Upload
xceelent
View
289
Download
10
Embed Size (px)
Citation preview
Is the exercise helpful? Does it do harm?
The Squat Exercise and the Functional Integrity of the Knee
Joint
Trevor Cottrell, PhD
Athletic Therapy Program Coordinator, Sheridan College
Brief History of the Squat
• Weightlifters up until the mid 1950’s largely used the “split” to lift heavy wts– the squat was used but as a
supplement for leg strength
• “Odd lifts” (now power lifts) became popular in the 1950’s. The squat was a part of this activity.
What is a squat?
Or maybe it looks like this…
Or this…
Where else do we squat?
Why do we train squats?
Why do we train squats?
Why all of the controversy?
Stop that! You’re going tohurt your knees.
Objectives:
1. Identify potential locations of knee injury during squats
2. Evaluate research studying the safety of the squat
3. Examine the benefits of squatting4. Coach appropriate techniques for squat
progression.
The knee and its supporting structures
MCL – provides stability to the inner part of the knee
LCL – provides stability to the outer part of the knee
The knee and its supporting structures
ACL – limits rotation and forward movement of patella
PCL – limits backward movement of the patella
The knee and its supporting structures
Menisci – shock absorbers, stabilizers
Articular cartilage – shock absorbers, smooth movement
Common Knee Injuries and Problems
1. Arthritis2. Cartilage injuries and disorders3. Injuries to the meniscus4. Ligament injuries5. Tendon injuries and disorders
The Controversy BeginsKlein, K.K. “The deep squat exercise as utilized in weight training for athletes and its effect on the ligaments of the knee.” J. Assoc. Phys. Ment. Rehabil. 15:6-11, 1961
Hypothesis:– the deep squat exercise will stretch ligaments of the knee
and cause knee instabilityMethods:
–– 128 experienced weightlifters who did full squats and 386 128 experienced weightlifters who did full squats and 386 subjects who did not compete in weightlifting nor did full subjects who did not compete in weightlifting nor did full squatting.squatting.
–– The study used a device, which Klein had built, to measure The study used a device, which Klein had built, to measure the amount of medial or lateral give in the kneethe amount of medial or lateral give in the knee
“Squats have a debilitative effect on the ligament structures of the knee…”
Results:• Greater MCL and LCL instability
in weightlifters when compared to controls
Conclusions:• Deep squats will cause increased
instability of the knee• Parallel squats should be used in
place of deep squats
The Klein Fallout
• Highlites of the study were published widely in lay-journals
• Thousands of coaches who were suspicious of weights felt vindicated
• General acceptance in the medical community of Klein’s data
• U.S. Marine Corps recommended the removal of squats from their PFT program
Assumption #1: Knee laxity predicts injury
Nicholas, J. Sports Med (1975): • Based on five subjective mobility tests
demonstrated a likelihood of knee ligament rupture with increased looseness in NFL players.
Kalenak and Morehouse, JAMA (1975): • Knee ligament injuries the same in loose and
tight knee joints using objective measures of the knee
Assumption #2: Klein’s tests are reliableKarpovich et al, Teor Praxe tel Vvch (1970):• 10 week program of deep squats did not affect the stability of the
kneeMeyers, Research Quarterly (1971):• using Klein objective device did not find differences in laxity of
the knee Chandler et al, MSSE (1989)• 8 week full squat program did not result in increased instabilitySteiner et al, Amer J Sports Med (1986)• No increased laxity in powerlifters• Increased laxity in basketball players and runners
“ It appears that repetitive physiologic stresses at a high strain rate produce significant ligamentous laxity, while a relatively few large stresses at a low strain rate do not.”
Klein Rebuttal Summary
• Klein’s findings were not valid, accurate or reliable
• Klein’s findings have been handed down through generations of coaches, doctors, PE instructors and everyday people
• Once something is in print, no matter how inaccurate it may be, it can take years to remove the damage that it may cause
So are squats hard on the knees?
Posterior Shear
Anterior Shear
Compression
Shear and Compression Highlites1. Anterior and posterior shear forces increase with depth of
squats but are within tolerable limits2. Shear and compressive forces on the knee increase with speed
of descent and load3. Shear and compressive forces are reduced in experienced
lifters4. Shear and compressive forces increase with fatigue5. Increased compressive forces that occur with increased
loading result in decreased shear forces6. Ligament injuries are rare with squatting
Escamilla et al. (2000) Biomechanics of powerlifting and weightlifting exercises, Exercise and Sports Sciences, WE Garrett and DT Kirkendall (Ed.), LippincottWilliams and Wilkins.
Arthritis and Chrondomalacia?• No difference in degenerative
changes of the knee found between weightlifters and controls
• Less symptomatic arthritis in retired weightlifters
• No chondromalacia signs or symptoms in 80 weightlifters studied
• Low incidence of arthritis in those who load the knee joint through full ROM
Use it or lose it
Greatest concern = patellar tendonitis
• Quadriceps tendon and patellar tendon (ligament) are very susceptible to overuse injuries during prolonged squatting
• Too much load, too many reps, too soon
Squat ConclusionsSquats, when performed correctly …1. are safe2. may prevent injury3. are an effective rehabilitation tool4. can enhance athletic performance5. can enhance muscle strength and
power6. can strengthen connective tissue,
bones, ligaments and tendons7. has transferability to sport
Chandler and Stone (1991) The squat exercise in athletic conditioning: a review of the literature. NSCA J, 13(5), 52-58.
Squat Techniques• Half Squats
– Knee and Hip flexes to 60 degrees
• Parallel Squats– Top of thigh stops when
parallel to floor
• Full Squats– Top of thigh goes below
parallel
• Olympic Squats– Maximum knee flexion -
“rock bottom squats”
• High bar squats– Bar high on traps, greater load
on knees
• Low bar squats– Bar low on traps, greater load
on hips
• Front squats– Bar rests on anterior deltoid,
greater load on knee
4-Level Squatting Progression
1/ Box step ups2/ Supported squats3/ Free-hand squats4/ Barbell squats
Level 1/ Box Step-ups
Secondary progressions:1. Increase box height
Coaching tips– Don’t push off back leg– Don’t lean forward
Start Finish
6” box
12” box
Level 2/ Supported Squats
Secondary progressions:1. High ball/chair2. Low ball/chair3. Single hand support
Coaching tips– Set foot position– Keep back flat– Push hips back– Weight towards the heals
Start/Finish
Level 3/ Freehand Squats
Secondary progressions:1. Hands in front2. Hands overhead
Coaching tips– Sitting on a cold toilet– Lift chest high– Exhale on rising
Start/Finish
Level 4/ Barbell SquatsSecondary progression
1. Add load2. Front squats
Coaching tips– Squeezing traps– Bring elbows back – Keep head up
Start/Finish
Correct bar placement
Golden Rule
Advancement through the levels can only occur by sequential mastery of each level.
Take-Home Messages1. Negative attitudes towards squats are the result of
generations of misinformation and meathead approaches to teaching squat technique
2. Squats are a low-risk exercise with significant health and performance benefits
3. The greatest injury risk with squats occurs from overuse
4. By applying the 4-level method of teaching squat progressions, anyone can learn how to squat safely and effectively