trunk Athletes other than lifters may use techniques that are not strictly defined
It is known that injury may occur by overloading the knee joint (1) and also that
squatting generates high forces which can result in serious injuries (1628) During the jerk
dip in weightlifting competition with its large acceleration serious injuries also have occurred
(33) Whether there is a difference in loading moments of force on the hip and knee between
the high- and low-bar squat is however not known but this is of interest eg when
planning the training after an injury In this study we analyze how high- and low-bar squats
effect hip and knee load and the thigh muscle activity Studies such as this offer one way of
improving our knowledge of the biomechanical effects of different training methods
METHOD
Subjects
Eight weightlifters and six powerlifters all of Swedish national class in their age and
bodyweight categories participated in the study Written informed consent was obtained
from the subjects The mean age of the weightlifters was 19 yr (SD plusmn 3) and their mean
weight was 82 kg (SDplusmn 11) The mean age of the powerlifters was 31 yr (SD plusmn 3) and their
mean weight was 87 kg (SD plusmn 20) (Table 1) One of the weightlifters had pain in the knees
due to previous overstrain but he felt it did not affect the way he performed the squat with
the moderate weights used in this study All other lifters were without dysfunction in the
locomotor system
TABLE 1 Subject data 1 RM is the subjects one-repetition maximum for the deep squat
Procedure
The weightlifters performed high-bar squats and the powerlifters performed low-bar
squats We did not let all lifters do both high- and low-bar squats since by testing some of the
lifters we realized that they could not perform the type of squat they were not used to in an
optimal way Two different types of squatting depths were also studied the parallel squat and
the deep squat During the parallel squat the knees were flexed until the posterior borders of
the hamstrings muscles were parallel to the floor and during the deep squat the knees were
maximally flexed Before starting the parallel squat the appropriate squatting depth was
indicated with a non-weight-bearing stop bar beneath the subjects buttocks During the
indicated with a non-weight-bearing stop bar beneath the subjects buttocks During the
movement the subjects flexed their knees until contact was made with the bar All
movements were performed on a force plate (60 times 30 cm) where the feet were placed
symmetrically They could freely choose their stance with and no subject felt restricted by
the 60-cm width of the force plate The bar weight was individually based on the subjects all
time one-repetition maximum (1 RM) for a deep squat exercise as reported by the subjects
A weight of 65 of the 1 RM was chosen None of the lifters wore wraps or belts since this
could have effects on the calculation of the moment of force and since it has been shown that
belts can decrease the electromyographic activity during squatting (20) One of the
weightlifters performing a deep squat is shown in Figure 1
Figure 1-Weightlifter performing a deep squat high-bar technique
For motion analyses a video camera (Panasonic MS1 frame rate 25 Hz with high speed
shutter 11000) and a video recorder (Panasonic 8500) were used The camera was placed to
the left of all subjects at a focal distance of 8 m For synchronization of the force recordings
and the video the computer was triggered by an optical time indication panel visible on the
video recording Skin markers were placed at five places on the body trunk (mid-axillar line
at umbilicus height) hip (superior part of greater trochanter) knee (lateral epicondyle)
ankle (lateral malleolus) and foot (head of fifth metatarsal) The coordinates for these
markers were extracted frame-by-frame from the video recordings with a video position
analyzer (FOR-A company VPA 1000)
The ground reaction forces on the feet were measured with a Kistler multi-component
piezoelectric platform (type 9281 B) which measured the vertical anteroposterior and
piezoelectric platform (type 9281 B) which measured the vertical anteroposterior and
lateral ground reaction forces during rising All force signals (sampled at 100 Hz) were
channelled through Kistler amplifying units (type 5006) to a microcomputer (Luxor ABC 800)
where they were AD converted and stored The position of the center of pressure of the
reaction force between the feet and the ground was also obtained from the force plate
Combining these data with the video coordinates gave the appropriate sagittal moment arms
with respect to the hip and knee joint markers Dempsters anthropometrical data (6) were
used to determine the segmental masses and their mass center locations
A computer program based on free-body mechanics was designed to calculate the
moments of force about the hip (superior part of greater trochanter) and knee (center of
lateral epicondyle) by multiplying each external force (body segment weight or horizontal or
vertical reaction force) by its moment arm length (Fig 2) A ldquosemidynamicrdquo method was
used which incorporated ground reaction forces measured from a force plate and
gravitational contributions from body segments Semidynamic methods have proved to give
results very close to calculation with fully dynamic methods (21) McLaughlin et al (23) and
Lander et al (19) have also analyzed torques and joint forces for squat movements with both
dynamic and semidynamic methods and they found only minor differences indicating that
this kind of method is adequate for these calculations These studies show that the inertial
forces are low compared with the ground reaction forces Similar methods for calculation of
moment of force have been used earlier (5926) and this particular system has been used in
several investigations (eg 31) The same type of technique has also been used in similar
weightlifting studies (210) but fully dynamic methods also are used in weightlifting studies
(11) The patellofemoral compressive force during the parallel squat was calculated using our
moment of force data and diagrams previously published by Nisell and Ekholm (27)
Figure 2-Calculation of the moment of force about the hip(MH) RX and RY are the
horizontal and vertical components of the reaction force from the force plate WT WS
and WF are the segmental weights of thigh shank and foot (XH YH) are the X and Y
cordinates for the marker on the hip joint(XT YT) (XS YS) and (XF YF) are the X and
Y coordinates for the center of gravity of the thigh shank and foot XR and YR are the X
and Y coordinates of the application point of the reaction force
The activity in the vastus lateralis rectus femoris and the long head of the biceps
femoris muscles was recorded (Devices M4 AC8) by means of full-wave rectified low-pass-
filtered and time-averaged electromyogram (linear envelope EMG) The low-pass time
constant was 100 ms Surface (AgAgCl) electrodes were placed on the skin over the muscles
in the fibers direction with an inter-electrode distance of 2 cm For control of artifacts
direct EMG was visualized in parallel on an oscilloscope (Tektronix RM565)
To quantify the muscular activity and to compare the activity between different squats
the EMG activity during the movements was related to a static reference action As reference
contraction a parallel squat with a barbell weight of 65 of 1 RM was chosen The peak EMG
value during a 3-s static parallel position was used as the reference value The muscular
activity is expressed as a quotient of the reference value Normalization like this has been
used earlier (7817)
Statistics
Since the data were approximately normally distributed and since this type of data in
general is known to be normally distributed the parametrict test was used for the statistical
analysis Comparison was done between parallel and deep squats within each group and
between powerlifters and weightlifters for the parallel and deep squat respectively For the
comparison between weightlifters and powerlifters one has to be aware of the differences in
groups concerning body weights and lifted weights
RESULTS
Moments of Force
The joint moment of force curves for one weightlifter and one powerlifter are shown in
Figure 3 All flexing loading moments of force are expressed as positive which means that
the curves describe mainly flexing loading moments for both the hip and the knee These
flexing moments are counteracted by the extensor muscles producing extending moments on
the hip and knee joints The calculated moments are the net muscular moments the effects
of antagonistic muscular activity are not considered The distinct peaks on the curves
correspond to the turning point during the change from knee flexion to knee extension The
two lifters have different load distributions The powerlifter put relatively more load on the
hip joint than on the knee joint while the weightlifter had a more equal distribution of load
between hip and knee
Figure 3-Individual moment curves for one weightlifter and one powerlifter performing a
deep squat Flexing loading moment of force are expressed as positive
Figure 4 shows the mean maximum moments of force for the hip and knee joints for the
different lifters during both the parallel squat and the deep squat Also the mean moment
data show that the weightlifters have a more equal load distribution between hip and knee
than the powerlifters The mean maximum moment at the hip joint was for the powerlifters
324 Nm (deep) and 309 Nm (parallel) The corresponding values for the weightlifters were 230
Nm (deep) and 216 Nm (parallel) The powerlifters had a significantly higher hip moment of
force both for the parallel and deep squat (P lt 005) The differences between the parallel
and the deep squats within each group were not significant At the knee joint there was a
different situation Although the powerlifters were heavier and lifted heavier loads than the
weightlifters they showed the lowest moment of force both for the parallel and the deep
squats and the difference was significant(P lt 005) for the parallel squat The mean
maximum moments were for the powerlifters 139 Nm (deep) and 92 Nm (parallel) For the
weightlifters the mean maximum flexing knee moments were 191 Nm (deep) and 131 Nm
(parallel) Independent of technique the load on the knees increased significantly with
increasing squatting depth (P lt 0005)
Figure 4-Mean maximum moment of force with 95 confidence interval on the hip and
knee joints for the weightlifters and powerlifters during parallel squat and deep squat
(WE N = 8 PON = 6)
The weightlifters showed positive correlation between hip load and the total mass of lifter
and barbell The strongest correlation was found for the deep squat (r = 092) but the
correlation was also significant for the parallel squat (r = 088 P lt 001) There was also a
tendency to positive correlation between hip load and total mass for the powerlifters both for
the parallel (r = 075) and the deep (r = 076) squat but with only six lifters the correlation
was not significant The corresponding values for the knee joint showed that the moments of
force did not increase proportionally with external load This has been found earlier for world
class weightlifters (2)
Knee Forces
We thought it would be interesting to calculate one force component in the knee that
would reflect the magnitudes of the forces in the knee during squatting Therefore the
patello-femoral compression force for the parallel squat was calculated The mean peak
compression force for the weightlifters was 4700 N (SD plusmn 590) and for the powerlifters 3300 N
(SD plusmn 1700) (26)
Electromyography
The muscular activity in the vastus lateralis the rectus femoris and the biceps femoris
muscles was recorded and the mean muscular activity peaks with 95 confidence intervals
are shown in Figure 5 For all muscles and both the parallel and the deep squat the mean peak
muscular activity was higher for the powerlifters However in this study with six powerlifters
and eight weightlifters a significant difference was found only for the rectus femoris muscle
(P lt 005) The highest activity levels both for the weightlifters and the powerlifters were
found for the biceps femoris muscle with a relative muscular activity of about three times
the reference level However the activity in this muscle also showed the greatest individual
difference
Figure 5-Mean maximum muscular activity for the three muscles studied with 95
confidence interval 10 corresponds to the activity during the static reference
contraction (WE N = 8 PON = 6)
Movement and Joint Angles
The knee flexion angles were slightly smaller for the powerlifters The mean knee flexion
angle for the powerlifters were 111deg (SD plusmn 5) for the parallel and 126deg (SD plusmn 4) for the deep
squat The corresponding angles for the weightlifters was 116deg (SD plusmn 5) for the parallel and
138deg (SD plusmn 3) for the deep squat Analyses of the hip flexion angles show that both the
weightlifters and the powerlifters increased these angles with increasing squating depth The
mean maximal hip flexion angles for the weightlifters was 111deg (SD plusmn 8) during the parallel
squat and 125deg (SD plusmn 4) during the deep squat The corresponding angles for the power lifters
were 132deg (SD plusmn 4) and 146deg (SD plusmn 3) respectively By flexing the hip more the powerlifters
leaned the trunk farther forward (Fig 6)
Figure 6-Schematic drawing of the lowest position during the parallel squat A)
weightlifter B) powerlifter Measured angles are indicated the horizontal line indicates
the position of the thigh
DISCUSSION
Since squatting exercise is an important part of the strength training for many athletes
it is important to understand the effects of different squatting techniques In this study we
used weightlifters and powerlifters to demonstrate effects of the high- and low-bar squats
We are aware that there is a difference in age between the two lifter categories but the
analysis showed no difference in principle muscular activity or load between the oldest and
youngest lifters in each group
The study shows the differences between the high- and low-bar techniques and also the
effects on the hip and knee moment of force The low-bar squat with the barbell further
down on the back is characterized of a larger hip flexion (Fig 6) and this technique creates a
hip moment of force that in Newton-meter is almost twice as large as the knee moment The
high-bar squat however is performed more upright and the joint moment of force are more
equally distributed between the hip and knee joints The hip and knee angles in the present
study correlate well with the angles found by Fry et al (12) and confirm the more upright
position during the high-bar squat Although the powerlifters were larger and lifted heavier
loads than the weightlifters the mean moment of force on the knee joint was lower than for
the weightlifter and the difference was significant for the parallel squat The powerlifters
however had significantly a higher load on the hip joint compared with the weightlifters The
difference in hip load could be an effect of heavier lifters lifting heavier loads in addition to
an effect of different technique but the difference in knee moment of force could hardly be
explained from anything else but different lifting technique It is clear that weightlifter
coaches want the squat to be done as upright as possible This is the only way to approach the
movement during weightlifting competition Powerlifting coaches however want lifters to lift
as much as possible with hip and back since by experience they know that this enables the
lifter to lift heavier loads The calculated moment of force on the joint is dependent on the
size of the ground reaction force and the distance between this force and the joint center
the moment arm By increasing hip flexion the powerlifters manage to balance the weight
closer to the knee and thereby reduce the moment arm The moment arm between the
ground reaction force and the hip joint however will increase creating a higher moment of
force on this joint The high-bar squat is performed in a more balanced way where both the
barbell and the trunk center of gravity are centered between hip and knee and thereby the
moments of force are more equally distributed
The powerlifters showed higher EMG activity than the weightlifters for all investigated
muscles although the difference was significant only for the rectus femoris The powerlifters
were heavier and lifted heavier loads but this could be the explanation to the higher muscular
activity EMG activity however was normalized in relation to a reference contraction with
the same relative external load which might indicate that the low-bar squat actually is
advantageous from a muscular recruitment point of view It is clear however that
weightlifters must train with a technique close to the competition situation which means the
high-bar squat Some other athletes might benefit from using a technique close to the low-bar
squat providing that they have the low back strength to safely perform a low bar squat
It is a little surprising that powerlifters performing low-bar squats with relatively low
moment of force at the knee joints have a knee extensor muscular activity even slightly
higher than weightlifters performing high-bar squats with higher knee moments The
explanation must be that the moments calculated are net loading moments of force which
means that muscular co-contraction is not included in the values calculated The activity in the
biceps femoris muscle is slightly higher for the low-bar squat The activity in the
gastrocnemius muscle and the soleus muscle was not recorded However since the low-bar
squat is performed with the total center of gravity further forward the need for
compensatory ankle plantar flexion will increase which means increased activity in both the
gastrocnemius and the soleus muscles During the low-bar squat knee flexor muscle activity
increases and hereby knee extensor co-contraction This can explain why the knee extensor
activity is high despite the relatively low net knee loading moment As previously mentioned
one should be aware that the calculated moments are net moments of force and that the
effect of co-contracting antagonistic muscles are not taken into account A antagonistic
moment of force created by the antagonist would increase the moment of force produced by
the agonists Therefore the moment calculated in this study must be taken as minimum
loading moments for the agonists Two joint muscles can in this way serve as agonist at one
of the joints and antagonists at an other The biceps femoris for example produce an
extending moment of force at the hip but an antagonistic flexing moment of force at the
knee The magnitude of this antagonistic moment is not possible to calculate in a study like
this
Although hip extensor activity was not analyzed it seems logical that the low-bar squat
should be the best technique concerning hip extensor training since this technique create the
greatest moments of force at the joint
The patello-femoral compression force was calculated to give an apprehension of the
force magnitudes Forces in the hip and knee depend not only on the moment of force but
also on joint angle (222425) For a constant moment of force joint compression forces
increase with increasing flexion angle This has been investigated for hip flexion up to 90deg and
for knee flexion up to 120deg For the knee the patello-femoral compression force levels away
between 90 and 120deg So the reason for larger compression force in the knee for the
weightliftres was not because of a larger knee flexion angles rather related to the larger
moment of force
Both the weightlifters and powerlifters have a strict and precise squatting technique It is
probable that many other athletes in other disciplines use techniques in between the high- and
low-bar techniques and that their coaches are not aware of the effects of the different
techniques Athletes should benefit from studying lifters and their technique and the different
effects that can be achieved It is known that squatting exercise is a good method for knee
rehabilitation training (30) and we suggest that after a hip injury high-bar squat should be
used at the beginning to minimize the risk of hip overload After a knee injury a squatting
technique more similar to the low-bar technique should be preferred Further investigation
on for example shear and compression forces on the lumbar spine during the two different
types of squatting technique must be important to prevent reinjury of the lower back during
rehabilitation exercise
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1988 [Context Link]
3 Chandler T J and M H Stone The squat exercise in athletic conditioning a review of
the literature Natl Strength Condit Assoc J 1352-58 1991 [Context Link]
4 Coaches Roundtable The squat and its application to athletic performance Natl Strength
Condit Assoc J 610-22 1984 [Context Link]
5 Dahlkvist N J P Mayo and B B Seedhom Forces during squatting and rising from a
deep squat Eng Med 269-76 1982 [Context Link]
6 Dempster W T and G R L Gaughran Properties of body segments based on size and
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7 Ekholm J R Nisell U P Arborelius C Hammarberg and G Nemeth Load on knee
joint structures and muscular activity during lifting Scand J Rehabil Med 161-9 1984
Bibliographic Links [Context Link]
8 Ekholm J R Nisell U P Arborelius O Svensson and G Nemeth Load on knee joint
and knee muscular activity during machine milking Ergonomics 4665-682 1985
Bibliographic Links [Context Link]
9 Ellis M I B B Seedhom A A Amis D Dowson and V Wright Forces in the knee joint
whilst rising from normal and motorized chairs Eng Med 133-40 1979 [Context Link]
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Link]
11 Enoka R M Load- and skill-related changes in segmental contributions to a weightlifting
movement Med Sci Sports Exerc 2178-187 1988 [Context Link]
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determining kinematic properties of three barbell squat exercises J Hum Mov Stud 2483-
95 1993 [Context Link]
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287 1979 [Context Link]
14 Garhammer J Power production by olympic weightlifters Med Sci Sports Exerc 154-
60 1980 [Context Link]
15 Garhammer J Biomechanical profiles of olympic weightlifters Int J Sports Biomech
1122-130 1985 [Context Link]
16 Grenier R and A Guimont Simultaneous bilateral rupture of the quadriceps tendon and
leg fractures in a weightlifterAm J Sports Med 6451-453 1983 Bibliographic Links
[Context Link]
[Context Link]
17 Hammarskjoumlld E K Harms-Ringdahl and J Ekholm Shoulder-arm muscular activity and
reproducibility in carpenters work Clin Biomech 581-87 1990 Bibliographic Links
[Context Link]
18 Hattin H C M R Pierrynowski and K A Ball Effect of load cadence and fatigue on
tibio-femoral joint force during a half squat Med Sci Sports Exerc 5613-618 1989
[Context Link]
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during the squat exercise Med Sci Sports Exerc 22117-126 1990 Ovid Full Text
Bibliographic Links [Context Link]
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during multiple repetitions of the squat exercise Med Sci Sports Exerc 24603-609 1992
Ovid Full Text Bibliographic Links [Context Link]
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analysis of lifting Ergonomics 4421-433 1991 Bibliographic Links [Context Link]
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2175-189 1978 [Context Link]
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lifting Ergonomics 28429-440 1985 Bibliographic Links [Context Link]
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during lifting Scand J Rehabil Med 16103-111 1984 Bibliographic Links [Context Link]
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joint load and muscular activation during rising exercises Scand J Rehabil Med 1693-102
1984 Bibliographic Links [Context Link]
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1763-74 1985 Bibliographic Links [Context Link]
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WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
IMAGE GALLERY
Table 1
Figure 1-Weightlifte
Figure 2-Calculation
Figure 3-Individual
Figure 4-Mean maximu
Figure 5-Mean maximu
Figure 6-Schematic d
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of squats but that the load on the knee joints is larger for the deep squat
There are two main techniques for the squatting exercise with the bar on the back the
ldquohigh-barrdquo squat and the ldquolow-barrdquo squat (29) The names of the techniques are related to
the placement of the bar on the back The bar is either centered across the shoulders just
below the spinous process of the C7 vertebraldquohigh-barrdquo or further down on the back across
the spine of the scapula ldquolow-barrdquo It has been shown that the low-bar squat is characterized
by more forward lean of the trunk (12) and that powerlifters use the low-bar squatting
technique since this enables them to lift heavier loads (29) The weightlifters mainly use the
high-bar technique which more simulates the movement during their snatch and clean and
jerk competition During competition the weightlifters use the front-squat movement which
is done in an upright position since they cannot balance the weight with too much forward
lean of the trunk Athletes other than lifters may use techniques that are not strictly defined
It is known that injury may occur by overloading the knee joint (1) and also that
squatting generates high forces which can result in serious injuries (1628) During the jerk
dip in weightlifting competition with its large acceleration serious injuries also have occurred
(33) Whether there is a difference in loading moments of force on the hip and knee between
the high- and low-bar squat is however not known but this is of interest eg when
planning the training after an injury In this study we analyze how high- and low-bar squats
effect hip and knee load and the thigh muscle activity Studies such as this offer one way of
improving our knowledge of the biomechanical effects of different training methods
METHOD
Subjects
Eight weightlifters and six powerlifters all of Swedish national class in their age and
bodyweight categories participated in the study Written informed consent was obtained
from the subjects The mean age of the weightlifters was 19 yr (SD plusmn 3) and their mean
weight was 82 kg (SDplusmn 11) The mean age of the powerlifters was 31 yr (SD plusmn 3) and their
mean weight was 87 kg (SD plusmn 20) (Table 1) One of the weightlifters had pain in the knees
due to previous overstrain but he felt it did not affect the way he performed the squat with
the moderate weights used in this study All other lifters were without dysfunction in the
locomotor system
TABLE 1 Subject data 1 RM is the subjects one-repetition maximum for the deep squat
Procedure
The weightlifters performed high-bar squats and the powerlifters performed low-bar
squats We did not let all lifters do both high- and low-bar squats since by testing some of the
lifters we realized that they could not perform the type of squat they were not used to in an
optimal way Two different types of squatting depths were also studied the parallel squat and
the deep squat During the parallel squat the knees were flexed until the posterior borders of
the hamstrings muscles were parallel to the floor and during the deep squat the knees were
maximally flexed Before starting the parallel squat the appropriate squatting depth was
indicated with a non-weight-bearing stop bar beneath the subjects buttocks During the
indicated with a non-weight-bearing stop bar beneath the subjects buttocks During the
movement the subjects flexed their knees until contact was made with the bar All
movements were performed on a force plate (60 times 30 cm) where the feet were placed
symmetrically They could freely choose their stance with and no subject felt restricted by
the 60-cm width of the force plate The bar weight was individually based on the subjects all
time one-repetition maximum (1 RM) for a deep squat exercise as reported by the subjects
A weight of 65 of the 1 RM was chosen None of the lifters wore wraps or belts since this
could have effects on the calculation of the moment of force and since it has been shown that
belts can decrease the electromyographic activity during squatting (20) One of the
weightlifters performing a deep squat is shown in Figure 1
Figure 1-Weightlifter performing a deep squat high-bar technique
For motion analyses a video camera (Panasonic MS1 frame rate 25 Hz with high speed
shutter 11000) and a video recorder (Panasonic 8500) were used The camera was placed to
the left of all subjects at a focal distance of 8 m For synchronization of the force recordings
and the video the computer was triggered by an optical time indication panel visible on the
video recording Skin markers were placed at five places on the body trunk (mid-axillar line
at umbilicus height) hip (superior part of greater trochanter) knee (lateral epicondyle)
ankle (lateral malleolus) and foot (head of fifth metatarsal) The coordinates for these
markers were extracted frame-by-frame from the video recordings with a video position
analyzer (FOR-A company VPA 1000)
The ground reaction forces on the feet were measured with a Kistler multi-component
piezoelectric platform (type 9281 B) which measured the vertical anteroposterior and
piezoelectric platform (type 9281 B) which measured the vertical anteroposterior and
lateral ground reaction forces during rising All force signals (sampled at 100 Hz) were
channelled through Kistler amplifying units (type 5006) to a microcomputer (Luxor ABC 800)
where they were AD converted and stored The position of the center of pressure of the
reaction force between the feet and the ground was also obtained from the force plate
Combining these data with the video coordinates gave the appropriate sagittal moment arms
with respect to the hip and knee joint markers Dempsters anthropometrical data (6) were
used to determine the segmental masses and their mass center locations
A computer program based on free-body mechanics was designed to calculate the
moments of force about the hip (superior part of greater trochanter) and knee (center of
lateral epicondyle) by multiplying each external force (body segment weight or horizontal or
vertical reaction force) by its moment arm length (Fig 2) A ldquosemidynamicrdquo method was
used which incorporated ground reaction forces measured from a force plate and
gravitational contributions from body segments Semidynamic methods have proved to give
results very close to calculation with fully dynamic methods (21) McLaughlin et al (23) and
Lander et al (19) have also analyzed torques and joint forces for squat movements with both
dynamic and semidynamic methods and they found only minor differences indicating that
this kind of method is adequate for these calculations These studies show that the inertial
forces are low compared with the ground reaction forces Similar methods for calculation of
moment of force have been used earlier (5926) and this particular system has been used in
several investigations (eg 31) The same type of technique has also been used in similar
weightlifting studies (210) but fully dynamic methods also are used in weightlifting studies
(11) The patellofemoral compressive force during the parallel squat was calculated using our
moment of force data and diagrams previously published by Nisell and Ekholm (27)
Figure 2-Calculation of the moment of force about the hip(MH) RX and RY are the
horizontal and vertical components of the reaction force from the force plate WT WS
and WF are the segmental weights of thigh shank and foot (XH YH) are the X and Y
cordinates for the marker on the hip joint(XT YT) (XS YS) and (XF YF) are the X and
Y coordinates for the center of gravity of the thigh shank and foot XR and YR are the X
and Y coordinates of the application point of the reaction force
The activity in the vastus lateralis rectus femoris and the long head of the biceps
femoris muscles was recorded (Devices M4 AC8) by means of full-wave rectified low-pass-
filtered and time-averaged electromyogram (linear envelope EMG) The low-pass time
constant was 100 ms Surface (AgAgCl) electrodes were placed on the skin over the muscles
in the fibers direction with an inter-electrode distance of 2 cm For control of artifacts
direct EMG was visualized in parallel on an oscilloscope (Tektronix RM565)
To quantify the muscular activity and to compare the activity between different squats
the EMG activity during the movements was related to a static reference action As reference
contraction a parallel squat with a barbell weight of 65 of 1 RM was chosen The peak EMG
value during a 3-s static parallel position was used as the reference value The muscular
activity is expressed as a quotient of the reference value Normalization like this has been
used earlier (7817)
Statistics
Since the data were approximately normally distributed and since this type of data in
general is known to be normally distributed the parametrict test was used for the statistical
analysis Comparison was done between parallel and deep squats within each group and
between powerlifters and weightlifters for the parallel and deep squat respectively For the
comparison between weightlifters and powerlifters one has to be aware of the differences in
groups concerning body weights and lifted weights
RESULTS
Moments of Force
The joint moment of force curves for one weightlifter and one powerlifter are shown in
Figure 3 All flexing loading moments of force are expressed as positive which means that
the curves describe mainly flexing loading moments for both the hip and the knee These
flexing moments are counteracted by the extensor muscles producing extending moments on
the hip and knee joints The calculated moments are the net muscular moments the effects
of antagonistic muscular activity are not considered The distinct peaks on the curves
correspond to the turning point during the change from knee flexion to knee extension The
two lifters have different load distributions The powerlifter put relatively more load on the
hip joint than on the knee joint while the weightlifter had a more equal distribution of load
between hip and knee
Figure 3-Individual moment curves for one weightlifter and one powerlifter performing a
deep squat Flexing loading moment of force are expressed as positive
Figure 4 shows the mean maximum moments of force for the hip and knee joints for the
different lifters during both the parallel squat and the deep squat Also the mean moment
data show that the weightlifters have a more equal load distribution between hip and knee
than the powerlifters The mean maximum moment at the hip joint was for the powerlifters
324 Nm (deep) and 309 Nm (parallel) The corresponding values for the weightlifters were 230
Nm (deep) and 216 Nm (parallel) The powerlifters had a significantly higher hip moment of
force both for the parallel and deep squat (P lt 005) The differences between the parallel
and the deep squats within each group were not significant At the knee joint there was a
different situation Although the powerlifters were heavier and lifted heavier loads than the
weightlifters they showed the lowest moment of force both for the parallel and the deep
squats and the difference was significant(P lt 005) for the parallel squat The mean
maximum moments were for the powerlifters 139 Nm (deep) and 92 Nm (parallel) For the
weightlifters the mean maximum flexing knee moments were 191 Nm (deep) and 131 Nm
(parallel) Independent of technique the load on the knees increased significantly with
increasing squatting depth (P lt 0005)
Figure 4-Mean maximum moment of force with 95 confidence interval on the hip and
knee joints for the weightlifters and powerlifters during parallel squat and deep squat
(WE N = 8 PON = 6)
The weightlifters showed positive correlation between hip load and the total mass of lifter
and barbell The strongest correlation was found for the deep squat (r = 092) but the
correlation was also significant for the parallel squat (r = 088 P lt 001) There was also a
tendency to positive correlation between hip load and total mass for the powerlifters both for
the parallel (r = 075) and the deep (r = 076) squat but with only six lifters the correlation
was not significant The corresponding values for the knee joint showed that the moments of
force did not increase proportionally with external load This has been found earlier for world
class weightlifters (2)
Knee Forces
We thought it would be interesting to calculate one force component in the knee that
would reflect the magnitudes of the forces in the knee during squatting Therefore the
patello-femoral compression force for the parallel squat was calculated The mean peak
compression force for the weightlifters was 4700 N (SD plusmn 590) and for the powerlifters 3300 N
(SD plusmn 1700) (26)
Electromyography
The muscular activity in the vastus lateralis the rectus femoris and the biceps femoris
muscles was recorded and the mean muscular activity peaks with 95 confidence intervals
are shown in Figure 5 For all muscles and both the parallel and the deep squat the mean peak
muscular activity was higher for the powerlifters However in this study with six powerlifters
and eight weightlifters a significant difference was found only for the rectus femoris muscle
(P lt 005) The highest activity levels both for the weightlifters and the powerlifters were
found for the biceps femoris muscle with a relative muscular activity of about three times
the reference level However the activity in this muscle also showed the greatest individual
difference
Figure 5-Mean maximum muscular activity for the three muscles studied with 95
confidence interval 10 corresponds to the activity during the static reference
contraction (WE N = 8 PON = 6)
Movement and Joint Angles
The knee flexion angles were slightly smaller for the powerlifters The mean knee flexion
angle for the powerlifters were 111deg (SD plusmn 5) for the parallel and 126deg (SD plusmn 4) for the deep
squat The corresponding angles for the weightlifters was 116deg (SD plusmn 5) for the parallel and
138deg (SD plusmn 3) for the deep squat Analyses of the hip flexion angles show that both the
weightlifters and the powerlifters increased these angles with increasing squating depth The
mean maximal hip flexion angles for the weightlifters was 111deg (SD plusmn 8) during the parallel
squat and 125deg (SD plusmn 4) during the deep squat The corresponding angles for the power lifters
were 132deg (SD plusmn 4) and 146deg (SD plusmn 3) respectively By flexing the hip more the powerlifters
leaned the trunk farther forward (Fig 6)
Figure 6-Schematic drawing of the lowest position during the parallel squat A)
weightlifter B) powerlifter Measured angles are indicated the horizontal line indicates
the position of the thigh
DISCUSSION
Since squatting exercise is an important part of the strength training for many athletes
it is important to understand the effects of different squatting techniques In this study we
used weightlifters and powerlifters to demonstrate effects of the high- and low-bar squats
We are aware that there is a difference in age between the two lifter categories but the
analysis showed no difference in principle muscular activity or load between the oldest and
youngest lifters in each group
The study shows the differences between the high- and low-bar techniques and also the
effects on the hip and knee moment of force The low-bar squat with the barbell further
down on the back is characterized of a larger hip flexion (Fig 6) and this technique creates a
hip moment of force that in Newton-meter is almost twice as large as the knee moment The
high-bar squat however is performed more upright and the joint moment of force are more
equally distributed between the hip and knee joints The hip and knee angles in the present
study correlate well with the angles found by Fry et al (12) and confirm the more upright
position during the high-bar squat Although the powerlifters were larger and lifted heavier
loads than the weightlifters the mean moment of force on the knee joint was lower than for
the weightlifter and the difference was significant for the parallel squat The powerlifters
however had significantly a higher load on the hip joint compared with the weightlifters The
difference in hip load could be an effect of heavier lifters lifting heavier loads in addition to
an effect of different technique but the difference in knee moment of force could hardly be
explained from anything else but different lifting technique It is clear that weightlifter
coaches want the squat to be done as upright as possible This is the only way to approach the
movement during weightlifting competition Powerlifting coaches however want lifters to lift
as much as possible with hip and back since by experience they know that this enables the
lifter to lift heavier loads The calculated moment of force on the joint is dependent on the
size of the ground reaction force and the distance between this force and the joint center
the moment arm By increasing hip flexion the powerlifters manage to balance the weight
closer to the knee and thereby reduce the moment arm The moment arm between the
ground reaction force and the hip joint however will increase creating a higher moment of
force on this joint The high-bar squat is performed in a more balanced way where both the
barbell and the trunk center of gravity are centered between hip and knee and thereby the
moments of force are more equally distributed
The powerlifters showed higher EMG activity than the weightlifters for all investigated
muscles although the difference was significant only for the rectus femoris The powerlifters
were heavier and lifted heavier loads but this could be the explanation to the higher muscular
activity EMG activity however was normalized in relation to a reference contraction with
the same relative external load which might indicate that the low-bar squat actually is
advantageous from a muscular recruitment point of view It is clear however that
weightlifters must train with a technique close to the competition situation which means the
high-bar squat Some other athletes might benefit from using a technique close to the low-bar
squat providing that they have the low back strength to safely perform a low bar squat
It is a little surprising that powerlifters performing low-bar squats with relatively low
moment of force at the knee joints have a knee extensor muscular activity even slightly
higher than weightlifters performing high-bar squats with higher knee moments The
explanation must be that the moments calculated are net loading moments of force which
means that muscular co-contraction is not included in the values calculated The activity in the
biceps femoris muscle is slightly higher for the low-bar squat The activity in the
gastrocnemius muscle and the soleus muscle was not recorded However since the low-bar
squat is performed with the total center of gravity further forward the need for
compensatory ankle plantar flexion will increase which means increased activity in both the
gastrocnemius and the soleus muscles During the low-bar squat knee flexor muscle activity
increases and hereby knee extensor co-contraction This can explain why the knee extensor
activity is high despite the relatively low net knee loading moment As previously mentioned
one should be aware that the calculated moments are net moments of force and that the
effect of co-contracting antagonistic muscles are not taken into account A antagonistic
moment of force created by the antagonist would increase the moment of force produced by
the agonists Therefore the moment calculated in this study must be taken as minimum
loading moments for the agonists Two joint muscles can in this way serve as agonist at one
of the joints and antagonists at an other The biceps femoris for example produce an
extending moment of force at the hip but an antagonistic flexing moment of force at the
knee The magnitude of this antagonistic moment is not possible to calculate in a study like
this
Although hip extensor activity was not analyzed it seems logical that the low-bar squat
should be the best technique concerning hip extensor training since this technique create the
greatest moments of force at the joint
The patello-femoral compression force was calculated to give an apprehension of the
force magnitudes Forces in the hip and knee depend not only on the moment of force but
also on joint angle (222425) For a constant moment of force joint compression forces
increase with increasing flexion angle This has been investigated for hip flexion up to 90deg and
for knee flexion up to 120deg For the knee the patello-femoral compression force levels away
between 90 and 120deg So the reason for larger compression force in the knee for the
weightliftres was not because of a larger knee flexion angles rather related to the larger
moment of force
Both the weightlifters and powerlifters have a strict and precise squatting technique It is
probable that many other athletes in other disciplines use techniques in between the high- and
low-bar techniques and that their coaches are not aware of the effects of the different
techniques Athletes should benefit from studying lifters and their technique and the different
effects that can be achieved It is known that squatting exercise is a good method for knee
rehabilitation training (30) and we suggest that after a hip injury high-bar squat should be
used at the beginning to minimize the risk of hip overload After a knee injury a squatting
technique more similar to the low-bar technique should be preferred Further investigation
on for example shear and compression forces on the lumbar spine during the two different
types of squatting technique must be important to prevent reinjury of the lower back during
rehabilitation exercise
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load In Biomechanics IV A J Nelson and C A Morehouse (Eds) Baltimore University
Park Press 1975 pp 44-52 [Context Link]
2 Baumann W V Gross K Quade P Galbierz and A Schwirtz The snatch technique of
world class weightlifters at the 1985 world championships Int J Sprots Biomech 468-89
1988 [Context Link]
3 Chandler T J and M H Stone The squat exercise in athletic conditioning a review of
the literature Natl Strength Condit Assoc J 1352-58 1991 [Context Link]
4 Coaches Roundtable The squat and its application to athletic performance Natl Strength
Condit Assoc J 610-22 1984 [Context Link]
5 Dahlkvist N J P Mayo and B B Seedhom Forces during squatting and rising from a
deep squat Eng Med 269-76 1982 [Context Link]
6 Dempster W T and G R L Gaughran Properties of body segments based on size and
weight Am J Anat 12033-54 1967 [Context Link]
7 Ekholm J R Nisell U P Arborelius C Hammarberg and G Nemeth Load on knee
joint structures and muscular activity during lifting Scand J Rehabil Med 161-9 1984
Bibliographic Links [Context Link]
8 Ekholm J R Nisell U P Arborelius O Svensson and G Nemeth Load on knee joint
and knee muscular activity during machine milking Ergonomics 4665-682 1985
Bibliographic Links [Context Link]
9 Ellis M I B B Seedhom A A Amis D Dowson and V Wright Forces in the knee joint
whilst rising from normal and motorized chairs Eng Med 133-40 1979 [Context Link]
10 Enoka R M The pull in Olympic weightliftingMed Sci Sports 2131-137 1979 [Context
Link]
11 Enoka R M Load- and skill-related changes in segmental contributions to a weightlifting
movement Med Sci Sports Exerc 2178-187 1988 [Context Link]
12 Fry A C T A Aro J A Bauer and W J Kraemer A comparison of methods for
determining kinematic properties of three barbell squat exercises J Hum Mov Stud 2483-
95 1993 [Context Link]
13 Garhammer J Performance evaluation of Olympic weightlifters Med Sci Sports 3284-
287 1979 [Context Link]
14 Garhammer J Power production by olympic weightlifters Med Sci Sports Exerc 154-
60 1980 [Context Link]
15 Garhammer J Biomechanical profiles of olympic weightlifters Int J Sports Biomech
1122-130 1985 [Context Link]
16 Grenier R and A Guimont Simultaneous bilateral rupture of the quadriceps tendon and
leg fractures in a weightlifterAm J Sports Med 6451-453 1983 Bibliographic Links
[Context Link]
[Context Link]
17 Hammarskjoumlld E K Harms-Ringdahl and J Ekholm Shoulder-arm muscular activity and
reproducibility in carpenters work Clin Biomech 581-87 1990 Bibliographic Links
[Context Link]
18 Hattin H C M R Pierrynowski and K A Ball Effect of load cadence and fatigue on
tibio-femoral joint force during a half squat Med Sci Sports Exerc 5613-618 1989
[Context Link]
19 Lander J F R L Simonton and J K F Giacobbe The effectiveness of weight-belts
during the squat exercise Med Sci Sports Exerc 22117-126 1990 Ovid Full Text
Bibliographic Links [Context Link]
20 Lander J E J R Hundley and R L Simonton The effectiveness of weight-belts
during multiple repetitions of the squat exercise Med Sci Sports Exerc 24603-609 1992
Ovid Full Text Bibliographic Links [Context Link]
21 Lindbeck L and U P Arborelius Inertial effects from single body segments in dynamic
analysis of lifting Ergonomics 4421-433 1991 Bibliographic Links [Context Link]
22 McLaughlin T M C J Dillman and T J Lardner A kinematic model of performance in
the parallel squat by champion powerliftersMed Sci Sports 2128-133 1977 [Context Link]
23 McLaughlin T M T J Lardner and C J Dillman Kinetics of the parallel squat Res Q
2175-189 1978 [Context Link]
24 Nemeth G and J Ekholm A biomechanical analysis of hip compression loading during
lifting Ergonomics 28429-440 1985 Bibliographic Links [Context Link]
25 Nemeth G J Ekholm and U P Arborelius Hip load moments and muscular activity
during lifting Scand J Rehabil Med 16103-111 1984 Bibliographic Links [Context Link]
26 Nemeth G J Ekholm U P Arborelius K Schlt951gtuldt and K Harms-Ringdahl Hip
joint load and muscular activation during rising exercises Scand J Rehabil Med 1693-102
1984 Bibliographic Links [Context Link]
27 Nisell R and J Ekholm Patellar forces during knee extension Scand J Rehabil Med
1763-74 1985 Bibliographic Links [Context Link]
28 Nisell R and J Ekholm Joint load during the parallel squat in powerlifting and forces of
in vivo bilateral quadriceps tendon rupture Scand J Sports Sci 863-70 1986 [Context
Link]
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Select All Export Selected to PowerPoint
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Link]
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rehabilitation Sports Med 11402-413 1991 Ovid Full Text Bibliographic Links [Context
Link]
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alignment and knee joint load(Dissertation) Karolinska Institute Stockholm Sweden 1992
[Context Link]
32 Wretenberg P F Yi F Lindberg and U P Arborelius Joint moment of force and
quadriceps muscle activity during squatting exercise Scand J Med Sci Sports 3244-250
1993 Bibliographic Links [Context Link]
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Bone Joint Surg Am A-59179-183 1977 [Context Link]
WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
IMAGE GALLERY
Table 1
Figure 1-Weightlifte
Figure 2-Calculation
Figure 3-Individual
Figure 4-Mean maximu
Figure 5-Mean maximu
Figure 6-Schematic d
Back to Top
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indicated with a non-weight-bearing stop bar beneath the subjects buttocks During the
movement the subjects flexed their knees until contact was made with the bar All
movements were performed on a force plate (60 times 30 cm) where the feet were placed
symmetrically They could freely choose their stance with and no subject felt restricted by
the 60-cm width of the force plate The bar weight was individually based on the subjects all
time one-repetition maximum (1 RM) for a deep squat exercise as reported by the subjects
A weight of 65 of the 1 RM was chosen None of the lifters wore wraps or belts since this
could have effects on the calculation of the moment of force and since it has been shown that
belts can decrease the electromyographic activity during squatting (20) One of the
weightlifters performing a deep squat is shown in Figure 1
Figure 1-Weightlifter performing a deep squat high-bar technique
For motion analyses a video camera (Panasonic MS1 frame rate 25 Hz with high speed
shutter 11000) and a video recorder (Panasonic 8500) were used The camera was placed to
the left of all subjects at a focal distance of 8 m For synchronization of the force recordings
and the video the computer was triggered by an optical time indication panel visible on the
video recording Skin markers were placed at five places on the body trunk (mid-axillar line
at umbilicus height) hip (superior part of greater trochanter) knee (lateral epicondyle)
ankle (lateral malleolus) and foot (head of fifth metatarsal) The coordinates for these
markers were extracted frame-by-frame from the video recordings with a video position
analyzer (FOR-A company VPA 1000)
The ground reaction forces on the feet were measured with a Kistler multi-component
piezoelectric platform (type 9281 B) which measured the vertical anteroposterior and
piezoelectric platform (type 9281 B) which measured the vertical anteroposterior and
lateral ground reaction forces during rising All force signals (sampled at 100 Hz) were
channelled through Kistler amplifying units (type 5006) to a microcomputer (Luxor ABC 800)
where they were AD converted and stored The position of the center of pressure of the
reaction force between the feet and the ground was also obtained from the force plate
Combining these data with the video coordinates gave the appropriate sagittal moment arms
with respect to the hip and knee joint markers Dempsters anthropometrical data (6) were
used to determine the segmental masses and their mass center locations
A computer program based on free-body mechanics was designed to calculate the
moments of force about the hip (superior part of greater trochanter) and knee (center of
lateral epicondyle) by multiplying each external force (body segment weight or horizontal or
vertical reaction force) by its moment arm length (Fig 2) A ldquosemidynamicrdquo method was
used which incorporated ground reaction forces measured from a force plate and
gravitational contributions from body segments Semidynamic methods have proved to give
results very close to calculation with fully dynamic methods (21) McLaughlin et al (23) and
Lander et al (19) have also analyzed torques and joint forces for squat movements with both
dynamic and semidynamic methods and they found only minor differences indicating that
this kind of method is adequate for these calculations These studies show that the inertial
forces are low compared with the ground reaction forces Similar methods for calculation of
moment of force have been used earlier (5926) and this particular system has been used in
several investigations (eg 31) The same type of technique has also been used in similar
weightlifting studies (210) but fully dynamic methods also are used in weightlifting studies
(11) The patellofemoral compressive force during the parallel squat was calculated using our
moment of force data and diagrams previously published by Nisell and Ekholm (27)
Figure 2-Calculation of the moment of force about the hip(MH) RX and RY are the
horizontal and vertical components of the reaction force from the force plate WT WS
and WF are the segmental weights of thigh shank and foot (XH YH) are the X and Y
cordinates for the marker on the hip joint(XT YT) (XS YS) and (XF YF) are the X and
Y coordinates for the center of gravity of the thigh shank and foot XR and YR are the X
and Y coordinates of the application point of the reaction force
The activity in the vastus lateralis rectus femoris and the long head of the biceps
femoris muscles was recorded (Devices M4 AC8) by means of full-wave rectified low-pass-
filtered and time-averaged electromyogram (linear envelope EMG) The low-pass time
constant was 100 ms Surface (AgAgCl) electrodes were placed on the skin over the muscles
in the fibers direction with an inter-electrode distance of 2 cm For control of artifacts
direct EMG was visualized in parallel on an oscilloscope (Tektronix RM565)
To quantify the muscular activity and to compare the activity between different squats
the EMG activity during the movements was related to a static reference action As reference
contraction a parallel squat with a barbell weight of 65 of 1 RM was chosen The peak EMG
value during a 3-s static parallel position was used as the reference value The muscular
activity is expressed as a quotient of the reference value Normalization like this has been
used earlier (7817)
Statistics
Since the data were approximately normally distributed and since this type of data in
general is known to be normally distributed the parametrict test was used for the statistical
analysis Comparison was done between parallel and deep squats within each group and
between powerlifters and weightlifters for the parallel and deep squat respectively For the
comparison between weightlifters and powerlifters one has to be aware of the differences in
groups concerning body weights and lifted weights
RESULTS
Moments of Force
The joint moment of force curves for one weightlifter and one powerlifter are shown in
Figure 3 All flexing loading moments of force are expressed as positive which means that
the curves describe mainly flexing loading moments for both the hip and the knee These
flexing moments are counteracted by the extensor muscles producing extending moments on
the hip and knee joints The calculated moments are the net muscular moments the effects
of antagonistic muscular activity are not considered The distinct peaks on the curves
correspond to the turning point during the change from knee flexion to knee extension The
two lifters have different load distributions The powerlifter put relatively more load on the
hip joint than on the knee joint while the weightlifter had a more equal distribution of load
between hip and knee
Figure 3-Individual moment curves for one weightlifter and one powerlifter performing a
deep squat Flexing loading moment of force are expressed as positive
Figure 4 shows the mean maximum moments of force for the hip and knee joints for the
different lifters during both the parallel squat and the deep squat Also the mean moment
data show that the weightlifters have a more equal load distribution between hip and knee
than the powerlifters The mean maximum moment at the hip joint was for the powerlifters
324 Nm (deep) and 309 Nm (parallel) The corresponding values for the weightlifters were 230
Nm (deep) and 216 Nm (parallel) The powerlifters had a significantly higher hip moment of
force both for the parallel and deep squat (P lt 005) The differences between the parallel
and the deep squats within each group were not significant At the knee joint there was a
different situation Although the powerlifters were heavier and lifted heavier loads than the
weightlifters they showed the lowest moment of force both for the parallel and the deep
squats and the difference was significant(P lt 005) for the parallel squat The mean
maximum moments were for the powerlifters 139 Nm (deep) and 92 Nm (parallel) For the
weightlifters the mean maximum flexing knee moments were 191 Nm (deep) and 131 Nm
(parallel) Independent of technique the load on the knees increased significantly with
increasing squatting depth (P lt 0005)
Figure 4-Mean maximum moment of force with 95 confidence interval on the hip and
knee joints for the weightlifters and powerlifters during parallel squat and deep squat
(WE N = 8 PON = 6)
The weightlifters showed positive correlation between hip load and the total mass of lifter
and barbell The strongest correlation was found for the deep squat (r = 092) but the
correlation was also significant for the parallel squat (r = 088 P lt 001) There was also a
tendency to positive correlation between hip load and total mass for the powerlifters both for
the parallel (r = 075) and the deep (r = 076) squat but with only six lifters the correlation
was not significant The corresponding values for the knee joint showed that the moments of
force did not increase proportionally with external load This has been found earlier for world
class weightlifters (2)
Knee Forces
We thought it would be interesting to calculate one force component in the knee that
would reflect the magnitudes of the forces in the knee during squatting Therefore the
patello-femoral compression force for the parallel squat was calculated The mean peak
compression force for the weightlifters was 4700 N (SD plusmn 590) and for the powerlifters 3300 N
(SD plusmn 1700) (26)
Electromyography
The muscular activity in the vastus lateralis the rectus femoris and the biceps femoris
muscles was recorded and the mean muscular activity peaks with 95 confidence intervals
are shown in Figure 5 For all muscles and both the parallel and the deep squat the mean peak
muscular activity was higher for the powerlifters However in this study with six powerlifters
and eight weightlifters a significant difference was found only for the rectus femoris muscle
(P lt 005) The highest activity levels both for the weightlifters and the powerlifters were
found for the biceps femoris muscle with a relative muscular activity of about three times
the reference level However the activity in this muscle also showed the greatest individual
difference
Figure 5-Mean maximum muscular activity for the three muscles studied with 95
confidence interval 10 corresponds to the activity during the static reference
contraction (WE N = 8 PON = 6)
Movement and Joint Angles
The knee flexion angles were slightly smaller for the powerlifters The mean knee flexion
angle for the powerlifters were 111deg (SD plusmn 5) for the parallel and 126deg (SD plusmn 4) for the deep
squat The corresponding angles for the weightlifters was 116deg (SD plusmn 5) for the parallel and
138deg (SD plusmn 3) for the deep squat Analyses of the hip flexion angles show that both the
weightlifters and the powerlifters increased these angles with increasing squating depth The
mean maximal hip flexion angles for the weightlifters was 111deg (SD plusmn 8) during the parallel
squat and 125deg (SD plusmn 4) during the deep squat The corresponding angles for the power lifters
were 132deg (SD plusmn 4) and 146deg (SD plusmn 3) respectively By flexing the hip more the powerlifters
leaned the trunk farther forward (Fig 6)
Figure 6-Schematic drawing of the lowest position during the parallel squat A)
weightlifter B) powerlifter Measured angles are indicated the horizontal line indicates
the position of the thigh
DISCUSSION
Since squatting exercise is an important part of the strength training for many athletes
it is important to understand the effects of different squatting techniques In this study we
used weightlifters and powerlifters to demonstrate effects of the high- and low-bar squats
We are aware that there is a difference in age between the two lifter categories but the
analysis showed no difference in principle muscular activity or load between the oldest and
youngest lifters in each group
The study shows the differences between the high- and low-bar techniques and also the
effects on the hip and knee moment of force The low-bar squat with the barbell further
down on the back is characterized of a larger hip flexion (Fig 6) and this technique creates a
hip moment of force that in Newton-meter is almost twice as large as the knee moment The
high-bar squat however is performed more upright and the joint moment of force are more
equally distributed between the hip and knee joints The hip and knee angles in the present
study correlate well with the angles found by Fry et al (12) and confirm the more upright
position during the high-bar squat Although the powerlifters were larger and lifted heavier
loads than the weightlifters the mean moment of force on the knee joint was lower than for
the weightlifter and the difference was significant for the parallel squat The powerlifters
however had significantly a higher load on the hip joint compared with the weightlifters The
difference in hip load could be an effect of heavier lifters lifting heavier loads in addition to
an effect of different technique but the difference in knee moment of force could hardly be
explained from anything else but different lifting technique It is clear that weightlifter
coaches want the squat to be done as upright as possible This is the only way to approach the
movement during weightlifting competition Powerlifting coaches however want lifters to lift
as much as possible with hip and back since by experience they know that this enables the
lifter to lift heavier loads The calculated moment of force on the joint is dependent on the
size of the ground reaction force and the distance between this force and the joint center
the moment arm By increasing hip flexion the powerlifters manage to balance the weight
closer to the knee and thereby reduce the moment arm The moment arm between the
ground reaction force and the hip joint however will increase creating a higher moment of
force on this joint The high-bar squat is performed in a more balanced way where both the
barbell and the trunk center of gravity are centered between hip and knee and thereby the
moments of force are more equally distributed
The powerlifters showed higher EMG activity than the weightlifters for all investigated
muscles although the difference was significant only for the rectus femoris The powerlifters
were heavier and lifted heavier loads but this could be the explanation to the higher muscular
activity EMG activity however was normalized in relation to a reference contraction with
the same relative external load which might indicate that the low-bar squat actually is
advantageous from a muscular recruitment point of view It is clear however that
weightlifters must train with a technique close to the competition situation which means the
high-bar squat Some other athletes might benefit from using a technique close to the low-bar
squat providing that they have the low back strength to safely perform a low bar squat
It is a little surprising that powerlifters performing low-bar squats with relatively low
moment of force at the knee joints have a knee extensor muscular activity even slightly
higher than weightlifters performing high-bar squats with higher knee moments The
explanation must be that the moments calculated are net loading moments of force which
means that muscular co-contraction is not included in the values calculated The activity in the
biceps femoris muscle is slightly higher for the low-bar squat The activity in the
gastrocnemius muscle and the soleus muscle was not recorded However since the low-bar
squat is performed with the total center of gravity further forward the need for
compensatory ankle plantar flexion will increase which means increased activity in both the
gastrocnemius and the soleus muscles During the low-bar squat knee flexor muscle activity
increases and hereby knee extensor co-contraction This can explain why the knee extensor
activity is high despite the relatively low net knee loading moment As previously mentioned
one should be aware that the calculated moments are net moments of force and that the
effect of co-contracting antagonistic muscles are not taken into account A antagonistic
moment of force created by the antagonist would increase the moment of force produced by
the agonists Therefore the moment calculated in this study must be taken as minimum
loading moments for the agonists Two joint muscles can in this way serve as agonist at one
of the joints and antagonists at an other The biceps femoris for example produce an
extending moment of force at the hip but an antagonistic flexing moment of force at the
knee The magnitude of this antagonistic moment is not possible to calculate in a study like
this
Although hip extensor activity was not analyzed it seems logical that the low-bar squat
should be the best technique concerning hip extensor training since this technique create the
greatest moments of force at the joint
The patello-femoral compression force was calculated to give an apprehension of the
force magnitudes Forces in the hip and knee depend not only on the moment of force but
also on joint angle (222425) For a constant moment of force joint compression forces
increase with increasing flexion angle This has been investigated for hip flexion up to 90deg and
for knee flexion up to 120deg For the knee the patello-femoral compression force levels away
between 90 and 120deg So the reason for larger compression force in the knee for the
weightliftres was not because of a larger knee flexion angles rather related to the larger
moment of force
Both the weightlifters and powerlifters have a strict and precise squatting technique It is
probable that many other athletes in other disciplines use techniques in between the high- and
low-bar techniques and that their coaches are not aware of the effects of the different
techniques Athletes should benefit from studying lifters and their technique and the different
effects that can be achieved It is known that squatting exercise is a good method for knee
rehabilitation training (30) and we suggest that after a hip injury high-bar squat should be
used at the beginning to minimize the risk of hip overload After a knee injury a squatting
technique more similar to the low-bar technique should be preferred Further investigation
on for example shear and compression forces on the lumbar spine during the two different
types of squatting technique must be important to prevent reinjury of the lower back during
rehabilitation exercise
REFERENCES
1 Ariel B G Biomechanical analysis of the knee joint during deep knee bends with heavy
load In Biomechanics IV A J Nelson and C A Morehouse (Eds) Baltimore University
Park Press 1975 pp 44-52 [Context Link]
2 Baumann W V Gross K Quade P Galbierz and A Schwirtz The snatch technique of
world class weightlifters at the 1985 world championships Int J Sprots Biomech 468-89
1988 [Context Link]
3 Chandler T J and M H Stone The squat exercise in athletic conditioning a review of
the literature Natl Strength Condit Assoc J 1352-58 1991 [Context Link]
4 Coaches Roundtable The squat and its application to athletic performance Natl Strength
Condit Assoc J 610-22 1984 [Context Link]
5 Dahlkvist N J P Mayo and B B Seedhom Forces during squatting and rising from a
deep squat Eng Med 269-76 1982 [Context Link]
6 Dempster W T and G R L Gaughran Properties of body segments based on size and
weight Am J Anat 12033-54 1967 [Context Link]
7 Ekholm J R Nisell U P Arborelius C Hammarberg and G Nemeth Load on knee
joint structures and muscular activity during lifting Scand J Rehabil Med 161-9 1984
Bibliographic Links [Context Link]
8 Ekholm J R Nisell U P Arborelius O Svensson and G Nemeth Load on knee joint
and knee muscular activity during machine milking Ergonomics 4665-682 1985
Bibliographic Links [Context Link]
9 Ellis M I B B Seedhom A A Amis D Dowson and V Wright Forces in the knee joint
whilst rising from normal and motorized chairs Eng Med 133-40 1979 [Context Link]
10 Enoka R M The pull in Olympic weightliftingMed Sci Sports 2131-137 1979 [Context
Link]
11 Enoka R M Load- and skill-related changes in segmental contributions to a weightlifting
movement Med Sci Sports Exerc 2178-187 1988 [Context Link]
12 Fry A C T A Aro J A Bauer and W J Kraemer A comparison of methods for
determining kinematic properties of three barbell squat exercises J Hum Mov Stud 2483-
95 1993 [Context Link]
13 Garhammer J Performance evaluation of Olympic weightlifters Med Sci Sports 3284-
287 1979 [Context Link]
14 Garhammer J Power production by olympic weightlifters Med Sci Sports Exerc 154-
60 1980 [Context Link]
15 Garhammer J Biomechanical profiles of olympic weightlifters Int J Sports Biomech
1122-130 1985 [Context Link]
16 Grenier R and A Guimont Simultaneous bilateral rupture of the quadriceps tendon and
leg fractures in a weightlifterAm J Sports Med 6451-453 1983 Bibliographic Links
[Context Link]
[Context Link]
17 Hammarskjoumlld E K Harms-Ringdahl and J Ekholm Shoulder-arm muscular activity and
reproducibility in carpenters work Clin Biomech 581-87 1990 Bibliographic Links
[Context Link]
18 Hattin H C M R Pierrynowski and K A Ball Effect of load cadence and fatigue on
tibio-femoral joint force during a half squat Med Sci Sports Exerc 5613-618 1989
[Context Link]
19 Lander J F R L Simonton and J K F Giacobbe The effectiveness of weight-belts
during the squat exercise Med Sci Sports Exerc 22117-126 1990 Ovid Full Text
Bibliographic Links [Context Link]
20 Lander J E J R Hundley and R L Simonton The effectiveness of weight-belts
during multiple repetitions of the squat exercise Med Sci Sports Exerc 24603-609 1992
Ovid Full Text Bibliographic Links [Context Link]
21 Lindbeck L and U P Arborelius Inertial effects from single body segments in dynamic
analysis of lifting Ergonomics 4421-433 1991 Bibliographic Links [Context Link]
22 McLaughlin T M C J Dillman and T J Lardner A kinematic model of performance in
the parallel squat by champion powerliftersMed Sci Sports 2128-133 1977 [Context Link]
23 McLaughlin T M T J Lardner and C J Dillman Kinetics of the parallel squat Res Q
2175-189 1978 [Context Link]
24 Nemeth G and J Ekholm A biomechanical analysis of hip compression loading during
lifting Ergonomics 28429-440 1985 Bibliographic Links [Context Link]
25 Nemeth G J Ekholm and U P Arborelius Hip load moments and muscular activity
during lifting Scand J Rehabil Med 16103-111 1984 Bibliographic Links [Context Link]
26 Nemeth G J Ekholm U P Arborelius K Schlt951gtuldt and K Harms-Ringdahl Hip
joint load and muscular activation during rising exercises Scand J Rehabil Med 1693-102
1984 Bibliographic Links [Context Link]
27 Nisell R and J Ekholm Patellar forces during knee extension Scand J Rehabil Med
1763-74 1985 Bibliographic Links [Context Link]
28 Nisell R and J Ekholm Joint load during the parallel squat in powerlifting and forces of
in vivo bilateral quadriceps tendon rupture Scand J Sports Sci 863-70 1986 [Context
Link]
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Select All Export Selected to PowerPoint
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Link]
30 Palmitier R A K-N An S G Scott and E Y S Chao Kinetic chain exercise in knee
rehabilitation Sports Med 11402-413 1991 Ovid Full Text Bibliographic Links [Context
Link]
31 Weidenhielm L Knee osteoarthrosis aspects of clinical symptoms corrective surgery leg
alignment and knee joint load(Dissertation) Karolinska Institute Stockholm Sweden 1992
[Context Link]
32 Wretenberg P F Yi F Lindberg and U P Arborelius Joint moment of force and
quadriceps muscle activity during squatting exercise Scand J Med Sci Sports 3244-250
1993 Bibliographic Links [Context Link]
33 Zernicke R F J Garhammer and F W Jobe Human patellar-tendon rupture J
Bone Joint Surg Am A-59179-183 1977 [Context Link]
WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
IMAGE GALLERY
Table 1
Figure 1-Weightlifte
Figure 2-Calculation
Figure 3-Individual
Figure 4-Mean maximu
Figure 5-Mean maximu
Figure 6-Schematic d
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piezoelectric platform (type 9281 B) which measured the vertical anteroposterior and
lateral ground reaction forces during rising All force signals (sampled at 100 Hz) were
channelled through Kistler amplifying units (type 5006) to a microcomputer (Luxor ABC 800)
where they were AD converted and stored The position of the center of pressure of the
reaction force between the feet and the ground was also obtained from the force plate
Combining these data with the video coordinates gave the appropriate sagittal moment arms
with respect to the hip and knee joint markers Dempsters anthropometrical data (6) were
used to determine the segmental masses and their mass center locations
A computer program based on free-body mechanics was designed to calculate the
moments of force about the hip (superior part of greater trochanter) and knee (center of
lateral epicondyle) by multiplying each external force (body segment weight or horizontal or
vertical reaction force) by its moment arm length (Fig 2) A ldquosemidynamicrdquo method was
used which incorporated ground reaction forces measured from a force plate and
gravitational contributions from body segments Semidynamic methods have proved to give
results very close to calculation with fully dynamic methods (21) McLaughlin et al (23) and
Lander et al (19) have also analyzed torques and joint forces for squat movements with both
dynamic and semidynamic methods and they found only minor differences indicating that
this kind of method is adequate for these calculations These studies show that the inertial
forces are low compared with the ground reaction forces Similar methods for calculation of
moment of force have been used earlier (5926) and this particular system has been used in
several investigations (eg 31) The same type of technique has also been used in similar
weightlifting studies (210) but fully dynamic methods also are used in weightlifting studies
(11) The patellofemoral compressive force during the parallel squat was calculated using our
moment of force data and diagrams previously published by Nisell and Ekholm (27)
Figure 2-Calculation of the moment of force about the hip(MH) RX and RY are the
horizontal and vertical components of the reaction force from the force plate WT WS
and WF are the segmental weights of thigh shank and foot (XH YH) are the X and Y
cordinates for the marker on the hip joint(XT YT) (XS YS) and (XF YF) are the X and
Y coordinates for the center of gravity of the thigh shank and foot XR and YR are the X
and Y coordinates of the application point of the reaction force
The activity in the vastus lateralis rectus femoris and the long head of the biceps
femoris muscles was recorded (Devices M4 AC8) by means of full-wave rectified low-pass-
filtered and time-averaged electromyogram (linear envelope EMG) The low-pass time
constant was 100 ms Surface (AgAgCl) electrodes were placed on the skin over the muscles
in the fibers direction with an inter-electrode distance of 2 cm For control of artifacts
direct EMG was visualized in parallel on an oscilloscope (Tektronix RM565)
To quantify the muscular activity and to compare the activity between different squats
the EMG activity during the movements was related to a static reference action As reference
contraction a parallel squat with a barbell weight of 65 of 1 RM was chosen The peak EMG
value during a 3-s static parallel position was used as the reference value The muscular
activity is expressed as a quotient of the reference value Normalization like this has been
used earlier (7817)
Statistics
Since the data were approximately normally distributed and since this type of data in
general is known to be normally distributed the parametrict test was used for the statistical
analysis Comparison was done between parallel and deep squats within each group and
between powerlifters and weightlifters for the parallel and deep squat respectively For the
comparison between weightlifters and powerlifters one has to be aware of the differences in
groups concerning body weights and lifted weights
RESULTS
Moments of Force
The joint moment of force curves for one weightlifter and one powerlifter are shown in
Figure 3 All flexing loading moments of force are expressed as positive which means that
the curves describe mainly flexing loading moments for both the hip and the knee These
flexing moments are counteracted by the extensor muscles producing extending moments on
the hip and knee joints The calculated moments are the net muscular moments the effects
of antagonistic muscular activity are not considered The distinct peaks on the curves
correspond to the turning point during the change from knee flexion to knee extension The
two lifters have different load distributions The powerlifter put relatively more load on the
hip joint than on the knee joint while the weightlifter had a more equal distribution of load
between hip and knee
Figure 3-Individual moment curves for one weightlifter and one powerlifter performing a
deep squat Flexing loading moment of force are expressed as positive
Figure 4 shows the mean maximum moments of force for the hip and knee joints for the
different lifters during both the parallel squat and the deep squat Also the mean moment
data show that the weightlifters have a more equal load distribution between hip and knee
than the powerlifters The mean maximum moment at the hip joint was for the powerlifters
324 Nm (deep) and 309 Nm (parallel) The corresponding values for the weightlifters were 230
Nm (deep) and 216 Nm (parallel) The powerlifters had a significantly higher hip moment of
force both for the parallel and deep squat (P lt 005) The differences between the parallel
and the deep squats within each group were not significant At the knee joint there was a
different situation Although the powerlifters were heavier and lifted heavier loads than the
weightlifters they showed the lowest moment of force both for the parallel and the deep
squats and the difference was significant(P lt 005) for the parallel squat The mean
maximum moments were for the powerlifters 139 Nm (deep) and 92 Nm (parallel) For the
weightlifters the mean maximum flexing knee moments were 191 Nm (deep) and 131 Nm
(parallel) Independent of technique the load on the knees increased significantly with
increasing squatting depth (P lt 0005)
Figure 4-Mean maximum moment of force with 95 confidence interval on the hip and
knee joints for the weightlifters and powerlifters during parallel squat and deep squat
(WE N = 8 PON = 6)
The weightlifters showed positive correlation between hip load and the total mass of lifter
and barbell The strongest correlation was found for the deep squat (r = 092) but the
correlation was also significant for the parallel squat (r = 088 P lt 001) There was also a
tendency to positive correlation between hip load and total mass for the powerlifters both for
the parallel (r = 075) and the deep (r = 076) squat but with only six lifters the correlation
was not significant The corresponding values for the knee joint showed that the moments of
force did not increase proportionally with external load This has been found earlier for world
class weightlifters (2)
Knee Forces
We thought it would be interesting to calculate one force component in the knee that
would reflect the magnitudes of the forces in the knee during squatting Therefore the
patello-femoral compression force for the parallel squat was calculated The mean peak
compression force for the weightlifters was 4700 N (SD plusmn 590) and for the powerlifters 3300 N
(SD plusmn 1700) (26)
Electromyography
The muscular activity in the vastus lateralis the rectus femoris and the biceps femoris
muscles was recorded and the mean muscular activity peaks with 95 confidence intervals
are shown in Figure 5 For all muscles and both the parallel and the deep squat the mean peak
muscular activity was higher for the powerlifters However in this study with six powerlifters
and eight weightlifters a significant difference was found only for the rectus femoris muscle
(P lt 005) The highest activity levels both for the weightlifters and the powerlifters were
found for the biceps femoris muscle with a relative muscular activity of about three times
the reference level However the activity in this muscle also showed the greatest individual
difference
Figure 5-Mean maximum muscular activity for the three muscles studied with 95
confidence interval 10 corresponds to the activity during the static reference
contraction (WE N = 8 PON = 6)
Movement and Joint Angles
The knee flexion angles were slightly smaller for the powerlifters The mean knee flexion
angle for the powerlifters were 111deg (SD plusmn 5) for the parallel and 126deg (SD plusmn 4) for the deep
squat The corresponding angles for the weightlifters was 116deg (SD plusmn 5) for the parallel and
138deg (SD plusmn 3) for the deep squat Analyses of the hip flexion angles show that both the
weightlifters and the powerlifters increased these angles with increasing squating depth The
mean maximal hip flexion angles for the weightlifters was 111deg (SD plusmn 8) during the parallel
squat and 125deg (SD plusmn 4) during the deep squat The corresponding angles for the power lifters
were 132deg (SD plusmn 4) and 146deg (SD plusmn 3) respectively By flexing the hip more the powerlifters
leaned the trunk farther forward (Fig 6)
Figure 6-Schematic drawing of the lowest position during the parallel squat A)
weightlifter B) powerlifter Measured angles are indicated the horizontal line indicates
the position of the thigh
DISCUSSION
Since squatting exercise is an important part of the strength training for many athletes
it is important to understand the effects of different squatting techniques In this study we
used weightlifters and powerlifters to demonstrate effects of the high- and low-bar squats
We are aware that there is a difference in age between the two lifter categories but the
analysis showed no difference in principle muscular activity or load between the oldest and
youngest lifters in each group
The study shows the differences between the high- and low-bar techniques and also the
effects on the hip and knee moment of force The low-bar squat with the barbell further
down on the back is characterized of a larger hip flexion (Fig 6) and this technique creates a
hip moment of force that in Newton-meter is almost twice as large as the knee moment The
high-bar squat however is performed more upright and the joint moment of force are more
equally distributed between the hip and knee joints The hip and knee angles in the present
study correlate well with the angles found by Fry et al (12) and confirm the more upright
position during the high-bar squat Although the powerlifters were larger and lifted heavier
loads than the weightlifters the mean moment of force on the knee joint was lower than for
the weightlifter and the difference was significant for the parallel squat The powerlifters
however had significantly a higher load on the hip joint compared with the weightlifters The
difference in hip load could be an effect of heavier lifters lifting heavier loads in addition to
an effect of different technique but the difference in knee moment of force could hardly be
explained from anything else but different lifting technique It is clear that weightlifter
coaches want the squat to be done as upright as possible This is the only way to approach the
movement during weightlifting competition Powerlifting coaches however want lifters to lift
as much as possible with hip and back since by experience they know that this enables the
lifter to lift heavier loads The calculated moment of force on the joint is dependent on the
size of the ground reaction force and the distance between this force and the joint center
the moment arm By increasing hip flexion the powerlifters manage to balance the weight
closer to the knee and thereby reduce the moment arm The moment arm between the
ground reaction force and the hip joint however will increase creating a higher moment of
force on this joint The high-bar squat is performed in a more balanced way where both the
barbell and the trunk center of gravity are centered between hip and knee and thereby the
moments of force are more equally distributed
The powerlifters showed higher EMG activity than the weightlifters for all investigated
muscles although the difference was significant only for the rectus femoris The powerlifters
were heavier and lifted heavier loads but this could be the explanation to the higher muscular
activity EMG activity however was normalized in relation to a reference contraction with
the same relative external load which might indicate that the low-bar squat actually is
advantageous from a muscular recruitment point of view It is clear however that
weightlifters must train with a technique close to the competition situation which means the
high-bar squat Some other athletes might benefit from using a technique close to the low-bar
squat providing that they have the low back strength to safely perform a low bar squat
It is a little surprising that powerlifters performing low-bar squats with relatively low
moment of force at the knee joints have a knee extensor muscular activity even slightly
higher than weightlifters performing high-bar squats with higher knee moments The
explanation must be that the moments calculated are net loading moments of force which
means that muscular co-contraction is not included in the values calculated The activity in the
biceps femoris muscle is slightly higher for the low-bar squat The activity in the
gastrocnemius muscle and the soleus muscle was not recorded However since the low-bar
squat is performed with the total center of gravity further forward the need for
compensatory ankle plantar flexion will increase which means increased activity in both the
gastrocnemius and the soleus muscles During the low-bar squat knee flexor muscle activity
increases and hereby knee extensor co-contraction This can explain why the knee extensor
activity is high despite the relatively low net knee loading moment As previously mentioned
one should be aware that the calculated moments are net moments of force and that the
effect of co-contracting antagonistic muscles are not taken into account A antagonistic
moment of force created by the antagonist would increase the moment of force produced by
the agonists Therefore the moment calculated in this study must be taken as minimum
loading moments for the agonists Two joint muscles can in this way serve as agonist at one
of the joints and antagonists at an other The biceps femoris for example produce an
extending moment of force at the hip but an antagonistic flexing moment of force at the
knee The magnitude of this antagonistic moment is not possible to calculate in a study like
this
Although hip extensor activity was not analyzed it seems logical that the low-bar squat
should be the best technique concerning hip extensor training since this technique create the
greatest moments of force at the joint
The patello-femoral compression force was calculated to give an apprehension of the
force magnitudes Forces in the hip and knee depend not only on the moment of force but
also on joint angle (222425) For a constant moment of force joint compression forces
increase with increasing flexion angle This has been investigated for hip flexion up to 90deg and
for knee flexion up to 120deg For the knee the patello-femoral compression force levels away
between 90 and 120deg So the reason for larger compression force in the knee for the
weightliftres was not because of a larger knee flexion angles rather related to the larger
moment of force
Both the weightlifters and powerlifters have a strict and precise squatting technique It is
probable that many other athletes in other disciplines use techniques in between the high- and
low-bar techniques and that their coaches are not aware of the effects of the different
techniques Athletes should benefit from studying lifters and their technique and the different
effects that can be achieved It is known that squatting exercise is a good method for knee
rehabilitation training (30) and we suggest that after a hip injury high-bar squat should be
used at the beginning to minimize the risk of hip overload After a knee injury a squatting
technique more similar to the low-bar technique should be preferred Further investigation
on for example shear and compression forces on the lumbar spine during the two different
types of squatting technique must be important to prevent reinjury of the lower back during
rehabilitation exercise
REFERENCES
1 Ariel B G Biomechanical analysis of the knee joint during deep knee bends with heavy
load In Biomechanics IV A J Nelson and C A Morehouse (Eds) Baltimore University
Park Press 1975 pp 44-52 [Context Link]
2 Baumann W V Gross K Quade P Galbierz and A Schwirtz The snatch technique of
world class weightlifters at the 1985 world championships Int J Sprots Biomech 468-89
1988 [Context Link]
3 Chandler T J and M H Stone The squat exercise in athletic conditioning a review of
the literature Natl Strength Condit Assoc J 1352-58 1991 [Context Link]
4 Coaches Roundtable The squat and its application to athletic performance Natl Strength
Condit Assoc J 610-22 1984 [Context Link]
5 Dahlkvist N J P Mayo and B B Seedhom Forces during squatting and rising from a
deep squat Eng Med 269-76 1982 [Context Link]
6 Dempster W T and G R L Gaughran Properties of body segments based on size and
weight Am J Anat 12033-54 1967 [Context Link]
7 Ekholm J R Nisell U P Arborelius C Hammarberg and G Nemeth Load on knee
joint structures and muscular activity during lifting Scand J Rehabil Med 161-9 1984
Bibliographic Links [Context Link]
8 Ekholm J R Nisell U P Arborelius O Svensson and G Nemeth Load on knee joint
and knee muscular activity during machine milking Ergonomics 4665-682 1985
Bibliographic Links [Context Link]
9 Ellis M I B B Seedhom A A Amis D Dowson and V Wright Forces in the knee joint
whilst rising from normal and motorized chairs Eng Med 133-40 1979 [Context Link]
10 Enoka R M The pull in Olympic weightliftingMed Sci Sports 2131-137 1979 [Context
Link]
11 Enoka R M Load- and skill-related changes in segmental contributions to a weightlifting
movement Med Sci Sports Exerc 2178-187 1988 [Context Link]
12 Fry A C T A Aro J A Bauer and W J Kraemer A comparison of methods for
determining kinematic properties of three barbell squat exercises J Hum Mov Stud 2483-
95 1993 [Context Link]
13 Garhammer J Performance evaluation of Olympic weightlifters Med Sci Sports 3284-
287 1979 [Context Link]
14 Garhammer J Power production by olympic weightlifters Med Sci Sports Exerc 154-
60 1980 [Context Link]
15 Garhammer J Biomechanical profiles of olympic weightlifters Int J Sports Biomech
1122-130 1985 [Context Link]
16 Grenier R and A Guimont Simultaneous bilateral rupture of the quadriceps tendon and
leg fractures in a weightlifterAm J Sports Med 6451-453 1983 Bibliographic Links
[Context Link]
[Context Link]
17 Hammarskjoumlld E K Harms-Ringdahl and J Ekholm Shoulder-arm muscular activity and
reproducibility in carpenters work Clin Biomech 581-87 1990 Bibliographic Links
[Context Link]
18 Hattin H C M R Pierrynowski and K A Ball Effect of load cadence and fatigue on
tibio-femoral joint force during a half squat Med Sci Sports Exerc 5613-618 1989
[Context Link]
19 Lander J F R L Simonton and J K F Giacobbe The effectiveness of weight-belts
during the squat exercise Med Sci Sports Exerc 22117-126 1990 Ovid Full Text
Bibliographic Links [Context Link]
20 Lander J E J R Hundley and R L Simonton The effectiveness of weight-belts
during multiple repetitions of the squat exercise Med Sci Sports Exerc 24603-609 1992
Ovid Full Text Bibliographic Links [Context Link]
21 Lindbeck L and U P Arborelius Inertial effects from single body segments in dynamic
analysis of lifting Ergonomics 4421-433 1991 Bibliographic Links [Context Link]
22 McLaughlin T M C J Dillman and T J Lardner A kinematic model of performance in
the parallel squat by champion powerliftersMed Sci Sports 2128-133 1977 [Context Link]
23 McLaughlin T M T J Lardner and C J Dillman Kinetics of the parallel squat Res Q
2175-189 1978 [Context Link]
24 Nemeth G and J Ekholm A biomechanical analysis of hip compression loading during
lifting Ergonomics 28429-440 1985 Bibliographic Links [Context Link]
25 Nemeth G J Ekholm and U P Arborelius Hip load moments and muscular activity
during lifting Scand J Rehabil Med 16103-111 1984 Bibliographic Links [Context Link]
26 Nemeth G J Ekholm U P Arborelius K Schlt951gtuldt and K Harms-Ringdahl Hip
joint load and muscular activation during rising exercises Scand J Rehabil Med 1693-102
1984 Bibliographic Links [Context Link]
27 Nisell R and J Ekholm Patellar forces during knee extension Scand J Rehabil Med
1763-74 1985 Bibliographic Links [Context Link]
28 Nisell R and J Ekholm Joint load during the parallel squat in powerlifting and forces of
in vivo bilateral quadriceps tendon rupture Scand J Sports Sci 863-70 1986 [Context
Link]
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Select All Export Selected to PowerPoint
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Link]
30 Palmitier R A K-N An S G Scott and E Y S Chao Kinetic chain exercise in knee
rehabilitation Sports Med 11402-413 1991 Ovid Full Text Bibliographic Links [Context
Link]
31 Weidenhielm L Knee osteoarthrosis aspects of clinical symptoms corrective surgery leg
alignment and knee joint load(Dissertation) Karolinska Institute Stockholm Sweden 1992
[Context Link]
32 Wretenberg P F Yi F Lindberg and U P Arborelius Joint moment of force and
quadriceps muscle activity during squatting exercise Scand J Med Sci Sports 3244-250
1993 Bibliographic Links [Context Link]
33 Zernicke R F J Garhammer and F W Jobe Human patellar-tendon rupture J
Bone Joint Surg Am A-59179-183 1977 [Context Link]
WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
IMAGE GALLERY
Table 1
Figure 1-Weightlifte
Figure 2-Calculation
Figure 3-Individual
Figure 4-Mean maximu
Figure 5-Mean maximu
Figure 6-Schematic d
Back to Top
Copyright (c) 2000-2014 Ovid Technologies Inc
Terms of Use Support amp Training About Us Contact Us
Version OvidSP_UI031200116 SourceID 60384
To quantify the muscular activity and to compare the activity between different squats
the EMG activity during the movements was related to a static reference action As reference
contraction a parallel squat with a barbell weight of 65 of 1 RM was chosen The peak EMG
value during a 3-s static parallel position was used as the reference value The muscular
activity is expressed as a quotient of the reference value Normalization like this has been
used earlier (7817)
Statistics
Since the data were approximately normally distributed and since this type of data in
general is known to be normally distributed the parametrict test was used for the statistical
analysis Comparison was done between parallel and deep squats within each group and
between powerlifters and weightlifters for the parallel and deep squat respectively For the
comparison between weightlifters and powerlifters one has to be aware of the differences in
groups concerning body weights and lifted weights
RESULTS
Moments of Force
The joint moment of force curves for one weightlifter and one powerlifter are shown in
Figure 3 All flexing loading moments of force are expressed as positive which means that
the curves describe mainly flexing loading moments for both the hip and the knee These
flexing moments are counteracted by the extensor muscles producing extending moments on
the hip and knee joints The calculated moments are the net muscular moments the effects
of antagonistic muscular activity are not considered The distinct peaks on the curves
correspond to the turning point during the change from knee flexion to knee extension The
two lifters have different load distributions The powerlifter put relatively more load on the
hip joint than on the knee joint while the weightlifter had a more equal distribution of load
between hip and knee
Figure 3-Individual moment curves for one weightlifter and one powerlifter performing a
deep squat Flexing loading moment of force are expressed as positive
Figure 4 shows the mean maximum moments of force for the hip and knee joints for the
different lifters during both the parallel squat and the deep squat Also the mean moment
data show that the weightlifters have a more equal load distribution between hip and knee
than the powerlifters The mean maximum moment at the hip joint was for the powerlifters
324 Nm (deep) and 309 Nm (parallel) The corresponding values for the weightlifters were 230
Nm (deep) and 216 Nm (parallel) The powerlifters had a significantly higher hip moment of
force both for the parallel and deep squat (P lt 005) The differences between the parallel
and the deep squats within each group were not significant At the knee joint there was a
different situation Although the powerlifters were heavier and lifted heavier loads than the
weightlifters they showed the lowest moment of force both for the parallel and the deep
squats and the difference was significant(P lt 005) for the parallel squat The mean
maximum moments were for the powerlifters 139 Nm (deep) and 92 Nm (parallel) For the
weightlifters the mean maximum flexing knee moments were 191 Nm (deep) and 131 Nm
(parallel) Independent of technique the load on the knees increased significantly with
increasing squatting depth (P lt 0005)
Figure 4-Mean maximum moment of force with 95 confidence interval on the hip and
knee joints for the weightlifters and powerlifters during parallel squat and deep squat
(WE N = 8 PON = 6)
The weightlifters showed positive correlation between hip load and the total mass of lifter
and barbell The strongest correlation was found for the deep squat (r = 092) but the
correlation was also significant for the parallel squat (r = 088 P lt 001) There was also a
tendency to positive correlation between hip load and total mass for the powerlifters both for
the parallel (r = 075) and the deep (r = 076) squat but with only six lifters the correlation
was not significant The corresponding values for the knee joint showed that the moments of
force did not increase proportionally with external load This has been found earlier for world
class weightlifters (2)
Knee Forces
We thought it would be interesting to calculate one force component in the knee that
would reflect the magnitudes of the forces in the knee during squatting Therefore the
patello-femoral compression force for the parallel squat was calculated The mean peak
compression force for the weightlifters was 4700 N (SD plusmn 590) and for the powerlifters 3300 N
(SD plusmn 1700) (26)
Electromyography
The muscular activity in the vastus lateralis the rectus femoris and the biceps femoris
muscles was recorded and the mean muscular activity peaks with 95 confidence intervals
are shown in Figure 5 For all muscles and both the parallel and the deep squat the mean peak
muscular activity was higher for the powerlifters However in this study with six powerlifters
and eight weightlifters a significant difference was found only for the rectus femoris muscle
(P lt 005) The highest activity levels both for the weightlifters and the powerlifters were
found for the biceps femoris muscle with a relative muscular activity of about three times
the reference level However the activity in this muscle also showed the greatest individual
difference
Figure 5-Mean maximum muscular activity for the three muscles studied with 95
confidence interval 10 corresponds to the activity during the static reference
contraction (WE N = 8 PON = 6)
Movement and Joint Angles
The knee flexion angles were slightly smaller for the powerlifters The mean knee flexion
angle for the powerlifters were 111deg (SD plusmn 5) for the parallel and 126deg (SD plusmn 4) for the deep
squat The corresponding angles for the weightlifters was 116deg (SD plusmn 5) for the parallel and
138deg (SD plusmn 3) for the deep squat Analyses of the hip flexion angles show that both the
weightlifters and the powerlifters increased these angles with increasing squating depth The
mean maximal hip flexion angles for the weightlifters was 111deg (SD plusmn 8) during the parallel
squat and 125deg (SD plusmn 4) during the deep squat The corresponding angles for the power lifters
were 132deg (SD plusmn 4) and 146deg (SD plusmn 3) respectively By flexing the hip more the powerlifters
leaned the trunk farther forward (Fig 6)
Figure 6-Schematic drawing of the lowest position during the parallel squat A)
weightlifter B) powerlifter Measured angles are indicated the horizontal line indicates
the position of the thigh
DISCUSSION
Since squatting exercise is an important part of the strength training for many athletes
it is important to understand the effects of different squatting techniques In this study we
used weightlifters and powerlifters to demonstrate effects of the high- and low-bar squats
We are aware that there is a difference in age between the two lifter categories but the
analysis showed no difference in principle muscular activity or load between the oldest and
youngest lifters in each group
The study shows the differences between the high- and low-bar techniques and also the
effects on the hip and knee moment of force The low-bar squat with the barbell further
down on the back is characterized of a larger hip flexion (Fig 6) and this technique creates a
hip moment of force that in Newton-meter is almost twice as large as the knee moment The
high-bar squat however is performed more upright and the joint moment of force are more
equally distributed between the hip and knee joints The hip and knee angles in the present
study correlate well with the angles found by Fry et al (12) and confirm the more upright
position during the high-bar squat Although the powerlifters were larger and lifted heavier
loads than the weightlifters the mean moment of force on the knee joint was lower than for
the weightlifter and the difference was significant for the parallel squat The powerlifters
however had significantly a higher load on the hip joint compared with the weightlifters The
difference in hip load could be an effect of heavier lifters lifting heavier loads in addition to
an effect of different technique but the difference in knee moment of force could hardly be
explained from anything else but different lifting technique It is clear that weightlifter
coaches want the squat to be done as upright as possible This is the only way to approach the
movement during weightlifting competition Powerlifting coaches however want lifters to lift
as much as possible with hip and back since by experience they know that this enables the
lifter to lift heavier loads The calculated moment of force on the joint is dependent on the
size of the ground reaction force and the distance between this force and the joint center
the moment arm By increasing hip flexion the powerlifters manage to balance the weight
closer to the knee and thereby reduce the moment arm The moment arm between the
ground reaction force and the hip joint however will increase creating a higher moment of
force on this joint The high-bar squat is performed in a more balanced way where both the
barbell and the trunk center of gravity are centered between hip and knee and thereby the
moments of force are more equally distributed
The powerlifters showed higher EMG activity than the weightlifters for all investigated
muscles although the difference was significant only for the rectus femoris The powerlifters
were heavier and lifted heavier loads but this could be the explanation to the higher muscular
activity EMG activity however was normalized in relation to a reference contraction with
the same relative external load which might indicate that the low-bar squat actually is
advantageous from a muscular recruitment point of view It is clear however that
weightlifters must train with a technique close to the competition situation which means the
high-bar squat Some other athletes might benefit from using a technique close to the low-bar
squat providing that they have the low back strength to safely perform a low bar squat
It is a little surprising that powerlifters performing low-bar squats with relatively low
moment of force at the knee joints have a knee extensor muscular activity even slightly
higher than weightlifters performing high-bar squats with higher knee moments The
explanation must be that the moments calculated are net loading moments of force which
means that muscular co-contraction is not included in the values calculated The activity in the
biceps femoris muscle is slightly higher for the low-bar squat The activity in the
gastrocnemius muscle and the soleus muscle was not recorded However since the low-bar
squat is performed with the total center of gravity further forward the need for
compensatory ankle plantar flexion will increase which means increased activity in both the
gastrocnemius and the soleus muscles During the low-bar squat knee flexor muscle activity
increases and hereby knee extensor co-contraction This can explain why the knee extensor
activity is high despite the relatively low net knee loading moment As previously mentioned
one should be aware that the calculated moments are net moments of force and that the
effect of co-contracting antagonistic muscles are not taken into account A antagonistic
moment of force created by the antagonist would increase the moment of force produced by
the agonists Therefore the moment calculated in this study must be taken as minimum
loading moments for the agonists Two joint muscles can in this way serve as agonist at one
of the joints and antagonists at an other The biceps femoris for example produce an
extending moment of force at the hip but an antagonistic flexing moment of force at the
knee The magnitude of this antagonistic moment is not possible to calculate in a study like
this
Although hip extensor activity was not analyzed it seems logical that the low-bar squat
should be the best technique concerning hip extensor training since this technique create the
greatest moments of force at the joint
The patello-femoral compression force was calculated to give an apprehension of the
force magnitudes Forces in the hip and knee depend not only on the moment of force but
also on joint angle (222425) For a constant moment of force joint compression forces
increase with increasing flexion angle This has been investigated for hip flexion up to 90deg and
for knee flexion up to 120deg For the knee the patello-femoral compression force levels away
between 90 and 120deg So the reason for larger compression force in the knee for the
weightliftres was not because of a larger knee flexion angles rather related to the larger
moment of force
Both the weightlifters and powerlifters have a strict and precise squatting technique It is
probable that many other athletes in other disciplines use techniques in between the high- and
low-bar techniques and that their coaches are not aware of the effects of the different
techniques Athletes should benefit from studying lifters and their technique and the different
effects that can be achieved It is known that squatting exercise is a good method for knee
rehabilitation training (30) and we suggest that after a hip injury high-bar squat should be
used at the beginning to minimize the risk of hip overload After a knee injury a squatting
technique more similar to the low-bar technique should be preferred Further investigation
on for example shear and compression forces on the lumbar spine during the two different
types of squatting technique must be important to prevent reinjury of the lower back during
rehabilitation exercise
REFERENCES
1 Ariel B G Biomechanical analysis of the knee joint during deep knee bends with heavy
load In Biomechanics IV A J Nelson and C A Morehouse (Eds) Baltimore University
Park Press 1975 pp 44-52 [Context Link]
2 Baumann W V Gross K Quade P Galbierz and A Schwirtz The snatch technique of
world class weightlifters at the 1985 world championships Int J Sprots Biomech 468-89
1988 [Context Link]
3 Chandler T J and M H Stone The squat exercise in athletic conditioning a review of
the literature Natl Strength Condit Assoc J 1352-58 1991 [Context Link]
4 Coaches Roundtable The squat and its application to athletic performance Natl Strength
Condit Assoc J 610-22 1984 [Context Link]
5 Dahlkvist N J P Mayo and B B Seedhom Forces during squatting and rising from a
deep squat Eng Med 269-76 1982 [Context Link]
6 Dempster W T and G R L Gaughran Properties of body segments based on size and
weight Am J Anat 12033-54 1967 [Context Link]
7 Ekholm J R Nisell U P Arborelius C Hammarberg and G Nemeth Load on knee
joint structures and muscular activity during lifting Scand J Rehabil Med 161-9 1984
Bibliographic Links [Context Link]
8 Ekholm J R Nisell U P Arborelius O Svensson and G Nemeth Load on knee joint
and knee muscular activity during machine milking Ergonomics 4665-682 1985
Bibliographic Links [Context Link]
9 Ellis M I B B Seedhom A A Amis D Dowson and V Wright Forces in the knee joint
whilst rising from normal and motorized chairs Eng Med 133-40 1979 [Context Link]
10 Enoka R M The pull in Olympic weightliftingMed Sci Sports 2131-137 1979 [Context
Link]
11 Enoka R M Load- and skill-related changes in segmental contributions to a weightlifting
movement Med Sci Sports Exerc 2178-187 1988 [Context Link]
12 Fry A C T A Aro J A Bauer and W J Kraemer A comparison of methods for
determining kinematic properties of three barbell squat exercises J Hum Mov Stud 2483-
95 1993 [Context Link]
13 Garhammer J Performance evaluation of Olympic weightlifters Med Sci Sports 3284-
287 1979 [Context Link]
14 Garhammer J Power production by olympic weightlifters Med Sci Sports Exerc 154-
60 1980 [Context Link]
15 Garhammer J Biomechanical profiles of olympic weightlifters Int J Sports Biomech
1122-130 1985 [Context Link]
16 Grenier R and A Guimont Simultaneous bilateral rupture of the quadriceps tendon and
leg fractures in a weightlifterAm J Sports Med 6451-453 1983 Bibliographic Links
[Context Link]
[Context Link]
17 Hammarskjoumlld E K Harms-Ringdahl and J Ekholm Shoulder-arm muscular activity and
reproducibility in carpenters work Clin Biomech 581-87 1990 Bibliographic Links
[Context Link]
18 Hattin H C M R Pierrynowski and K A Ball Effect of load cadence and fatigue on
tibio-femoral joint force during a half squat Med Sci Sports Exerc 5613-618 1989
[Context Link]
19 Lander J F R L Simonton and J K F Giacobbe The effectiveness of weight-belts
during the squat exercise Med Sci Sports Exerc 22117-126 1990 Ovid Full Text
Bibliographic Links [Context Link]
20 Lander J E J R Hundley and R L Simonton The effectiveness of weight-belts
during multiple repetitions of the squat exercise Med Sci Sports Exerc 24603-609 1992
Ovid Full Text Bibliographic Links [Context Link]
21 Lindbeck L and U P Arborelius Inertial effects from single body segments in dynamic
analysis of lifting Ergonomics 4421-433 1991 Bibliographic Links [Context Link]
22 McLaughlin T M C J Dillman and T J Lardner A kinematic model of performance in
the parallel squat by champion powerliftersMed Sci Sports 2128-133 1977 [Context Link]
23 McLaughlin T M T J Lardner and C J Dillman Kinetics of the parallel squat Res Q
2175-189 1978 [Context Link]
24 Nemeth G and J Ekholm A biomechanical analysis of hip compression loading during
lifting Ergonomics 28429-440 1985 Bibliographic Links [Context Link]
25 Nemeth G J Ekholm and U P Arborelius Hip load moments and muscular activity
during lifting Scand J Rehabil Med 16103-111 1984 Bibliographic Links [Context Link]
26 Nemeth G J Ekholm U P Arborelius K Schlt951gtuldt and K Harms-Ringdahl Hip
joint load and muscular activation during rising exercises Scand J Rehabil Med 1693-102
1984 Bibliographic Links [Context Link]
27 Nisell R and J Ekholm Patellar forces during knee extension Scand J Rehabil Med
1763-74 1985 Bibliographic Links [Context Link]
28 Nisell R and J Ekholm Joint load during the parallel squat in powerlifting and forces of
in vivo bilateral quadriceps tendon rupture Scand J Sports Sci 863-70 1986 [Context
Link]
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Select All Export Selected to PowerPoint
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Link]
30 Palmitier R A K-N An S G Scott and E Y S Chao Kinetic chain exercise in knee
rehabilitation Sports Med 11402-413 1991 Ovid Full Text Bibliographic Links [Context
Link]
31 Weidenhielm L Knee osteoarthrosis aspects of clinical symptoms corrective surgery leg
alignment and knee joint load(Dissertation) Karolinska Institute Stockholm Sweden 1992
[Context Link]
32 Wretenberg P F Yi F Lindberg and U P Arborelius Joint moment of force and
quadriceps muscle activity during squatting exercise Scand J Med Sci Sports 3244-250
1993 Bibliographic Links [Context Link]
33 Zernicke R F J Garhammer and F W Jobe Human patellar-tendon rupture J
Bone Joint Surg Am A-59179-183 1977 [Context Link]
WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
IMAGE GALLERY
Table 1
Figure 1-Weightlifte
Figure 2-Calculation
Figure 3-Individual
Figure 4-Mean maximu
Figure 5-Mean maximu
Figure 6-Schematic d
Back to Top
Copyright (c) 2000-2014 Ovid Technologies Inc
Terms of Use Support amp Training About Us Contact Us
Version OvidSP_UI031200116 SourceID 60384
Figure 3-Individual moment curves for one weightlifter and one powerlifter performing a
deep squat Flexing loading moment of force are expressed as positive
Figure 4 shows the mean maximum moments of force for the hip and knee joints for the
different lifters during both the parallel squat and the deep squat Also the mean moment
data show that the weightlifters have a more equal load distribution between hip and knee
than the powerlifters The mean maximum moment at the hip joint was for the powerlifters
324 Nm (deep) and 309 Nm (parallel) The corresponding values for the weightlifters were 230
Nm (deep) and 216 Nm (parallel) The powerlifters had a significantly higher hip moment of
force both for the parallel and deep squat (P lt 005) The differences between the parallel
and the deep squats within each group were not significant At the knee joint there was a
different situation Although the powerlifters were heavier and lifted heavier loads than the
weightlifters they showed the lowest moment of force both for the parallel and the deep
squats and the difference was significant(P lt 005) for the parallel squat The mean
maximum moments were for the powerlifters 139 Nm (deep) and 92 Nm (parallel) For the
weightlifters the mean maximum flexing knee moments were 191 Nm (deep) and 131 Nm
(parallel) Independent of technique the load on the knees increased significantly with
increasing squatting depth (P lt 0005)
Figure 4-Mean maximum moment of force with 95 confidence interval on the hip and
knee joints for the weightlifters and powerlifters during parallel squat and deep squat
(WE N = 8 PON = 6)
The weightlifters showed positive correlation between hip load and the total mass of lifter
and barbell The strongest correlation was found for the deep squat (r = 092) but the
correlation was also significant for the parallel squat (r = 088 P lt 001) There was also a
tendency to positive correlation between hip load and total mass for the powerlifters both for
the parallel (r = 075) and the deep (r = 076) squat but with only six lifters the correlation
was not significant The corresponding values for the knee joint showed that the moments of
force did not increase proportionally with external load This has been found earlier for world
class weightlifters (2)
Knee Forces
We thought it would be interesting to calculate one force component in the knee that
would reflect the magnitudes of the forces in the knee during squatting Therefore the
patello-femoral compression force for the parallel squat was calculated The mean peak
compression force for the weightlifters was 4700 N (SD plusmn 590) and for the powerlifters 3300 N
(SD plusmn 1700) (26)
Electromyography
The muscular activity in the vastus lateralis the rectus femoris and the biceps femoris
muscles was recorded and the mean muscular activity peaks with 95 confidence intervals
are shown in Figure 5 For all muscles and both the parallel and the deep squat the mean peak
muscular activity was higher for the powerlifters However in this study with six powerlifters
and eight weightlifters a significant difference was found only for the rectus femoris muscle
(P lt 005) The highest activity levels both for the weightlifters and the powerlifters were
found for the biceps femoris muscle with a relative muscular activity of about three times
the reference level However the activity in this muscle also showed the greatest individual
difference
Figure 5-Mean maximum muscular activity for the three muscles studied with 95
confidence interval 10 corresponds to the activity during the static reference
contraction (WE N = 8 PON = 6)
Movement and Joint Angles
The knee flexion angles were slightly smaller for the powerlifters The mean knee flexion
angle for the powerlifters were 111deg (SD plusmn 5) for the parallel and 126deg (SD plusmn 4) for the deep
squat The corresponding angles for the weightlifters was 116deg (SD plusmn 5) for the parallel and
138deg (SD plusmn 3) for the deep squat Analyses of the hip flexion angles show that both the
weightlifters and the powerlifters increased these angles with increasing squating depth The
mean maximal hip flexion angles for the weightlifters was 111deg (SD plusmn 8) during the parallel
squat and 125deg (SD plusmn 4) during the deep squat The corresponding angles for the power lifters
were 132deg (SD plusmn 4) and 146deg (SD plusmn 3) respectively By flexing the hip more the powerlifters
leaned the trunk farther forward (Fig 6)
Figure 6-Schematic drawing of the lowest position during the parallel squat A)
weightlifter B) powerlifter Measured angles are indicated the horizontal line indicates
the position of the thigh
DISCUSSION
Since squatting exercise is an important part of the strength training for many athletes
it is important to understand the effects of different squatting techniques In this study we
used weightlifters and powerlifters to demonstrate effects of the high- and low-bar squats
We are aware that there is a difference in age between the two lifter categories but the
analysis showed no difference in principle muscular activity or load between the oldest and
youngest lifters in each group
The study shows the differences between the high- and low-bar techniques and also the
effects on the hip and knee moment of force The low-bar squat with the barbell further
down on the back is characterized of a larger hip flexion (Fig 6) and this technique creates a
hip moment of force that in Newton-meter is almost twice as large as the knee moment The
high-bar squat however is performed more upright and the joint moment of force are more
equally distributed between the hip and knee joints The hip and knee angles in the present
study correlate well with the angles found by Fry et al (12) and confirm the more upright
position during the high-bar squat Although the powerlifters were larger and lifted heavier
loads than the weightlifters the mean moment of force on the knee joint was lower than for
the weightlifter and the difference was significant for the parallel squat The powerlifters
however had significantly a higher load on the hip joint compared with the weightlifters The
difference in hip load could be an effect of heavier lifters lifting heavier loads in addition to
an effect of different technique but the difference in knee moment of force could hardly be
explained from anything else but different lifting technique It is clear that weightlifter
coaches want the squat to be done as upright as possible This is the only way to approach the
movement during weightlifting competition Powerlifting coaches however want lifters to lift
as much as possible with hip and back since by experience they know that this enables the
lifter to lift heavier loads The calculated moment of force on the joint is dependent on the
size of the ground reaction force and the distance between this force and the joint center
the moment arm By increasing hip flexion the powerlifters manage to balance the weight
closer to the knee and thereby reduce the moment arm The moment arm between the
ground reaction force and the hip joint however will increase creating a higher moment of
force on this joint The high-bar squat is performed in a more balanced way where both the
barbell and the trunk center of gravity are centered between hip and knee and thereby the
moments of force are more equally distributed
The powerlifters showed higher EMG activity than the weightlifters for all investigated
muscles although the difference was significant only for the rectus femoris The powerlifters
were heavier and lifted heavier loads but this could be the explanation to the higher muscular
activity EMG activity however was normalized in relation to a reference contraction with
the same relative external load which might indicate that the low-bar squat actually is
advantageous from a muscular recruitment point of view It is clear however that
weightlifters must train with a technique close to the competition situation which means the
high-bar squat Some other athletes might benefit from using a technique close to the low-bar
squat providing that they have the low back strength to safely perform a low bar squat
It is a little surprising that powerlifters performing low-bar squats with relatively low
moment of force at the knee joints have a knee extensor muscular activity even slightly
higher than weightlifters performing high-bar squats with higher knee moments The
explanation must be that the moments calculated are net loading moments of force which
means that muscular co-contraction is not included in the values calculated The activity in the
biceps femoris muscle is slightly higher for the low-bar squat The activity in the
gastrocnemius muscle and the soleus muscle was not recorded However since the low-bar
squat is performed with the total center of gravity further forward the need for
compensatory ankle plantar flexion will increase which means increased activity in both the
gastrocnemius and the soleus muscles During the low-bar squat knee flexor muscle activity
increases and hereby knee extensor co-contraction This can explain why the knee extensor
activity is high despite the relatively low net knee loading moment As previously mentioned
one should be aware that the calculated moments are net moments of force and that the
effect of co-contracting antagonistic muscles are not taken into account A antagonistic
moment of force created by the antagonist would increase the moment of force produced by
the agonists Therefore the moment calculated in this study must be taken as minimum
loading moments for the agonists Two joint muscles can in this way serve as agonist at one
of the joints and antagonists at an other The biceps femoris for example produce an
extending moment of force at the hip but an antagonistic flexing moment of force at the
knee The magnitude of this antagonistic moment is not possible to calculate in a study like
this
Although hip extensor activity was not analyzed it seems logical that the low-bar squat
should be the best technique concerning hip extensor training since this technique create the
greatest moments of force at the joint
The patello-femoral compression force was calculated to give an apprehension of the
force magnitudes Forces in the hip and knee depend not only on the moment of force but
also on joint angle (222425) For a constant moment of force joint compression forces
increase with increasing flexion angle This has been investigated for hip flexion up to 90deg and
for knee flexion up to 120deg For the knee the patello-femoral compression force levels away
between 90 and 120deg So the reason for larger compression force in the knee for the
weightliftres was not because of a larger knee flexion angles rather related to the larger
moment of force
Both the weightlifters and powerlifters have a strict and precise squatting technique It is
probable that many other athletes in other disciplines use techniques in between the high- and
low-bar techniques and that their coaches are not aware of the effects of the different
techniques Athletes should benefit from studying lifters and their technique and the different
effects that can be achieved It is known that squatting exercise is a good method for knee
rehabilitation training (30) and we suggest that after a hip injury high-bar squat should be
used at the beginning to minimize the risk of hip overload After a knee injury a squatting
technique more similar to the low-bar technique should be preferred Further investigation
on for example shear and compression forces on the lumbar spine during the two different
types of squatting technique must be important to prevent reinjury of the lower back during
rehabilitation exercise
REFERENCES
1 Ariel B G Biomechanical analysis of the knee joint during deep knee bends with heavy
load In Biomechanics IV A J Nelson and C A Morehouse (Eds) Baltimore University
Park Press 1975 pp 44-52 [Context Link]
2 Baumann W V Gross K Quade P Galbierz and A Schwirtz The snatch technique of
world class weightlifters at the 1985 world championships Int J Sprots Biomech 468-89
1988 [Context Link]
3 Chandler T J and M H Stone The squat exercise in athletic conditioning a review of
the literature Natl Strength Condit Assoc J 1352-58 1991 [Context Link]
4 Coaches Roundtable The squat and its application to athletic performance Natl Strength
Condit Assoc J 610-22 1984 [Context Link]
5 Dahlkvist N J P Mayo and B B Seedhom Forces during squatting and rising from a
deep squat Eng Med 269-76 1982 [Context Link]
6 Dempster W T and G R L Gaughran Properties of body segments based on size and
weight Am J Anat 12033-54 1967 [Context Link]
7 Ekholm J R Nisell U P Arborelius C Hammarberg and G Nemeth Load on knee
joint structures and muscular activity during lifting Scand J Rehabil Med 161-9 1984
Bibliographic Links [Context Link]
8 Ekholm J R Nisell U P Arborelius O Svensson and G Nemeth Load on knee joint
and knee muscular activity during machine milking Ergonomics 4665-682 1985
Bibliographic Links [Context Link]
9 Ellis M I B B Seedhom A A Amis D Dowson and V Wright Forces in the knee joint
whilst rising from normal and motorized chairs Eng Med 133-40 1979 [Context Link]
10 Enoka R M The pull in Olympic weightliftingMed Sci Sports 2131-137 1979 [Context
Link]
11 Enoka R M Load- and skill-related changes in segmental contributions to a weightlifting
movement Med Sci Sports Exerc 2178-187 1988 [Context Link]
12 Fry A C T A Aro J A Bauer and W J Kraemer A comparison of methods for
determining kinematic properties of three barbell squat exercises J Hum Mov Stud 2483-
95 1993 [Context Link]
13 Garhammer J Performance evaluation of Olympic weightlifters Med Sci Sports 3284-
287 1979 [Context Link]
14 Garhammer J Power production by olympic weightlifters Med Sci Sports Exerc 154-
60 1980 [Context Link]
15 Garhammer J Biomechanical profiles of olympic weightlifters Int J Sports Biomech
1122-130 1985 [Context Link]
16 Grenier R and A Guimont Simultaneous bilateral rupture of the quadriceps tendon and
leg fractures in a weightlifterAm J Sports Med 6451-453 1983 Bibliographic Links
[Context Link]
[Context Link]
17 Hammarskjoumlld E K Harms-Ringdahl and J Ekholm Shoulder-arm muscular activity and
reproducibility in carpenters work Clin Biomech 581-87 1990 Bibliographic Links
[Context Link]
18 Hattin H C M R Pierrynowski and K A Ball Effect of load cadence and fatigue on
tibio-femoral joint force during a half squat Med Sci Sports Exerc 5613-618 1989
[Context Link]
19 Lander J F R L Simonton and J K F Giacobbe The effectiveness of weight-belts
during the squat exercise Med Sci Sports Exerc 22117-126 1990 Ovid Full Text
Bibliographic Links [Context Link]
20 Lander J E J R Hundley and R L Simonton The effectiveness of weight-belts
during multiple repetitions of the squat exercise Med Sci Sports Exerc 24603-609 1992
Ovid Full Text Bibliographic Links [Context Link]
21 Lindbeck L and U P Arborelius Inertial effects from single body segments in dynamic
analysis of lifting Ergonomics 4421-433 1991 Bibliographic Links [Context Link]
22 McLaughlin T M C J Dillman and T J Lardner A kinematic model of performance in
the parallel squat by champion powerliftersMed Sci Sports 2128-133 1977 [Context Link]
23 McLaughlin T M T J Lardner and C J Dillman Kinetics of the parallel squat Res Q
2175-189 1978 [Context Link]
24 Nemeth G and J Ekholm A biomechanical analysis of hip compression loading during
lifting Ergonomics 28429-440 1985 Bibliographic Links [Context Link]
25 Nemeth G J Ekholm and U P Arborelius Hip load moments and muscular activity
during lifting Scand J Rehabil Med 16103-111 1984 Bibliographic Links [Context Link]
26 Nemeth G J Ekholm U P Arborelius K Schlt951gtuldt and K Harms-Ringdahl Hip
joint load and muscular activation during rising exercises Scand J Rehabil Med 1693-102
1984 Bibliographic Links [Context Link]
27 Nisell R and J Ekholm Patellar forces during knee extension Scand J Rehabil Med
1763-74 1985 Bibliographic Links [Context Link]
28 Nisell R and J Ekholm Joint load during the parallel squat in powerlifting and forces of
in vivo bilateral quadriceps tendon rupture Scand J Sports Sci 863-70 1986 [Context
Link]
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Select All Export Selected to PowerPoint
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Link]
30 Palmitier R A K-N An S G Scott and E Y S Chao Kinetic chain exercise in knee
rehabilitation Sports Med 11402-413 1991 Ovid Full Text Bibliographic Links [Context
Link]
31 Weidenhielm L Knee osteoarthrosis aspects of clinical symptoms corrective surgery leg
alignment and knee joint load(Dissertation) Karolinska Institute Stockholm Sweden 1992
[Context Link]
32 Wretenberg P F Yi F Lindberg and U P Arborelius Joint moment of force and
quadriceps muscle activity during squatting exercise Scand J Med Sci Sports 3244-250
1993 Bibliographic Links [Context Link]
33 Zernicke R F J Garhammer and F W Jobe Human patellar-tendon rupture J
Bone Joint Surg Am A-59179-183 1977 [Context Link]
WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
IMAGE GALLERY
Table 1
Figure 1-Weightlifte
Figure 2-Calculation
Figure 3-Individual
Figure 4-Mean maximu
Figure 5-Mean maximu
Figure 6-Schematic d
Back to Top
Copyright (c) 2000-2014 Ovid Technologies Inc
Terms of Use Support amp Training About Us Contact Us
Version OvidSP_UI031200116 SourceID 60384
Figure 4-Mean maximum moment of force with 95 confidence interval on the hip and
knee joints for the weightlifters and powerlifters during parallel squat and deep squat
(WE N = 8 PON = 6)
The weightlifters showed positive correlation between hip load and the total mass of lifter
and barbell The strongest correlation was found for the deep squat (r = 092) but the
correlation was also significant for the parallel squat (r = 088 P lt 001) There was also a
tendency to positive correlation between hip load and total mass for the powerlifters both for
the parallel (r = 075) and the deep (r = 076) squat but with only six lifters the correlation
was not significant The corresponding values for the knee joint showed that the moments of
force did not increase proportionally with external load This has been found earlier for world
class weightlifters (2)
Knee Forces
We thought it would be interesting to calculate one force component in the knee that
would reflect the magnitudes of the forces in the knee during squatting Therefore the
patello-femoral compression force for the parallel squat was calculated The mean peak
compression force for the weightlifters was 4700 N (SD plusmn 590) and for the powerlifters 3300 N
(SD plusmn 1700) (26)
Electromyography
The muscular activity in the vastus lateralis the rectus femoris and the biceps femoris
muscles was recorded and the mean muscular activity peaks with 95 confidence intervals
are shown in Figure 5 For all muscles and both the parallel and the deep squat the mean peak
muscular activity was higher for the powerlifters However in this study with six powerlifters
and eight weightlifters a significant difference was found only for the rectus femoris muscle
(P lt 005) The highest activity levels both for the weightlifters and the powerlifters were
found for the biceps femoris muscle with a relative muscular activity of about three times
the reference level However the activity in this muscle also showed the greatest individual
difference
Figure 5-Mean maximum muscular activity for the three muscles studied with 95
confidence interval 10 corresponds to the activity during the static reference
contraction (WE N = 8 PON = 6)
Movement and Joint Angles
The knee flexion angles were slightly smaller for the powerlifters The mean knee flexion
angle for the powerlifters were 111deg (SD plusmn 5) for the parallel and 126deg (SD plusmn 4) for the deep
squat The corresponding angles for the weightlifters was 116deg (SD plusmn 5) for the parallel and
138deg (SD plusmn 3) for the deep squat Analyses of the hip flexion angles show that both the
weightlifters and the powerlifters increased these angles with increasing squating depth The
mean maximal hip flexion angles for the weightlifters was 111deg (SD plusmn 8) during the parallel
squat and 125deg (SD plusmn 4) during the deep squat The corresponding angles for the power lifters
were 132deg (SD plusmn 4) and 146deg (SD plusmn 3) respectively By flexing the hip more the powerlifters
leaned the trunk farther forward (Fig 6)
Figure 6-Schematic drawing of the lowest position during the parallel squat A)
weightlifter B) powerlifter Measured angles are indicated the horizontal line indicates
the position of the thigh
DISCUSSION
Since squatting exercise is an important part of the strength training for many athletes
it is important to understand the effects of different squatting techniques In this study we
used weightlifters and powerlifters to demonstrate effects of the high- and low-bar squats
We are aware that there is a difference in age between the two lifter categories but the
analysis showed no difference in principle muscular activity or load between the oldest and
youngest lifters in each group
The study shows the differences between the high- and low-bar techniques and also the
effects on the hip and knee moment of force The low-bar squat with the barbell further
down on the back is characterized of a larger hip flexion (Fig 6) and this technique creates a
hip moment of force that in Newton-meter is almost twice as large as the knee moment The
high-bar squat however is performed more upright and the joint moment of force are more
equally distributed between the hip and knee joints The hip and knee angles in the present
study correlate well with the angles found by Fry et al (12) and confirm the more upright
position during the high-bar squat Although the powerlifters were larger and lifted heavier
loads than the weightlifters the mean moment of force on the knee joint was lower than for
the weightlifter and the difference was significant for the parallel squat The powerlifters
however had significantly a higher load on the hip joint compared with the weightlifters The
difference in hip load could be an effect of heavier lifters lifting heavier loads in addition to
an effect of different technique but the difference in knee moment of force could hardly be
explained from anything else but different lifting technique It is clear that weightlifter
coaches want the squat to be done as upright as possible This is the only way to approach the
movement during weightlifting competition Powerlifting coaches however want lifters to lift
as much as possible with hip and back since by experience they know that this enables the
lifter to lift heavier loads The calculated moment of force on the joint is dependent on the
size of the ground reaction force and the distance between this force and the joint center
the moment arm By increasing hip flexion the powerlifters manage to balance the weight
closer to the knee and thereby reduce the moment arm The moment arm between the
ground reaction force and the hip joint however will increase creating a higher moment of
force on this joint The high-bar squat is performed in a more balanced way where both the
barbell and the trunk center of gravity are centered between hip and knee and thereby the
moments of force are more equally distributed
The powerlifters showed higher EMG activity than the weightlifters for all investigated
muscles although the difference was significant only for the rectus femoris The powerlifters
were heavier and lifted heavier loads but this could be the explanation to the higher muscular
activity EMG activity however was normalized in relation to a reference contraction with
the same relative external load which might indicate that the low-bar squat actually is
advantageous from a muscular recruitment point of view It is clear however that
weightlifters must train with a technique close to the competition situation which means the
high-bar squat Some other athletes might benefit from using a technique close to the low-bar
squat providing that they have the low back strength to safely perform a low bar squat
It is a little surprising that powerlifters performing low-bar squats with relatively low
moment of force at the knee joints have a knee extensor muscular activity even slightly
higher than weightlifters performing high-bar squats with higher knee moments The
explanation must be that the moments calculated are net loading moments of force which
means that muscular co-contraction is not included in the values calculated The activity in the
biceps femoris muscle is slightly higher for the low-bar squat The activity in the
gastrocnemius muscle and the soleus muscle was not recorded However since the low-bar
squat is performed with the total center of gravity further forward the need for
compensatory ankle plantar flexion will increase which means increased activity in both the
gastrocnemius and the soleus muscles During the low-bar squat knee flexor muscle activity
increases and hereby knee extensor co-contraction This can explain why the knee extensor
activity is high despite the relatively low net knee loading moment As previously mentioned
one should be aware that the calculated moments are net moments of force and that the
effect of co-contracting antagonistic muscles are not taken into account A antagonistic
moment of force created by the antagonist would increase the moment of force produced by
the agonists Therefore the moment calculated in this study must be taken as minimum
loading moments for the agonists Two joint muscles can in this way serve as agonist at one
of the joints and antagonists at an other The biceps femoris for example produce an
extending moment of force at the hip but an antagonistic flexing moment of force at the
knee The magnitude of this antagonistic moment is not possible to calculate in a study like
this
Although hip extensor activity was not analyzed it seems logical that the low-bar squat
should be the best technique concerning hip extensor training since this technique create the
greatest moments of force at the joint
The patello-femoral compression force was calculated to give an apprehension of the
force magnitudes Forces in the hip and knee depend not only on the moment of force but
also on joint angle (222425) For a constant moment of force joint compression forces
increase with increasing flexion angle This has been investigated for hip flexion up to 90deg and
for knee flexion up to 120deg For the knee the patello-femoral compression force levels away
between 90 and 120deg So the reason for larger compression force in the knee for the
weightliftres was not because of a larger knee flexion angles rather related to the larger
moment of force
Both the weightlifters and powerlifters have a strict and precise squatting technique It is
probable that many other athletes in other disciplines use techniques in between the high- and
low-bar techniques and that their coaches are not aware of the effects of the different
techniques Athletes should benefit from studying lifters and their technique and the different
effects that can be achieved It is known that squatting exercise is a good method for knee
rehabilitation training (30) and we suggest that after a hip injury high-bar squat should be
used at the beginning to minimize the risk of hip overload After a knee injury a squatting
technique more similar to the low-bar technique should be preferred Further investigation
on for example shear and compression forces on the lumbar spine during the two different
types of squatting technique must be important to prevent reinjury of the lower back during
rehabilitation exercise
REFERENCES
1 Ariel B G Biomechanical analysis of the knee joint during deep knee bends with heavy
load In Biomechanics IV A J Nelson and C A Morehouse (Eds) Baltimore University
Park Press 1975 pp 44-52 [Context Link]
2 Baumann W V Gross K Quade P Galbierz and A Schwirtz The snatch technique of
world class weightlifters at the 1985 world championships Int J Sprots Biomech 468-89
1988 [Context Link]
3 Chandler T J and M H Stone The squat exercise in athletic conditioning a review of
the literature Natl Strength Condit Assoc J 1352-58 1991 [Context Link]
4 Coaches Roundtable The squat and its application to athletic performance Natl Strength
Condit Assoc J 610-22 1984 [Context Link]
5 Dahlkvist N J P Mayo and B B Seedhom Forces during squatting and rising from a
deep squat Eng Med 269-76 1982 [Context Link]
6 Dempster W T and G R L Gaughran Properties of body segments based on size and
weight Am J Anat 12033-54 1967 [Context Link]
7 Ekholm J R Nisell U P Arborelius C Hammarberg and G Nemeth Load on knee
joint structures and muscular activity during lifting Scand J Rehabil Med 161-9 1984
Bibliographic Links [Context Link]
8 Ekholm J R Nisell U P Arborelius O Svensson and G Nemeth Load on knee joint
and knee muscular activity during machine milking Ergonomics 4665-682 1985
Bibliographic Links [Context Link]
9 Ellis M I B B Seedhom A A Amis D Dowson and V Wright Forces in the knee joint
whilst rising from normal and motorized chairs Eng Med 133-40 1979 [Context Link]
10 Enoka R M The pull in Olympic weightliftingMed Sci Sports 2131-137 1979 [Context
Link]
11 Enoka R M Load- and skill-related changes in segmental contributions to a weightlifting
movement Med Sci Sports Exerc 2178-187 1988 [Context Link]
12 Fry A C T A Aro J A Bauer and W J Kraemer A comparison of methods for
determining kinematic properties of three barbell squat exercises J Hum Mov Stud 2483-
95 1993 [Context Link]
13 Garhammer J Performance evaluation of Olympic weightlifters Med Sci Sports 3284-
287 1979 [Context Link]
14 Garhammer J Power production by olympic weightlifters Med Sci Sports Exerc 154-
60 1980 [Context Link]
15 Garhammer J Biomechanical profiles of olympic weightlifters Int J Sports Biomech
1122-130 1985 [Context Link]
16 Grenier R and A Guimont Simultaneous bilateral rupture of the quadriceps tendon and
leg fractures in a weightlifterAm J Sports Med 6451-453 1983 Bibliographic Links
[Context Link]
[Context Link]
17 Hammarskjoumlld E K Harms-Ringdahl and J Ekholm Shoulder-arm muscular activity and
reproducibility in carpenters work Clin Biomech 581-87 1990 Bibliographic Links
[Context Link]
18 Hattin H C M R Pierrynowski and K A Ball Effect of load cadence and fatigue on
tibio-femoral joint force during a half squat Med Sci Sports Exerc 5613-618 1989
[Context Link]
19 Lander J F R L Simonton and J K F Giacobbe The effectiveness of weight-belts
during the squat exercise Med Sci Sports Exerc 22117-126 1990 Ovid Full Text
Bibliographic Links [Context Link]
20 Lander J E J R Hundley and R L Simonton The effectiveness of weight-belts
during multiple repetitions of the squat exercise Med Sci Sports Exerc 24603-609 1992
Ovid Full Text Bibliographic Links [Context Link]
21 Lindbeck L and U P Arborelius Inertial effects from single body segments in dynamic
analysis of lifting Ergonomics 4421-433 1991 Bibliographic Links [Context Link]
22 McLaughlin T M C J Dillman and T J Lardner A kinematic model of performance in
the parallel squat by champion powerliftersMed Sci Sports 2128-133 1977 [Context Link]
23 McLaughlin T M T J Lardner and C J Dillman Kinetics of the parallel squat Res Q
2175-189 1978 [Context Link]
24 Nemeth G and J Ekholm A biomechanical analysis of hip compression loading during
lifting Ergonomics 28429-440 1985 Bibliographic Links [Context Link]
25 Nemeth G J Ekholm and U P Arborelius Hip load moments and muscular activity
during lifting Scand J Rehabil Med 16103-111 1984 Bibliographic Links [Context Link]
26 Nemeth G J Ekholm U P Arborelius K Schlt951gtuldt and K Harms-Ringdahl Hip
joint load and muscular activation during rising exercises Scand J Rehabil Med 1693-102
1984 Bibliographic Links [Context Link]
27 Nisell R and J Ekholm Patellar forces during knee extension Scand J Rehabil Med
1763-74 1985 Bibliographic Links [Context Link]
28 Nisell R and J Ekholm Joint load during the parallel squat in powerlifting and forces of
in vivo bilateral quadriceps tendon rupture Scand J Sports Sci 863-70 1986 [Context
Link]
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Select All Export Selected to PowerPoint
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Link]
30 Palmitier R A K-N An S G Scott and E Y S Chao Kinetic chain exercise in knee
rehabilitation Sports Med 11402-413 1991 Ovid Full Text Bibliographic Links [Context
Link]
31 Weidenhielm L Knee osteoarthrosis aspects of clinical symptoms corrective surgery leg
alignment and knee joint load(Dissertation) Karolinska Institute Stockholm Sweden 1992
[Context Link]
32 Wretenberg P F Yi F Lindberg and U P Arborelius Joint moment of force and
quadriceps muscle activity during squatting exercise Scand J Med Sci Sports 3244-250
1993 Bibliographic Links [Context Link]
33 Zernicke R F J Garhammer and F W Jobe Human patellar-tendon rupture J
Bone Joint Surg Am A-59179-183 1977 [Context Link]
WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
IMAGE GALLERY
Table 1
Figure 1-Weightlifte
Figure 2-Calculation
Figure 3-Individual
Figure 4-Mean maximu
Figure 5-Mean maximu
Figure 6-Schematic d
Back to Top
Copyright (c) 2000-2014 Ovid Technologies Inc
Terms of Use Support amp Training About Us Contact Us
Version OvidSP_UI031200116 SourceID 60384
Figure 5-Mean maximum muscular activity for the three muscles studied with 95
confidence interval 10 corresponds to the activity during the static reference
contraction (WE N = 8 PON = 6)
Movement and Joint Angles
The knee flexion angles were slightly smaller for the powerlifters The mean knee flexion
angle for the powerlifters were 111deg (SD plusmn 5) for the parallel and 126deg (SD plusmn 4) for the deep
squat The corresponding angles for the weightlifters was 116deg (SD plusmn 5) for the parallel and
138deg (SD plusmn 3) for the deep squat Analyses of the hip flexion angles show that both the
weightlifters and the powerlifters increased these angles with increasing squating depth The
mean maximal hip flexion angles for the weightlifters was 111deg (SD plusmn 8) during the parallel
squat and 125deg (SD plusmn 4) during the deep squat The corresponding angles for the power lifters
were 132deg (SD plusmn 4) and 146deg (SD plusmn 3) respectively By flexing the hip more the powerlifters
leaned the trunk farther forward (Fig 6)
Figure 6-Schematic drawing of the lowest position during the parallel squat A)
weightlifter B) powerlifter Measured angles are indicated the horizontal line indicates
the position of the thigh
DISCUSSION
Since squatting exercise is an important part of the strength training for many athletes
it is important to understand the effects of different squatting techniques In this study we
used weightlifters and powerlifters to demonstrate effects of the high- and low-bar squats
We are aware that there is a difference in age between the two lifter categories but the
analysis showed no difference in principle muscular activity or load between the oldest and
youngest lifters in each group
The study shows the differences between the high- and low-bar techniques and also the
effects on the hip and knee moment of force The low-bar squat with the barbell further
down on the back is characterized of a larger hip flexion (Fig 6) and this technique creates a
hip moment of force that in Newton-meter is almost twice as large as the knee moment The
high-bar squat however is performed more upright and the joint moment of force are more
equally distributed between the hip and knee joints The hip and knee angles in the present
study correlate well with the angles found by Fry et al (12) and confirm the more upright
position during the high-bar squat Although the powerlifters were larger and lifted heavier
loads than the weightlifters the mean moment of force on the knee joint was lower than for
the weightlifter and the difference was significant for the parallel squat The powerlifters
however had significantly a higher load on the hip joint compared with the weightlifters The
difference in hip load could be an effect of heavier lifters lifting heavier loads in addition to
an effect of different technique but the difference in knee moment of force could hardly be
explained from anything else but different lifting technique It is clear that weightlifter
coaches want the squat to be done as upright as possible This is the only way to approach the
movement during weightlifting competition Powerlifting coaches however want lifters to lift
as much as possible with hip and back since by experience they know that this enables the
lifter to lift heavier loads The calculated moment of force on the joint is dependent on the
size of the ground reaction force and the distance between this force and the joint center
the moment arm By increasing hip flexion the powerlifters manage to balance the weight
closer to the knee and thereby reduce the moment arm The moment arm between the
ground reaction force and the hip joint however will increase creating a higher moment of
force on this joint The high-bar squat is performed in a more balanced way where both the
barbell and the trunk center of gravity are centered between hip and knee and thereby the
moments of force are more equally distributed
The powerlifters showed higher EMG activity than the weightlifters for all investigated
muscles although the difference was significant only for the rectus femoris The powerlifters
were heavier and lifted heavier loads but this could be the explanation to the higher muscular
activity EMG activity however was normalized in relation to a reference contraction with
the same relative external load which might indicate that the low-bar squat actually is
advantageous from a muscular recruitment point of view It is clear however that
weightlifters must train with a technique close to the competition situation which means the
high-bar squat Some other athletes might benefit from using a technique close to the low-bar
squat providing that they have the low back strength to safely perform a low bar squat
It is a little surprising that powerlifters performing low-bar squats with relatively low
moment of force at the knee joints have a knee extensor muscular activity even slightly
higher than weightlifters performing high-bar squats with higher knee moments The
explanation must be that the moments calculated are net loading moments of force which
means that muscular co-contraction is not included in the values calculated The activity in the
biceps femoris muscle is slightly higher for the low-bar squat The activity in the
gastrocnemius muscle and the soleus muscle was not recorded However since the low-bar
squat is performed with the total center of gravity further forward the need for
compensatory ankle plantar flexion will increase which means increased activity in both the
gastrocnemius and the soleus muscles During the low-bar squat knee flexor muscle activity
increases and hereby knee extensor co-contraction This can explain why the knee extensor
activity is high despite the relatively low net knee loading moment As previously mentioned
one should be aware that the calculated moments are net moments of force and that the
effect of co-contracting antagonistic muscles are not taken into account A antagonistic
moment of force created by the antagonist would increase the moment of force produced by
the agonists Therefore the moment calculated in this study must be taken as minimum
loading moments for the agonists Two joint muscles can in this way serve as agonist at one
of the joints and antagonists at an other The biceps femoris for example produce an
extending moment of force at the hip but an antagonistic flexing moment of force at the
knee The magnitude of this antagonistic moment is not possible to calculate in a study like
this
Although hip extensor activity was not analyzed it seems logical that the low-bar squat
should be the best technique concerning hip extensor training since this technique create the
greatest moments of force at the joint
The patello-femoral compression force was calculated to give an apprehension of the
force magnitudes Forces in the hip and knee depend not only on the moment of force but
also on joint angle (222425) For a constant moment of force joint compression forces
increase with increasing flexion angle This has been investigated for hip flexion up to 90deg and
for knee flexion up to 120deg For the knee the patello-femoral compression force levels away
between 90 and 120deg So the reason for larger compression force in the knee for the
weightliftres was not because of a larger knee flexion angles rather related to the larger
moment of force
Both the weightlifters and powerlifters have a strict and precise squatting technique It is
probable that many other athletes in other disciplines use techniques in between the high- and
low-bar techniques and that their coaches are not aware of the effects of the different
techniques Athletes should benefit from studying lifters and their technique and the different
effects that can be achieved It is known that squatting exercise is a good method for knee
rehabilitation training (30) and we suggest that after a hip injury high-bar squat should be
used at the beginning to minimize the risk of hip overload After a knee injury a squatting
technique more similar to the low-bar technique should be preferred Further investigation
on for example shear and compression forces on the lumbar spine during the two different
types of squatting technique must be important to prevent reinjury of the lower back during
rehabilitation exercise
REFERENCES
1 Ariel B G Biomechanical analysis of the knee joint during deep knee bends with heavy
load In Biomechanics IV A J Nelson and C A Morehouse (Eds) Baltimore University
Park Press 1975 pp 44-52 [Context Link]
2 Baumann W V Gross K Quade P Galbierz and A Schwirtz The snatch technique of
world class weightlifters at the 1985 world championships Int J Sprots Biomech 468-89
1988 [Context Link]
3 Chandler T J and M H Stone The squat exercise in athletic conditioning a review of
the literature Natl Strength Condit Assoc J 1352-58 1991 [Context Link]
4 Coaches Roundtable The squat and its application to athletic performance Natl Strength
Condit Assoc J 610-22 1984 [Context Link]
5 Dahlkvist N J P Mayo and B B Seedhom Forces during squatting and rising from a
deep squat Eng Med 269-76 1982 [Context Link]
6 Dempster W T and G R L Gaughran Properties of body segments based on size and
weight Am J Anat 12033-54 1967 [Context Link]
7 Ekholm J R Nisell U P Arborelius C Hammarberg and G Nemeth Load on knee
joint structures and muscular activity during lifting Scand J Rehabil Med 161-9 1984
Bibliographic Links [Context Link]
8 Ekholm J R Nisell U P Arborelius O Svensson and G Nemeth Load on knee joint
and knee muscular activity during machine milking Ergonomics 4665-682 1985
Bibliographic Links [Context Link]
9 Ellis M I B B Seedhom A A Amis D Dowson and V Wright Forces in the knee joint
whilst rising from normal and motorized chairs Eng Med 133-40 1979 [Context Link]
10 Enoka R M The pull in Olympic weightliftingMed Sci Sports 2131-137 1979 [Context
Link]
11 Enoka R M Load- and skill-related changes in segmental contributions to a weightlifting
movement Med Sci Sports Exerc 2178-187 1988 [Context Link]
12 Fry A C T A Aro J A Bauer and W J Kraemer A comparison of methods for
determining kinematic properties of three barbell squat exercises J Hum Mov Stud 2483-
95 1993 [Context Link]
13 Garhammer J Performance evaluation of Olympic weightlifters Med Sci Sports 3284-
287 1979 [Context Link]
14 Garhammer J Power production by olympic weightlifters Med Sci Sports Exerc 154-
60 1980 [Context Link]
15 Garhammer J Biomechanical profiles of olympic weightlifters Int J Sports Biomech
1122-130 1985 [Context Link]
16 Grenier R and A Guimont Simultaneous bilateral rupture of the quadriceps tendon and
leg fractures in a weightlifterAm J Sports Med 6451-453 1983 Bibliographic Links
[Context Link]
[Context Link]
17 Hammarskjoumlld E K Harms-Ringdahl and J Ekholm Shoulder-arm muscular activity and
reproducibility in carpenters work Clin Biomech 581-87 1990 Bibliographic Links
[Context Link]
18 Hattin H C M R Pierrynowski and K A Ball Effect of load cadence and fatigue on
tibio-femoral joint force during a half squat Med Sci Sports Exerc 5613-618 1989
[Context Link]
19 Lander J F R L Simonton and J K F Giacobbe The effectiveness of weight-belts
during the squat exercise Med Sci Sports Exerc 22117-126 1990 Ovid Full Text
Bibliographic Links [Context Link]
20 Lander J E J R Hundley and R L Simonton The effectiveness of weight-belts
during multiple repetitions of the squat exercise Med Sci Sports Exerc 24603-609 1992
Ovid Full Text Bibliographic Links [Context Link]
21 Lindbeck L and U P Arborelius Inertial effects from single body segments in dynamic
analysis of lifting Ergonomics 4421-433 1991 Bibliographic Links [Context Link]
22 McLaughlin T M C J Dillman and T J Lardner A kinematic model of performance in
the parallel squat by champion powerliftersMed Sci Sports 2128-133 1977 [Context Link]
23 McLaughlin T M T J Lardner and C J Dillman Kinetics of the parallel squat Res Q
2175-189 1978 [Context Link]
24 Nemeth G and J Ekholm A biomechanical analysis of hip compression loading during
lifting Ergonomics 28429-440 1985 Bibliographic Links [Context Link]
25 Nemeth G J Ekholm and U P Arborelius Hip load moments and muscular activity
during lifting Scand J Rehabil Med 16103-111 1984 Bibliographic Links [Context Link]
26 Nemeth G J Ekholm U P Arborelius K Schlt951gtuldt and K Harms-Ringdahl Hip
joint load and muscular activation during rising exercises Scand J Rehabil Med 1693-102
1984 Bibliographic Links [Context Link]
27 Nisell R and J Ekholm Patellar forces during knee extension Scand J Rehabil Med
1763-74 1985 Bibliographic Links [Context Link]
28 Nisell R and J Ekholm Joint load during the parallel squat in powerlifting and forces of
in vivo bilateral quadriceps tendon rupture Scand J Sports Sci 863-70 1986 [Context
Link]
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Select All Export Selected to PowerPoint
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Link]
30 Palmitier R A K-N An S G Scott and E Y S Chao Kinetic chain exercise in knee
rehabilitation Sports Med 11402-413 1991 Ovid Full Text Bibliographic Links [Context
Link]
31 Weidenhielm L Knee osteoarthrosis aspects of clinical symptoms corrective surgery leg
alignment and knee joint load(Dissertation) Karolinska Institute Stockholm Sweden 1992
[Context Link]
32 Wretenberg P F Yi F Lindberg and U P Arborelius Joint moment of force and
quadriceps muscle activity during squatting exercise Scand J Med Sci Sports 3244-250
1993 Bibliographic Links [Context Link]
33 Zernicke R F J Garhammer and F W Jobe Human patellar-tendon rupture J
Bone Joint Surg Am A-59179-183 1977 [Context Link]
WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
IMAGE GALLERY
Table 1
Figure 1-Weightlifte
Figure 2-Calculation
Figure 3-Individual
Figure 4-Mean maximu
Figure 5-Mean maximu
Figure 6-Schematic d
Back to Top
Copyright (c) 2000-2014 Ovid Technologies Inc
Terms of Use Support amp Training About Us Contact Us
Version OvidSP_UI031200116 SourceID 60384
Figure 6-Schematic drawing of the lowest position during the parallel squat A)
weightlifter B) powerlifter Measured angles are indicated the horizontal line indicates
the position of the thigh
DISCUSSION
Since squatting exercise is an important part of the strength training for many athletes
it is important to understand the effects of different squatting techniques In this study we
used weightlifters and powerlifters to demonstrate effects of the high- and low-bar squats
We are aware that there is a difference in age between the two lifter categories but the
analysis showed no difference in principle muscular activity or load between the oldest and
youngest lifters in each group
The study shows the differences between the high- and low-bar techniques and also the
effects on the hip and knee moment of force The low-bar squat with the barbell further
down on the back is characterized of a larger hip flexion (Fig 6) and this technique creates a
hip moment of force that in Newton-meter is almost twice as large as the knee moment The
high-bar squat however is performed more upright and the joint moment of force are more
equally distributed between the hip and knee joints The hip and knee angles in the present
study correlate well with the angles found by Fry et al (12) and confirm the more upright
position during the high-bar squat Although the powerlifters were larger and lifted heavier
loads than the weightlifters the mean moment of force on the knee joint was lower than for
the weightlifter and the difference was significant for the parallel squat The powerlifters
however had significantly a higher load on the hip joint compared with the weightlifters The
difference in hip load could be an effect of heavier lifters lifting heavier loads in addition to
an effect of different technique but the difference in knee moment of force could hardly be
explained from anything else but different lifting technique It is clear that weightlifter
coaches want the squat to be done as upright as possible This is the only way to approach the
movement during weightlifting competition Powerlifting coaches however want lifters to lift
as much as possible with hip and back since by experience they know that this enables the
lifter to lift heavier loads The calculated moment of force on the joint is dependent on the
size of the ground reaction force and the distance between this force and the joint center
the moment arm By increasing hip flexion the powerlifters manage to balance the weight
closer to the knee and thereby reduce the moment arm The moment arm between the
ground reaction force and the hip joint however will increase creating a higher moment of
force on this joint The high-bar squat is performed in a more balanced way where both the
barbell and the trunk center of gravity are centered between hip and knee and thereby the
moments of force are more equally distributed
The powerlifters showed higher EMG activity than the weightlifters for all investigated
muscles although the difference was significant only for the rectus femoris The powerlifters
were heavier and lifted heavier loads but this could be the explanation to the higher muscular
activity EMG activity however was normalized in relation to a reference contraction with
the same relative external load which might indicate that the low-bar squat actually is
advantageous from a muscular recruitment point of view It is clear however that
weightlifters must train with a technique close to the competition situation which means the
high-bar squat Some other athletes might benefit from using a technique close to the low-bar
squat providing that they have the low back strength to safely perform a low bar squat
It is a little surprising that powerlifters performing low-bar squats with relatively low
moment of force at the knee joints have a knee extensor muscular activity even slightly
higher than weightlifters performing high-bar squats with higher knee moments The
explanation must be that the moments calculated are net loading moments of force which
means that muscular co-contraction is not included in the values calculated The activity in the
biceps femoris muscle is slightly higher for the low-bar squat The activity in the
gastrocnemius muscle and the soleus muscle was not recorded However since the low-bar
squat is performed with the total center of gravity further forward the need for
compensatory ankle plantar flexion will increase which means increased activity in both the
gastrocnemius and the soleus muscles During the low-bar squat knee flexor muscle activity
increases and hereby knee extensor co-contraction This can explain why the knee extensor
activity is high despite the relatively low net knee loading moment As previously mentioned
one should be aware that the calculated moments are net moments of force and that the
effect of co-contracting antagonistic muscles are not taken into account A antagonistic
moment of force created by the antagonist would increase the moment of force produced by
the agonists Therefore the moment calculated in this study must be taken as minimum
loading moments for the agonists Two joint muscles can in this way serve as agonist at one
of the joints and antagonists at an other The biceps femoris for example produce an
extending moment of force at the hip but an antagonistic flexing moment of force at the
knee The magnitude of this antagonistic moment is not possible to calculate in a study like
this
Although hip extensor activity was not analyzed it seems logical that the low-bar squat
should be the best technique concerning hip extensor training since this technique create the
greatest moments of force at the joint
The patello-femoral compression force was calculated to give an apprehension of the
force magnitudes Forces in the hip and knee depend not only on the moment of force but
also on joint angle (222425) For a constant moment of force joint compression forces
increase with increasing flexion angle This has been investigated for hip flexion up to 90deg and
for knee flexion up to 120deg For the knee the patello-femoral compression force levels away
between 90 and 120deg So the reason for larger compression force in the knee for the
weightliftres was not because of a larger knee flexion angles rather related to the larger
moment of force
Both the weightlifters and powerlifters have a strict and precise squatting technique It is
probable that many other athletes in other disciplines use techniques in between the high- and
low-bar techniques and that their coaches are not aware of the effects of the different
techniques Athletes should benefit from studying lifters and their technique and the different
effects that can be achieved It is known that squatting exercise is a good method for knee
rehabilitation training (30) and we suggest that after a hip injury high-bar squat should be
used at the beginning to minimize the risk of hip overload After a knee injury a squatting
technique more similar to the low-bar technique should be preferred Further investigation
on for example shear and compression forces on the lumbar spine during the two different
types of squatting technique must be important to prevent reinjury of the lower back during
rehabilitation exercise
REFERENCES
1 Ariel B G Biomechanical analysis of the knee joint during deep knee bends with heavy
load In Biomechanics IV A J Nelson and C A Morehouse (Eds) Baltimore University
Park Press 1975 pp 44-52 [Context Link]
2 Baumann W V Gross K Quade P Galbierz and A Schwirtz The snatch technique of
world class weightlifters at the 1985 world championships Int J Sprots Biomech 468-89
1988 [Context Link]
3 Chandler T J and M H Stone The squat exercise in athletic conditioning a review of
the literature Natl Strength Condit Assoc J 1352-58 1991 [Context Link]
4 Coaches Roundtable The squat and its application to athletic performance Natl Strength
Condit Assoc J 610-22 1984 [Context Link]
5 Dahlkvist N J P Mayo and B B Seedhom Forces during squatting and rising from a
deep squat Eng Med 269-76 1982 [Context Link]
6 Dempster W T and G R L Gaughran Properties of body segments based on size and
weight Am J Anat 12033-54 1967 [Context Link]
7 Ekholm J R Nisell U P Arborelius C Hammarberg and G Nemeth Load on knee
joint structures and muscular activity during lifting Scand J Rehabil Med 161-9 1984
Bibliographic Links [Context Link]
8 Ekholm J R Nisell U P Arborelius O Svensson and G Nemeth Load on knee joint
and knee muscular activity during machine milking Ergonomics 4665-682 1985
Bibliographic Links [Context Link]
9 Ellis M I B B Seedhom A A Amis D Dowson and V Wright Forces in the knee joint
whilst rising from normal and motorized chairs Eng Med 133-40 1979 [Context Link]
10 Enoka R M The pull in Olympic weightliftingMed Sci Sports 2131-137 1979 [Context
Link]
11 Enoka R M Load- and skill-related changes in segmental contributions to a weightlifting
movement Med Sci Sports Exerc 2178-187 1988 [Context Link]
12 Fry A C T A Aro J A Bauer and W J Kraemer A comparison of methods for
determining kinematic properties of three barbell squat exercises J Hum Mov Stud 2483-
95 1993 [Context Link]
13 Garhammer J Performance evaluation of Olympic weightlifters Med Sci Sports 3284-
287 1979 [Context Link]
14 Garhammer J Power production by olympic weightlifters Med Sci Sports Exerc 154-
60 1980 [Context Link]
15 Garhammer J Biomechanical profiles of olympic weightlifters Int J Sports Biomech
1122-130 1985 [Context Link]
16 Grenier R and A Guimont Simultaneous bilateral rupture of the quadriceps tendon and
leg fractures in a weightlifterAm J Sports Med 6451-453 1983 Bibliographic Links
[Context Link]
[Context Link]
17 Hammarskjoumlld E K Harms-Ringdahl and J Ekholm Shoulder-arm muscular activity and
reproducibility in carpenters work Clin Biomech 581-87 1990 Bibliographic Links
[Context Link]
18 Hattin H C M R Pierrynowski and K A Ball Effect of load cadence and fatigue on
tibio-femoral joint force during a half squat Med Sci Sports Exerc 5613-618 1989
[Context Link]
19 Lander J F R L Simonton and J K F Giacobbe The effectiveness of weight-belts
during the squat exercise Med Sci Sports Exerc 22117-126 1990 Ovid Full Text
Bibliographic Links [Context Link]
20 Lander J E J R Hundley and R L Simonton The effectiveness of weight-belts
during multiple repetitions of the squat exercise Med Sci Sports Exerc 24603-609 1992
Ovid Full Text Bibliographic Links [Context Link]
21 Lindbeck L and U P Arborelius Inertial effects from single body segments in dynamic
analysis of lifting Ergonomics 4421-433 1991 Bibliographic Links [Context Link]
22 McLaughlin T M C J Dillman and T J Lardner A kinematic model of performance in
the parallel squat by champion powerliftersMed Sci Sports 2128-133 1977 [Context Link]
23 McLaughlin T M T J Lardner and C J Dillman Kinetics of the parallel squat Res Q
2175-189 1978 [Context Link]
24 Nemeth G and J Ekholm A biomechanical analysis of hip compression loading during
lifting Ergonomics 28429-440 1985 Bibliographic Links [Context Link]
25 Nemeth G J Ekholm and U P Arborelius Hip load moments and muscular activity
during lifting Scand J Rehabil Med 16103-111 1984 Bibliographic Links [Context Link]
26 Nemeth G J Ekholm U P Arborelius K Schlt951gtuldt and K Harms-Ringdahl Hip
joint load and muscular activation during rising exercises Scand J Rehabil Med 1693-102
1984 Bibliographic Links [Context Link]
27 Nisell R and J Ekholm Patellar forces during knee extension Scand J Rehabil Med
1763-74 1985 Bibliographic Links [Context Link]
28 Nisell R and J Ekholm Joint load during the parallel squat in powerlifting and forces of
in vivo bilateral quadriceps tendon rupture Scand J Sports Sci 863-70 1986 [Context
Link]
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Select All Export Selected to PowerPoint
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Link]
30 Palmitier R A K-N An S G Scott and E Y S Chao Kinetic chain exercise in knee
rehabilitation Sports Med 11402-413 1991 Ovid Full Text Bibliographic Links [Context
Link]
31 Weidenhielm L Knee osteoarthrosis aspects of clinical symptoms corrective surgery leg
alignment and knee joint load(Dissertation) Karolinska Institute Stockholm Sweden 1992
[Context Link]
32 Wretenberg P F Yi F Lindberg and U P Arborelius Joint moment of force and
quadriceps muscle activity during squatting exercise Scand J Med Sci Sports 3244-250
1993 Bibliographic Links [Context Link]
33 Zernicke R F J Garhammer and F W Jobe Human patellar-tendon rupture J
Bone Joint Surg Am A-59179-183 1977 [Context Link]
WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
IMAGE GALLERY
Table 1
Figure 1-Weightlifte
Figure 2-Calculation
Figure 3-Individual
Figure 4-Mean maximu
Figure 5-Mean maximu
Figure 6-Schematic d
Back to Top
Copyright (c) 2000-2014 Ovid Technologies Inc
Terms of Use Support amp Training About Us Contact Us
Version OvidSP_UI031200116 SourceID 60384
gastrocnemius muscle and the soleus muscle was not recorded However since the low-bar
squat is performed with the total center of gravity further forward the need for
compensatory ankle plantar flexion will increase which means increased activity in both the
gastrocnemius and the soleus muscles During the low-bar squat knee flexor muscle activity
increases and hereby knee extensor co-contraction This can explain why the knee extensor
activity is high despite the relatively low net knee loading moment As previously mentioned
one should be aware that the calculated moments are net moments of force and that the
effect of co-contracting antagonistic muscles are not taken into account A antagonistic
moment of force created by the antagonist would increase the moment of force produced by
the agonists Therefore the moment calculated in this study must be taken as minimum
loading moments for the agonists Two joint muscles can in this way serve as agonist at one
of the joints and antagonists at an other The biceps femoris for example produce an
extending moment of force at the hip but an antagonistic flexing moment of force at the
knee The magnitude of this antagonistic moment is not possible to calculate in a study like
this
Although hip extensor activity was not analyzed it seems logical that the low-bar squat
should be the best technique concerning hip extensor training since this technique create the
greatest moments of force at the joint
The patello-femoral compression force was calculated to give an apprehension of the
force magnitudes Forces in the hip and knee depend not only on the moment of force but
also on joint angle (222425) For a constant moment of force joint compression forces
increase with increasing flexion angle This has been investigated for hip flexion up to 90deg and
for knee flexion up to 120deg For the knee the patello-femoral compression force levels away
between 90 and 120deg So the reason for larger compression force in the knee for the
weightliftres was not because of a larger knee flexion angles rather related to the larger
moment of force
Both the weightlifters and powerlifters have a strict and precise squatting technique It is
probable that many other athletes in other disciplines use techniques in between the high- and
low-bar techniques and that their coaches are not aware of the effects of the different
techniques Athletes should benefit from studying lifters and their technique and the different
effects that can be achieved It is known that squatting exercise is a good method for knee
rehabilitation training (30) and we suggest that after a hip injury high-bar squat should be
used at the beginning to minimize the risk of hip overload After a knee injury a squatting
technique more similar to the low-bar technique should be preferred Further investigation
on for example shear and compression forces on the lumbar spine during the two different
types of squatting technique must be important to prevent reinjury of the lower back during
rehabilitation exercise
REFERENCES
1 Ariel B G Biomechanical analysis of the knee joint during deep knee bends with heavy
load In Biomechanics IV A J Nelson and C A Morehouse (Eds) Baltimore University
Park Press 1975 pp 44-52 [Context Link]
2 Baumann W V Gross K Quade P Galbierz and A Schwirtz The snatch technique of
world class weightlifters at the 1985 world championships Int J Sprots Biomech 468-89
1988 [Context Link]
3 Chandler T J and M H Stone The squat exercise in athletic conditioning a review of
the literature Natl Strength Condit Assoc J 1352-58 1991 [Context Link]
4 Coaches Roundtable The squat and its application to athletic performance Natl Strength
Condit Assoc J 610-22 1984 [Context Link]
5 Dahlkvist N J P Mayo and B B Seedhom Forces during squatting and rising from a
deep squat Eng Med 269-76 1982 [Context Link]
6 Dempster W T and G R L Gaughran Properties of body segments based on size and
weight Am J Anat 12033-54 1967 [Context Link]
7 Ekholm J R Nisell U P Arborelius C Hammarberg and G Nemeth Load on knee
joint structures and muscular activity during lifting Scand J Rehabil Med 161-9 1984
Bibliographic Links [Context Link]
8 Ekholm J R Nisell U P Arborelius O Svensson and G Nemeth Load on knee joint
and knee muscular activity during machine milking Ergonomics 4665-682 1985
Bibliographic Links [Context Link]
9 Ellis M I B B Seedhom A A Amis D Dowson and V Wright Forces in the knee joint
whilst rising from normal and motorized chairs Eng Med 133-40 1979 [Context Link]
10 Enoka R M The pull in Olympic weightliftingMed Sci Sports 2131-137 1979 [Context
Link]
11 Enoka R M Load- and skill-related changes in segmental contributions to a weightlifting
movement Med Sci Sports Exerc 2178-187 1988 [Context Link]
12 Fry A C T A Aro J A Bauer and W J Kraemer A comparison of methods for
determining kinematic properties of three barbell squat exercises J Hum Mov Stud 2483-
95 1993 [Context Link]
13 Garhammer J Performance evaluation of Olympic weightlifters Med Sci Sports 3284-
287 1979 [Context Link]
14 Garhammer J Power production by olympic weightlifters Med Sci Sports Exerc 154-
60 1980 [Context Link]
15 Garhammer J Biomechanical profiles of olympic weightlifters Int J Sports Biomech
1122-130 1985 [Context Link]
16 Grenier R and A Guimont Simultaneous bilateral rupture of the quadriceps tendon and
leg fractures in a weightlifterAm J Sports Med 6451-453 1983 Bibliographic Links
[Context Link]
[Context Link]
17 Hammarskjoumlld E K Harms-Ringdahl and J Ekholm Shoulder-arm muscular activity and
reproducibility in carpenters work Clin Biomech 581-87 1990 Bibliographic Links
[Context Link]
18 Hattin H C M R Pierrynowski and K A Ball Effect of load cadence and fatigue on
tibio-femoral joint force during a half squat Med Sci Sports Exerc 5613-618 1989
[Context Link]
19 Lander J F R L Simonton and J K F Giacobbe The effectiveness of weight-belts
during the squat exercise Med Sci Sports Exerc 22117-126 1990 Ovid Full Text
Bibliographic Links [Context Link]
20 Lander J E J R Hundley and R L Simonton The effectiveness of weight-belts
during multiple repetitions of the squat exercise Med Sci Sports Exerc 24603-609 1992
Ovid Full Text Bibliographic Links [Context Link]
21 Lindbeck L and U P Arborelius Inertial effects from single body segments in dynamic
analysis of lifting Ergonomics 4421-433 1991 Bibliographic Links [Context Link]
22 McLaughlin T M C J Dillman and T J Lardner A kinematic model of performance in
the parallel squat by champion powerliftersMed Sci Sports 2128-133 1977 [Context Link]
23 McLaughlin T M T J Lardner and C J Dillman Kinetics of the parallel squat Res Q
2175-189 1978 [Context Link]
24 Nemeth G and J Ekholm A biomechanical analysis of hip compression loading during
lifting Ergonomics 28429-440 1985 Bibliographic Links [Context Link]
25 Nemeth G J Ekholm and U P Arborelius Hip load moments and muscular activity
during lifting Scand J Rehabil Med 16103-111 1984 Bibliographic Links [Context Link]
26 Nemeth G J Ekholm U P Arborelius K Schlt951gtuldt and K Harms-Ringdahl Hip
joint load and muscular activation during rising exercises Scand J Rehabil Med 1693-102
1984 Bibliographic Links [Context Link]
27 Nisell R and J Ekholm Patellar forces during knee extension Scand J Rehabil Med
1763-74 1985 Bibliographic Links [Context Link]
28 Nisell R and J Ekholm Joint load during the parallel squat in powerlifting and forces of
in vivo bilateral quadriceps tendon rupture Scand J Sports Sci 863-70 1986 [Context
Link]
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Select All Export Selected to PowerPoint
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Link]
30 Palmitier R A K-N An S G Scott and E Y S Chao Kinetic chain exercise in knee
rehabilitation Sports Med 11402-413 1991 Ovid Full Text Bibliographic Links [Context
Link]
31 Weidenhielm L Knee osteoarthrosis aspects of clinical symptoms corrective surgery leg
alignment and knee joint load(Dissertation) Karolinska Institute Stockholm Sweden 1992
[Context Link]
32 Wretenberg P F Yi F Lindberg and U P Arborelius Joint moment of force and
quadriceps muscle activity during squatting exercise Scand J Med Sci Sports 3244-250
1993 Bibliographic Links [Context Link]
33 Zernicke R F J Garhammer and F W Jobe Human patellar-tendon rupture J
Bone Joint Surg Am A-59179-183 1977 [Context Link]
WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
IMAGE GALLERY
Table 1
Figure 1-Weightlifte
Figure 2-Calculation
Figure 3-Individual
Figure 4-Mean maximu
Figure 5-Mean maximu
Figure 6-Schematic d
Back to Top
Copyright (c) 2000-2014 Ovid Technologies Inc
Terms of Use Support amp Training About Us Contact Us
Version OvidSP_UI031200116 SourceID 60384
3 Chandler T J and M H Stone The squat exercise in athletic conditioning a review of
the literature Natl Strength Condit Assoc J 1352-58 1991 [Context Link]
4 Coaches Roundtable The squat and its application to athletic performance Natl Strength
Condit Assoc J 610-22 1984 [Context Link]
5 Dahlkvist N J P Mayo and B B Seedhom Forces during squatting and rising from a
deep squat Eng Med 269-76 1982 [Context Link]
6 Dempster W T and G R L Gaughran Properties of body segments based on size and
weight Am J Anat 12033-54 1967 [Context Link]
7 Ekholm J R Nisell U P Arborelius C Hammarberg and G Nemeth Load on knee
joint structures and muscular activity during lifting Scand J Rehabil Med 161-9 1984
Bibliographic Links [Context Link]
8 Ekholm J R Nisell U P Arborelius O Svensson and G Nemeth Load on knee joint
and knee muscular activity during machine milking Ergonomics 4665-682 1985
Bibliographic Links [Context Link]
9 Ellis M I B B Seedhom A A Amis D Dowson and V Wright Forces in the knee joint
whilst rising from normal and motorized chairs Eng Med 133-40 1979 [Context Link]
10 Enoka R M The pull in Olympic weightliftingMed Sci Sports 2131-137 1979 [Context
Link]
11 Enoka R M Load- and skill-related changes in segmental contributions to a weightlifting
movement Med Sci Sports Exerc 2178-187 1988 [Context Link]
12 Fry A C T A Aro J A Bauer and W J Kraemer A comparison of methods for
determining kinematic properties of three barbell squat exercises J Hum Mov Stud 2483-
95 1993 [Context Link]
13 Garhammer J Performance evaluation of Olympic weightlifters Med Sci Sports 3284-
287 1979 [Context Link]
14 Garhammer J Power production by olympic weightlifters Med Sci Sports Exerc 154-
60 1980 [Context Link]
15 Garhammer J Biomechanical profiles of olympic weightlifters Int J Sports Biomech
1122-130 1985 [Context Link]
16 Grenier R and A Guimont Simultaneous bilateral rupture of the quadriceps tendon and
leg fractures in a weightlifterAm J Sports Med 6451-453 1983 Bibliographic Links
[Context Link]
[Context Link]
17 Hammarskjoumlld E K Harms-Ringdahl and J Ekholm Shoulder-arm muscular activity and
reproducibility in carpenters work Clin Biomech 581-87 1990 Bibliographic Links
[Context Link]
18 Hattin H C M R Pierrynowski and K A Ball Effect of load cadence and fatigue on
tibio-femoral joint force during a half squat Med Sci Sports Exerc 5613-618 1989
[Context Link]
19 Lander J F R L Simonton and J K F Giacobbe The effectiveness of weight-belts
during the squat exercise Med Sci Sports Exerc 22117-126 1990 Ovid Full Text
Bibliographic Links [Context Link]
20 Lander J E J R Hundley and R L Simonton The effectiveness of weight-belts
during multiple repetitions of the squat exercise Med Sci Sports Exerc 24603-609 1992
Ovid Full Text Bibliographic Links [Context Link]
21 Lindbeck L and U P Arborelius Inertial effects from single body segments in dynamic
analysis of lifting Ergonomics 4421-433 1991 Bibliographic Links [Context Link]
22 McLaughlin T M C J Dillman and T J Lardner A kinematic model of performance in
the parallel squat by champion powerliftersMed Sci Sports 2128-133 1977 [Context Link]
23 McLaughlin T M T J Lardner and C J Dillman Kinetics of the parallel squat Res Q
2175-189 1978 [Context Link]
24 Nemeth G and J Ekholm A biomechanical analysis of hip compression loading during
lifting Ergonomics 28429-440 1985 Bibliographic Links [Context Link]
25 Nemeth G J Ekholm and U P Arborelius Hip load moments and muscular activity
during lifting Scand J Rehabil Med 16103-111 1984 Bibliographic Links [Context Link]
26 Nemeth G J Ekholm U P Arborelius K Schlt951gtuldt and K Harms-Ringdahl Hip
joint load and muscular activation during rising exercises Scand J Rehabil Med 1693-102
1984 Bibliographic Links [Context Link]
27 Nisell R and J Ekholm Patellar forces during knee extension Scand J Rehabil Med
1763-74 1985 Bibliographic Links [Context Link]
28 Nisell R and J Ekholm Joint load during the parallel squat in powerlifting and forces of
in vivo bilateral quadriceps tendon rupture Scand J Sports Sci 863-70 1986 [Context
Link]
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Select All Export Selected to PowerPoint
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Link]
30 Palmitier R A K-N An S G Scott and E Y S Chao Kinetic chain exercise in knee
rehabilitation Sports Med 11402-413 1991 Ovid Full Text Bibliographic Links [Context
Link]
31 Weidenhielm L Knee osteoarthrosis aspects of clinical symptoms corrective surgery leg
alignment and knee joint load(Dissertation) Karolinska Institute Stockholm Sweden 1992
[Context Link]
32 Wretenberg P F Yi F Lindberg and U P Arborelius Joint moment of force and
quadriceps muscle activity during squatting exercise Scand J Med Sci Sports 3244-250
1993 Bibliographic Links [Context Link]
33 Zernicke R F J Garhammer and F W Jobe Human patellar-tendon rupture J
Bone Joint Surg Am A-59179-183 1977 [Context Link]
WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
IMAGE GALLERY
Table 1
Figure 1-Weightlifte
Figure 2-Calculation
Figure 3-Individual
Figure 4-Mean maximu
Figure 5-Mean maximu
Figure 6-Schematic d
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Copyright (c) 2000-2014 Ovid Technologies Inc
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Version OvidSP_UI031200116 SourceID 60384
[Context Link]
17 Hammarskjoumlld E K Harms-Ringdahl and J Ekholm Shoulder-arm muscular activity and
reproducibility in carpenters work Clin Biomech 581-87 1990 Bibliographic Links
[Context Link]
18 Hattin H C M R Pierrynowski and K A Ball Effect of load cadence and fatigue on
tibio-femoral joint force during a half squat Med Sci Sports Exerc 5613-618 1989
[Context Link]
19 Lander J F R L Simonton and J K F Giacobbe The effectiveness of weight-belts
during the squat exercise Med Sci Sports Exerc 22117-126 1990 Ovid Full Text
Bibliographic Links [Context Link]
20 Lander J E J R Hundley and R L Simonton The effectiveness of weight-belts
during multiple repetitions of the squat exercise Med Sci Sports Exerc 24603-609 1992
Ovid Full Text Bibliographic Links [Context Link]
21 Lindbeck L and U P Arborelius Inertial effects from single body segments in dynamic
analysis of lifting Ergonomics 4421-433 1991 Bibliographic Links [Context Link]
22 McLaughlin T M C J Dillman and T J Lardner A kinematic model of performance in
the parallel squat by champion powerliftersMed Sci Sports 2128-133 1977 [Context Link]
23 McLaughlin T M T J Lardner and C J Dillman Kinetics of the parallel squat Res Q
2175-189 1978 [Context Link]
24 Nemeth G and J Ekholm A biomechanical analysis of hip compression loading during
lifting Ergonomics 28429-440 1985 Bibliographic Links [Context Link]
25 Nemeth G J Ekholm and U P Arborelius Hip load moments and muscular activity
during lifting Scand J Rehabil Med 16103-111 1984 Bibliographic Links [Context Link]
26 Nemeth G J Ekholm U P Arborelius K Schlt951gtuldt and K Harms-Ringdahl Hip
joint load and muscular activation during rising exercises Scand J Rehabil Med 1693-102
1984 Bibliographic Links [Context Link]
27 Nisell R and J Ekholm Patellar forces during knee extension Scand J Rehabil Med
1763-74 1985 Bibliographic Links [Context Link]
28 Nisell R and J Ekholm Joint load during the parallel squat in powerlifting and forces of
in vivo bilateral quadriceps tendon rupture Scand J Sports Sci 863-70 1986 [Context
Link]
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Select All Export Selected to PowerPoint
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Link]
30 Palmitier R A K-N An S G Scott and E Y S Chao Kinetic chain exercise in knee
rehabilitation Sports Med 11402-413 1991 Ovid Full Text Bibliographic Links [Context
Link]
31 Weidenhielm L Knee osteoarthrosis aspects of clinical symptoms corrective surgery leg
alignment and knee joint load(Dissertation) Karolinska Institute Stockholm Sweden 1992
[Context Link]
32 Wretenberg P F Yi F Lindberg and U P Arborelius Joint moment of force and
quadriceps muscle activity during squatting exercise Scand J Med Sci Sports 3244-250
1993 Bibliographic Links [Context Link]
33 Zernicke R F J Garhammer and F W Jobe Human patellar-tendon rupture J
Bone Joint Surg Am A-59179-183 1977 [Context Link]
WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
IMAGE GALLERY
Table 1
Figure 1-Weightlifte
Figure 2-Calculation
Figure 3-Individual
Figure 4-Mean maximu
Figure 5-Mean maximu
Figure 6-Schematic d
Back to Top
Copyright (c) 2000-2014 Ovid Technologies Inc
Terms of Use Support amp Training About Us Contact Us
Version OvidSP_UI031200116 SourceID 60384
Select All Export Selected to PowerPoint
29 OShea P The parallel squat Natl Strength Condit Assoc J 74-6 1985 [Context
Link]
30 Palmitier R A K-N An S G Scott and E Y S Chao Kinetic chain exercise in knee
rehabilitation Sports Med 11402-413 1991 Ovid Full Text Bibliographic Links [Context
Link]
31 Weidenhielm L Knee osteoarthrosis aspects of clinical symptoms corrective surgery leg
alignment and knee joint load(Dissertation) Karolinska Institute Stockholm Sweden 1992
[Context Link]
32 Wretenberg P F Yi F Lindberg and U P Arborelius Joint moment of force and
quadriceps muscle activity during squatting exercise Scand J Med Sci Sports 3244-250
1993 Bibliographic Links [Context Link]
33 Zernicke R F J Garhammer and F W Jobe Human patellar-tendon rupture J
Bone Joint Surg Am A-59179-183 1977 [Context Link]
WEIGHTLIFTING POWERLIFTING SQUATTING EXERCISE HIP KNEE EMG BIOMECHANICS
IMAGE GALLERY
Table 1
Figure 1-Weightlifte
Figure 2-Calculation
Figure 3-Individual
Figure 4-Mean maximu
Figure 5-Mean maximu
Figure 6-Schematic d
Back to Top
Copyright (c) 2000-2014 Ovid Technologies Inc
Terms of Use Support amp Training About Us Contact Us
Version OvidSP_UI031200116 SourceID 60384