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Screening, progressing, and working around injuries for the squat

This article covers the screening process for the body weight squat. Once the body weight squat pattern is clear the trainer can start to think about adding load to the movement. However, there will be some common problems you will see with the squat. This post will examine those problems and how to troubleshoot them. There is a video below as well if you’d rather just watch that!

The squat, in some form is one of the most widely used exercises in personal training and strength and conditioning. A desirable body weight squat is when the client can reach at least 90 degrees of knee flexion with proper leg symmetry. The inability to do this could be indicative of a number of different factors (Kritz 2009).

 squat screen

When introducing the squat to a new client it is not necessary to try to make a diagnostic evaluation based on lack of mobility or stability in certain joints or hypothesized specific weaknesses. The first thing a trainer should consider is that the client simply does not know how to squat. Once lack of knowledge of how to squat is ruled out the trainer may then want to look at specific strengthening or mobilization techniques along with modification or regression of the exercise.

When evaluating the squat it would be wise for trainers to ask the client to do multiple repetitions. With each rep examine what is happening at each joint. In the squat compensation can show itself in the ankles, knees, hips, lumbar spine, or thoracic spine. The trainer should also examine the client from different angles. Watching the client only from the saggital plane may not allow the trainer to see any medial knee displacement that would be observed in the coronal plane. The bilateral squat is described as flexion of the hip and knee joints until the proximal part of the femur is lower than the distal portion. The knees and hips then extend to their starting position.

The squat is a movement pattern that requires mobility at the ankle, hip, and thoracic spine with stability at the foot, knee, and lumbar spine (Cook). The client may not be able to squat due to a number of reasons including anthropometics, previous injury, lack of coordination, or range of motion and balance (Kritz).

Stiffness in the ankle can restrict dorsiflexion range of motion and may cause the heels to come off the ground which creates compensatory torques increases about the ankles, knees, hips and spine (Kritz). The trainer may also see foot pronation which is an inward roll of the foot. The trainer may also see the feet rotate externally if the client lacks ankle dorsiflexion. Restricted dorsiflexion may be due to tight and/or overactive calf muscles that result in increases in foot pronation, tibial internal rotation and calcaneal eversion (Padua).

Moving up to the knees the trainer may observe medial knee displacement know as valgus collapse or a bowing of the legs known as a varus knee position. Knee valgus is associated an increased risk of ACL injuries, patellofemoral pain, knee osteoarthritis, medial collateral ligament sprains, and knee cartilage and meniscus damage (Padua). Knee valgus is thought to be the result of femoral adduction and internal rotation and tibial aduction and external rotation (Bell).

During the squat the knees should be tracking over the toes rather than inside (valgus) or outside (varus) the toe line. The knees may fail to maintain alignment because of faulty structure and function of the joints and muscles above or below the joint (Kritz). Neuromuscular characteristics associated with knee valgus include decreased gluteal activation or strength, increased hip-adductor activation, and decreased ankle-dorsiflexion range of motion (Padua). The danger in valgus collapse in loaded patterns and sporting activities is that high valgus angles stress the ACL.

In a study by Bell et. al the authors found, contrary to popular belief that weakness of the hip external rotators as well as the gluteus maximus and medius did not seem to be a contributing factor to medial knee displacement. Differences were found in dorsiflexion range of motion but the differences were not statistically significant. The medial knee displacement group did exhibit less plantarflexion strength by 17%. The valgus collapse may be explained by this since the medial gastrocnemius acts as a dynamic knee stabilizer and may prevent knee valgus (Lloyd). The Bell study did state that the role of ankle dorsiflexion should not be discounted in medial knee displacement.

In a study by Padua et. al. on medial knee displacement they discovered that hip adductor, gastrocnemius, and tibialis anterior muscle activation amplitude was greater in the medial knee displacement group. Glute medius and glute maximus muscle activation amplitude was not different. They found that activation of the gastrocnemius was 42% greater in the medial knee displacement ground when compared to the control group. When they added a two inch heel lift to the medial knee displacement group gastrocnemius and tibialis anterior activation was decreased and there was an associated decrease in medial knee movement.

A heel lift is often used to determine if the medial knee displacement is caused by lower leg imbalances or hip imbalances or weakness. It is hypothesized that if medial knee displacement is not present after the inclusion of the heel lift that the lower body musculature was causing the dysfunction. If the aberrant knee movement is still present after using a heel lift than it can be assumed that the hip musculature was causing the problem. “Correction of MKD when using a 5.1-cm (2-in) heel lift is theorized to occur by increasing ankle plantarflexion and thereby decrease the tension within the lateral ankle musculature and restore the normal length-tension relationship of the medial gastrocnemius, anterior tibialis, and posterior tibialis so that they may better control knee valgus and foot pronation” (Bell).

In a review on the overhead squat by Christopher Hirth, the author states that when the client experiences valgus collapse the biceps femoris, tensor fascia latae, lateral gastrocnemius, and vastus lateralis may be overactive whereas the medial gastrocnemius, medial hamstring, gluteus maximus, and vastus medialis may be underactive (Hirth).

Aside from medial knee displacement the trainer may notice that the client initiates the squat with knee flexion but lacks the hip flexion to go along with it. This anterior motion of the knees increases shear and compressive forces at the knee (Fry). In this pattern the trainer may also notice a squat pattern where the knees move past the toes. In a study by Escamilla et. al they identified different squat stances for master level powerlifters. In a narrow squat stance they discovered that there was on average 4-6 cm greater forward knee movement when compared to the medium or wide stance squat (Escamilla). They also stated that greater forward knee movements during the squat increase shear forces at the knee. This squat pattern isn’t inherently dangerous, Olympic weight lifters squat with their knees over their toes, but due to the shear forces it is recommended to practice a squat pattern with the knees not going over the toes. This may indicate a quadriceps dominance pattern over the hip extensors. However, the trainer shouldn’t be concerned with keeping the shins completely vertical, the forward knee motion is necessary to some degree, to complete the squat pattern (Kritz).


The hip is a joint that needs mobility in the squat pattern (Cook). It has been postulated that if the client lacks hip mobility the lumbar spine will flex to compensate for the lack of range of motion (Kritz). Lumbar flexion is typically addressed if it occurs before the client reaches parallel in the squat. Before attempting to address any one specific issue that the client is experiencing to cause the lumbar flexion the trainer should focus on teaching the squat. The trainer can use a high box squat to identify the point where form breaks down. If form breaks down on a seventeen inch box work with the available range of motion while grooving the pattern.

Work down to a sixteen inch box and then work towards having the client hit parallel. Besides lack of hip mobility, anecdotal evidence suggests that lumbar flexion may also be caused by shortened hamstrings or a lack of core strength.

The squat pattern should not be loaded if the trainer observes that the client has the inability to squat without flexing at their lumbar spine. The inability to stabilize the lumbar spine and/or slightly extend at the thoracic spine during the loaded squat increases compressive and shear forces of the lumbar spine (Kritz).

One final addition to the squat screen is the overhead squat screen. This screen adds an upper body component to the squat which addresses shoulder and thoracic spine function. The trainer gives the client a dowel to hold overhead with the arms full extended using a snatch style width. It is desirable for the bar to not drift away from the body’s center of gravity. If the arms do fall forward it could be indicative of certain overactive muscles including the latissimus dorsi, pectoralis major and minor, and coracobrachialis. It may also be indicative of underactive muscles such as the middle trapezius, lower trapezius, rhomboids, posterior deltoids, or the rotator cuff (Hirth).

Attached in PDF form is a flow chart on trouble shooting the squat

squat flow chart pdf

I wasn’t able to embedd the second video on progressions and working around injuries so you can watch it here 


  1. Bell D. R., Padua D. A., Clark M. A. Muscle strength and flexibility characteristics of people displaying excessive medial knee displacement. Arch Phys. Med. Rehabil. 89: 1323-1328, 2008
  2. Cook G. Athletic Body in Balance. Champaign, IL: Human Kinetics, 2003
  3. Escamilla R. F., Fleisig G. S., Lowry T. M., Barrentine S. W., Andrews J. R. A three-dimensional biomechanical analysis of the squat during varying stance widths. Journal of the American College of Sports Medicine. 984-998, 2001
  4. Fry A. C., Smith J.C., Schilling B. K. Effect of knee position on hip and knee torques during the barbell squat. Journal of Strength and Conditioning Research. 17: 629-633, 2003
  5. Hirth CJ. Clinical movement analysis to identify muscle imbalances and guide exercise. Athl Ther Today 12: 10-14, 2007.
  6. Kritz M., Cronin J., Hume P. The bodyweight squat: A movement screen for the squat pattern. Strength and Conditioning Journal. 31: 76-85, 2009
  7. Lloyd DG, Buchanan TS. Strategies of muscular support of varus and valgus isometric loads at the human knee. J Biomech 2001;34:1257-67.
  8. Padua D. A., Bell D. R., Clark M. A. Neuromuscular characteristics of individuals displaying excessive medial knee displacement. Journal of Athletic Training. 47 (5) 525-536



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