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