acl injury prevention in the female athlete: who, what, and how? jill thein-nissenbaum, pt, dsc,...
TRANSCRIPT
ACL Injury Prevention in the Female Athlete: WHO, WHAT , and HOW?
Jill Thein-Nissenbaum, PT, DSc, SCS, ATC Assistant Professor, UW-Madison
Staff PT, Badger [email protected]
Objectives • WHO: determine the age at which ACL prevention programs
can be successfully implemented
• WHAT: Identify the content of a successful ACL prevention program, including frequency and duration
• HOW: identify the best verbal and visual motor learning strategies to deliver the information
Brief History • Injury to the anterior cruciate ligament (ACL)
occurs 4-6x more frequently in female athletes vs. males in similar sports
• ~125,000 ACL reconstruction surgeries performed in the US/year
• >10,000 articles related to ACL on Medline
• Do ACL prevention programs work?
Myer, Am J Sports Med, 2013
The Good News • Strong evidence for a significant, positive effect of prevention
programs; ~62% reduction (meta-analysis with 8 studies)
• Training interventions have a preventive effect on ACL tears (systematic review with 9 studies)
• ACL tear reduction by approximately 50%, lots of variance (meta-analysis with 14 studies, n =27,000)
Sadoghi, JBJS, 2012
Stojanovic, Res Sports Med, 2012
Gagnier, Am J Sports Med, 2013
ACL reduction expectation • On average, intervention programs can drop risk by about 50%
(risk is cut approximately in half) which is a huge effect on relative risk provided by neuromuscular training
Hewett, IJSPT, 2010
The Challenge
• No conclusive evidence supporting any one specific type of intervention
• Various types of neuromuscular and educational interventions
• The concern: At the end of the day, individuals who have torn their ACL-regardless of how it is managed-have knee OA at a rate 10x those without an ACL injury
Stojanovic, Res Sports Med, 2012
Gagnier, Am J Sports Med, 2013
Sadoghi, JBJS, 2012
Objectives • WHO: determine the age at which ACL prevention programs
can be successfully implemented
• WHAT: Identify the contents of a successful ACL prevention program, including frequency and duration
• HOW: identify the best verbal and visual motor learning strategies to deliver the information
The Active Youth • Youth sport participation has significantly increased over the
past decade and children are starting sport at an earlier age
• The 2008 Physical Activity Guidelines for Americans recommends youth (ages 6 to 17) include ‘‘muscle and bone strengthening’’ exercises in their exercise regimens.
• When are children capable of understanding the fundamentals of movement and performance?
The Window of Opportunity • Meta-analysis of timing of initiation of prevention programs
on ACL reduction (14 clinical trials)• # ACL injuries reported • NMT intervention that aimed at decreasing ACL tears • A control group • Prospective controlled trial study design • Females
• RESULTS: Significantly greater knee injury reduction in female athletes in prevention programs vs. controls (OR: 0.54; 95% CI: 0.35, 0.83)
Myer, Am J Sports Med, 2013
The Window of Opportunity • Reduction rankings: • #1:Mid-teens (14-18y), 72% reduction rate • #2: Late teens (18-20y), 52% reduction rate • #3: Early adults (>20y), 16% reduction rate
• May be optimal to implement NMTprograms during pre or early adolescence.
Myer, Am J Sports Med, 2013
How Young is TOO Young?
• Compare the effects of traditional and age-specific pediatric ACL prevention programs on lower extremity biomechanics during a cutting task in youth athletes
• 65 youth soccer athletes (38 boys, 27 girls) age 9-11, participated in the 9-week program (12-14 minutes, 2-3x/week)
• Teams were clustered: (1) pediatric injury prevention program, (2) a traditional injury prevention program, or (3) a control group and performed the program as part of warm-up
DiStefano, Am J Sports Med, 2011
How Young is TOO Young?
• The Pediatric Program:• High repetitions of BW strengthening exercises, gradual increase
in training sessions per week. Slowly implemented plyometric exercises
• Provided constant verbal feedback and cues such as ‘‘bend your knees’’ and ‘‘keep your toes straight ahead’’
• Progressions included a lot of variety, which may improve motivation and compliance
DiStefano, Am J Sports Med, 2011
How Young is TOO Young?• Results:
• The Pediatric Group: lower peak internal knee rotation at initial contact of a cutting maneuver, but no sagittal or frontal plane changes were observed
• The Traditional Training Group: no changes
• These findings suggest limited effectiveness of both programs for athletes younger than 12 years of age in terms of biomechanics during a cutting task.
DiStefano, Am J Sports Med, 2011
Objectives • WHO: determine the age at which ACL
prevention programs can be successfully implemented
• WHAT: Identify the contents of a successful ACL prevention program, including frequency and duration
• HOW: identify the best verbal and visual motor learning strategies to deliver the information
Meta-analyses of prevention programs
• No conclusive evidence supporting any one type of intervention• No superiority of balance board exercises, new protocols over
older ones
• Moderate evidence to support the use of stretching, proprioception, strength, plyometric and agility drills with additional verbal and/or visual feedback on proper landing technique
• Unable to determine which program components were most or least effective.
Sadoghi, JBJS, 2012
Gagnier, Am J Sports Med, 2013
Stojanovic, Res Sports Med, 2012
PEP Program • Prevent injury and Enhance Performance (PEP) Program• Warm-up, stretching, strengthening, plyometrics, and sport
specific agility exercises for soccer • Performed on the field before practice; no extra specialized
equipment• 19 components • ~20 minutes• 3x/week
Gilchrist, Am J Sports Med, 2008
PEP in 14-18 yo females • >1000 female athletes in the intervention group
(education, stretching, strengthening, plyometrics, and sports-specific agility drills)
• >1900 female athletes in the control group (traditional warm-up)
• Year 1: 88% decrease in ACL injury rate in the intervention group as compared to the control group
• Year 2: 74% reduction
Mandelbaum, Am J Sports Med, 2005
PEP in NCAA DI females • 61 female soccer teams consisting of 1435 athletes
(852 control athletes; 583 intervention)
• ACL rate in the intervention group was 1.7 x less than in the control athletes (41% decrease)
• Intervention athletes with a history of ACL injury were significantly less likely to suffer another ACL tear compared to controls with previous ACL tears
• Santa Monica Sports Medicine Foundation and the PEP (Prevent Injury and Enhance Performance) Program http://smsmf.org/smsf-programs/pep-program
Gilchrist, Am J Sports Med, 2008
11+• 125 soccer clubs in Norway followed for
one league season (eight months)
• Participants were 1892 female players aged 13-17
• Intervention: Comprehensive warm-up program to improve strength, awareness, and neuromuscular control during static and dynamic movements
Soligard, BMJ, 2008
Soligard, BMJ, 2008
11+• In the intervention group, there was a significantly lower risk
of severe injuries, overuse injuries, and injuries overall
Soligard, BMJ, 2008
HarmoKnee Program • Goals: • Increase awareness of injury risk • To provide a structured warm-up program• To provide strengthening exercises that produces less strain to
the knee joint
• Swedish female soccer players age 13-19
Kiani, Arch Intern Med, 2012
HarmoKnee Program
• The training program: implemented at a practice session; athletes and coaches were trained in the correct way to perform and teach the exercises
• 5 parts: warm-up, muscle activation, balance, strength, and core stability• Integrated into the regular soccer practice sessions with no
additional equipment
Kiani, Arch Intern Med, 2012
HarmoKnee Program • 94% of intervention teams reported >75% compliance
• Control group: 13 knee injuries (5 ACL tears)
• Intervention group: 3 knee injuries (NO ACL tears)
• A 77% reduction in knee injury incidence and a 90% reduction in noncontact knee injury incidence
Kiani, Arch Intern Med, 2012
Programs Summarized
• PEP (RR 0.18, CI 0.08 to 0.42) 82% reduction • The PEP also significantly reduced the risk of recurrence in those
with previous non-contact ACL injuries (P = 0.046)
• HarmoKnee (RR 0.22, CI 0.06 to 0.76) 78% reduction
• The 11+ program (RR 0.48, CI 0.32 to 0.72) 52% reduction
Herman, BMC Medicine, 2012
Rankings: Systematic Review • Effectiveness of neuromuscular warm-ups • PEP: most effective in reducing ACL injuries
• 11+ and HarmoKnee: significant reduction of knee injury risk
Herman, BMC Med, 2012
ACL prevention programs are successful• Especially adolescent female soccer players
• Mostly done as warm-up
• Little to no equipment
• Some strength training, some plyometric activity and some balance
Frequency
• Agreement that an ACL prevention program should include at least 10 minutes of exercises 3x/week, as a bare minimum
****Most studies report performing 15-20 minutes of activity
• Determined that the estimated protective effect was relatively stronger in studies involving more training time each week and in those studies with better compliance
Sadoghi, JBJS, 2012
Gagnier, Am J Sports Med, 2013
Duration • Programs should begin prior to season, at least
6 weeks pre-season ***Most studies recommend 8 or more weeks in duration to allow sufficient neuromuscular changes and performance training effects
• Ideally, the program can be continued throughout the season, at a lower frequency or duration (i.e.-cut the warm-up to 10-15 minutes if necessary)
Sadoghi, JBJS, 2012
Voskanian, Curr Rev Musculoskelet Med, 2013
Numbers Needed to Treat• Determine overall ACL injury risk in female athletes through
relative risk reduction (RRR) and numbers needed to treat (NNT) • 12 studies, Systematic review (ish)• To prevent one ACL in one competitive season: ~108
• PEP: (82% reduction): 70 • HarmoKnee: (78% reduction): 72 • The 11+ program: (52% reduction): 28 (?)
Sugimoto, BR J Sports Med, 2012
Herman, BMC Medicine, 2012
Components of an Injury Prevention Program • Muscle strengthening
• Plyometrics
• Neuromuscular training / control / balance
• Education and feedback regarding body mechanics and proper landing patterns in a dynamic atmosphere (HOW)
Voskanian, Curr Rev Musculoskelet Med , 2013
Weeks 1-3Impact, 2-
footed, light
plyometrics
Soft landing techniques (2-footed),
easy, lower level balance
Fundamental skills, such as athletic stance, bias towards isolated strength training for the glute med, glute max, quadriceps and
hamstring and core
Weeks 4-6Sagittal plane plyometrics get bigger, start
introducing single leg impact and light plyometrics
Impact and landing still stressed, add frontal and transverse planes movements, progress
balance
Combined movements that incorporate multiple muscles, start sagittal, then progress to frontal
and transverse planes, less isolated strengthening
Weeks 7+
Plyometrics become multiplanar, more single leg, alternating legs
Higher level balance, EC, higher level core
and strength with planned / unplanned
perturbations
Strength Training
Objectives • WHO: determine the age at which ACL prevention programs
can be successfully implemented
• WHAT: Identify the contents of a successful ACL prevention program, including frequency and duration
• HOW: identify the best verbal and visual motor learning strategies to deliver the information
Motor Learning • Prevention programs most likely address the impairments that
need to be addressed.
• Laboratory data show improvements in jumping and landing techniques.
• However, ACL tears are still happening at a fairly high rate.
• Is something lost in transition from conscious awareness during training / rehabilitation sessions to automatic movements during practice / competition?
3 Stages of Motor Learning• Cognitive: conscious attempt to determine what exactly needs
to be done, step by step. This requires considerable attentional capacity.
• Associative: basic movement pattern is acquired; the movement outcome is more reliable, movements are more consistent, automatic, and economical.
• Autonomous: fluent and seemingly effortless motions that are accurate, consistent, and efficient. The skill is performed largely automatically and requires little or no attention.
Benjaminse, JOSPT, 2015
Explicit Motor Learning • Explicit motor learning: acquiring motor skills with an internal
focus on their movement pattern
• Focus is on HOW the individual is moving • “Land with your knees flexed” • “Land with your feet shoulder-width apart”• “Focus on the quality of movement” • “Land in the knee-over-toe position”
• http://youtu.be/ctFmp_TQqkI
Benjaminse, Knee Surg Sports Traumatol Arthrosc , 2011
Explicit Motor Learning • Less resilient under psychological and physiological fatigue
• Less durable when a fast response is required
• Less efficient, attention demanding, and slow
• May be affected to by an individual’s intelligence
• Extensively repeating the ideal movement that is explained and demonstrated might be too ‘cognitive’.
Benjaminse, JOSPT, 2015
Explicit Motor Learning
• Results in an increase of co-contraction, resulting in a “stiff” landing and recruiting unnecessary motor units
• In a lab setting, using explicit cues, jump forces and landing techniques immediately improved; one week later, retention was POOR
• Clinicians provide explicit feedback 95% of the time.
Lohse, Acta Psychologica, 2012
Durham, Physiother Research Inter, 2009
Prapavessis, JOSPT, 2003
Implicit Motor Learning • Implicit motor learning: acquisition of a motor skill
without the concurrent acquisition about the performance of a skill
• Implicit learning has an external focus, directed at the outcome of movements (end result, such as “Imagine sitting down on a chair when landing”)
Benjaminse, Knee Surg Sports Traumatol Arthrosc , 2011
Implicit Motor Learning • Implicit learning includes observation and imitation of a drill
or activity; this observation plays an important role
• Copying of observed body movements
Implicit Motor Learning • Shortens the cognitive and associative stages of motor
learning
• Enhances skill acquisition more efficiently and increases the potential to transfer to sport with its complex motor skills
• Example: with jumping and landing, implicit learning results in more efficient EMG activity, greater knee flexion, and reduced vertical ground reaction forces
Benjaminse, Phys Ther in Sport, 2014
Benjaminse, JOSPT, 2015
Research Supports Implicit Learning• Jump height with Vertec was better with
instruction to concentrate on the rungs of the Vertec vs. the tips of their fingers
• Instructing subjects to jump towards a target resulted in superior jump distance vs. instructing subjects to extend their knees as rapidly as possible
• Land more softly by listening to the sound of the landing resulted in significant lower GRF compared to the control group.
Bredin, Applied Phys Nutr Metab, 2013
Wu, J Strength Cond Res, 2012
McNair, Br J Sports Med, 2000
How does Implicit Learning work?
• The premotor cortex has a role in preparation and execution of movements; utilization of the premotor cortex may reduce brain resources needed for movement control, allowing more “free space” to focus on other game factors (i.e., other athletes, field conditions, and position of the ball).
Benjaminse, JOSPT, 2015
Implicit Learning and Mirror Neurons
• Mirror neurons are housed in the premotor / motor areas. They fire both when an action is performed AND when a similar or identical action is passively observed
• A KEY aspect of mirror neurons is their ability to link visual and motor properties.
Benjaminse, Knee Surg Sports Traumatol Arthrosc , 2011
Mirror Neurons • Mirror neurons map observed movements onto a motor
program and your brain develops a template of the movement
• This motor map of the observed action corresponds to that which is spontaneously generated during active action.
Benjaminse, Knee Surg Sports Traumatol Arthrosc , 2011
Rizzolatti, Annu Rev Neurosci, 2004
Mirror neurons were discovered in the 1990s, when researchers found neurons in the brains of macaque monkeys that fired both when the monkeys grabbed an object and also when the monkeys watched another primate grab the same object. (Rizzolatti)
Mirror Neurons • Amount of mirror neuron activation correlates positively when
the athletes are already proficient in performing that skill
• Stronger mirror neuron activation is found when observing the same gender
Benjaminse, Knee Surg Sports Traumatol Arthrosc , 2011
SO…….• Is the solution to injury prevention hidden in the brains of the
subjects themselves?
•Maybe it IS “all in their head” (mirror neurons) AND what we say (external focus / implicit learning)!!!
Benjaminse, Knee Surg Sports Traumatol Arthrosc , 2011
Example: Learning and Single Leg Hop
• Implicit learning vs. explicit learning on single leg hop jump distance and knee kinematics in patients after ACLR. (N=16)
• Internal focus (explicit learning): ‘‘Jump as far as you can. While you are jumping, I want you to think about extending your knees as rapidly as possible.’’
• External focus (implicit learning): ‘‘Jump as far as you can. While you are jumping, I want you to think about pushing yourself off as hard as possible from the floor.”
• Measured numerous variables related to landing
Gokeler, PT in Sport, 2014
Example: Learning and Single Leg Hop
• External focus (implicit learning) group had: • larger knee flexion angles at initial contact• greater peak knee flexion• greater total ROM
• Concluded: hopped farther with less valgus, more knee flexion with external focus (implicit learning)
Gokeler, PT in Sport, 2014
Example: Plyometrics • External focus (implicit learning) resulted in higher jump-and-
reach heights, greater force and more knee flexion vs. using an internal focus of attention
• Focusing on an external object, such as a Vertec or hanging ball, is considered positive feedback, which increases motivation
Makaruk, J Sports Med Phys Fitness, 2012
Wulf, J Mot Behav, 2009
Implicit Learning Method: Dyad Training
• Fancy way of saying “Watch your partner”
• A visual example (dyad) of a teammate performing the task can increase the effectiveness of feedback and training methods without an excessive cost of time
• A combination of observation and practice can result in more effective and cumulative learning than either type alone.
Example: Dyad Training• Balance on a stabilometer in healthy college students; goal
was to keep the platform horizontal for as long as possible during a 90-second trial. Success was the time horizontal.
• RESULTS: Alternating between practice forms (physical, observational, and dialog with a partner) was more effective in retention than individual, isolated practice.
• BONUS: The benefits of dyad training transfer to situations where participants have to perform the movement individually.
Shea, J Mot Behav, 1999
Benefits of Dyad Training • Athletes may set goals at a higher level of difficulty, after
seeing what their peer can do. (Motivational)
• Training with a partner and sharing learning strategies might increase the athlete’s feeling of responsibility and they may take ownership of the task.
Video Feedback • Imitation activates the mirror neurons, which link visual input
with motor output.
• Can observe skilled or unskilled athlete. (Observing lower skill can positively affect learning.)• Viewing either a correct model or learning model was equally
effective in learning correct squat form.
• Observation of lower skill level helps identify movement deficits and assists the athlete to develop strategies to correct their own errors.• Ubersense, Dartfish, Coach’s Eye, or BaM Video Delay
Benjaminse, JOSPT, 2015
McCullagh, Exerc Sport Sci Rev, 1989
Frequency of Feedback • A high frequency of feedback that promotes an external focus
(implicit learning) is superior to a low feedback frequency in athletes.
• In contrast, a high frequency of feedback that promotes an internal focus (explicit learning), was shown to be detrimental to learning.
• Research supports giving the athlete some control over frequency of feedback in a practice session (may enhance motor learning)
• Athletes are fairly good at self-assessingChiviacowsky, Front Psychol, 2012
Summary: Motor Learning
• The transition from conscious awareness to automatic movements involves complicated motor learning; this might not fit in explicit learning strategies
• An external focus (implicit learning) may get an athlete to the autonomous stage of motor control faster and improve performance.• A focus on the movement outcome promotes the
utilization of unconscious or automatic processes
Benjaminse, Knee Surg Sports Traumatol Arthrosc , 2011
Cognitive
Associative
Autonomous
Implicit Learning Applications• The ability for individuals to view themselves performing
correctly or making mistakes and responding to the corrections is of greater value to individuals than is viewing an expert model performing the task correctly
• Learning is a problem-solving process; the more involved the individual is in analyzing his or her own performance, the greater the learning value
Benjaminse, Knee Surg Sports Traumatol Arthrosc , 2011
Implicit Learning Applications• Provide opportunities for the athlete to watch / observe the
expected movement patterns• Team Practice!! (Re-think what the athlete is doing during team
practice, perhaps they should be intently WATCHING!)
• Provide opportunities for athlete to watch themselves, self-assess, and re-try the movement • Video works well (iPad, phone)• Mirrors
• Watch your words! • Focus is on the GOAL, not the process. “Jump out as far as you
can towards the cone”
Put it all together: 3 objectives
Recommendations: WHO • Although there are limitations, implementation of an ACL
injury prevention is advisable; No study has demonstrated any significant detrimental effects
• Age: at or prior to the onset of puberty (12 ± 1, start by 14, and not < 10)
• Consider pre-season risk assessment by a qualified healthcare provider to identify those at greatest risk of large benefit (I would argue to avoid singling out individuals)
Dai, Res Sports Med, 2012
Key Elements: WHAT
• Duration: 6-8 weeks prior to the sport and during season
• Frequency: 3x/week pre-season and 2x/week mid-season
• Length: at least 15 minutes
Voskanian, Curr Rev Musculoskelet Med, 2013
Recommendations: WHAT • Dynamic warm-up is a strong option; can use throughout pre-
and in-season practice
• Strengthening exercises and FUNDAMENTAL MOVEMENT PATTERNS (with body weight) should be considered with younger athletes in particular
• Add impact, landing and plyometrics as a progression
• Balance training has also shown some positive results, but it may require additional equipment
Dai, Res Sports Med, 2012
Recommendations: HOW• Challenges with cueing and feedback! • Implicit motor learning with an external focus is best
• Delivery: Demonstration (does not have to be expert). Consider partner drills (watch each other), use of mirror or videotaping.
• Use cues like “land quietly on your feet”, “sit back as if you were sitting in a chair”, “jump towards the farthest cone”
Dai, Res Sports Med, 2012
Thanks!
I hear and I forgetI see and I rememberI do and I
understand~Confucius