BY DAVID CRUZ, DC, CSCS, FMS, SFMA
The ability to perform a squat or partial squat is an essential primal movement in life we must all be able to do, whether you are 8 or 80 years old. When we think of a squat, most of us associate the move with weight training or a specific sport activity. However, we all perform variations of a squat everyday with activities of daily living ranging from lifting a box to picking up a child or sitting down in a chair. Our ability to do this in a safe and correct manner can be the difference between injury and living a healthy, pain free life.
When done properly, the squat is a safe and effective exercise that can be used for strengthening the entire body. It is estimated that correctly performing a squat requires over 200 upper and lower body muscles to work synergistically. (17) Together, both the upper and lower body must properly work in unison to move through triple flexion and extension of the hip, knee and ankle. This exercise can also be used from rehabilitation to the sport-specific setting by simply changing the range of motion. For instance, in the rehabilitation setting, if quadriceps enhancement is the goal, then keeping the squat to less than 90 degrees is desirable since moving past this range of motion has limited benefit. (1) However, if the intent is to increase hip extensor strength, then increasing the squat depth would be beneficial. (2)
Performing a squat assessment can provide valuable information about a client and potentially reduce their risk of injury. In addition to musculature stability and postural control, dysfunctional movement patterns can also be identified. The inability to perform a squat can be a predictor of a low back or ACL injury. (2, 3, 4) In this article each body region will be discussed along with common movement faults to be aware of. Part 2 will discuss intervention strategies to correct these dysfunctions.
PERFORMING A SQUAT ASSESSMENT
Ask your client to wear shorts and a short sleeve shirt for the assessment. This will make it easier to identify faulty movement patterns. Position the client so that you can observe them from the front and side, as well as being able to observe any rotational movements in the transverse plane.
To perform a squat assessment, begin by instructing the client to stand with their feet shoulder width apart (inside of their feet aligned with the outside of their shoulders). Feet should be straight forward and arms straight above head or with hands gently behind their ears (Figure 1). This position retracts their shoulder blades and activates the upper back musculature providing stability. Their head should be in alignment with their shoulders and eyes gazing straight forward.
Instruct them to descend as far as comfortably allowed while keeping their heels on the ground and pushing the hips back as if sitting in a chair (Figure 2). The tempo should be 2-3 seconds on the way down. Do not attempt to cue them on improper movements you initially see. Have them repeat the squat 3 to 5 times. (2, 5, 6)
Forward head posture has been associated with neck pain, shoulder pain, and temporomandibular joint dysfunction, therefore it is important to assess (Figure 3). (7, 8) Assess from the lateral (side) view watching for anterior head carriage or excessive extension of the neck. From the anterior and posterior view the head should remain in midline and not move side to side. (5, 6)
Eye gaze is also important to monitor as it indicates ones ability to disassociate eye from head movement. As they perform the squat, eye gaze should remain straightforward and not move upward with any head tilt. (5)
UPPER BACK AND SCAPULAR POSITION
Hyperkyphosis or excessive rounding of the upper back has been associated with forward head posture as well as limiting cervical range of motion. (9) Therefore it is important to maintain proper upper back and scapular position. When performing the squat assessment a slightly extended thoracic spine position is recommended to maintain a chest up position (Figure 4). This will also allow the scapula to be retracted. Any rounding of the shoulders and scapula protraction similar to upper cross syndrome should be quickly identifiable. (5, 6)
LOW BACK POSITION
Maintaining a neutral low back position with a slight lordosis is essential to proper and safe motion (Figure 5). Intravertebral disc pressure increases as lumbar lordosis is lost, putting one at risk for injury. (10, 11, 12) Therefore maintaining a lordosis throughout the squat movement is essential. It also allows for proper abdominal bracing necessary to maintain the intra abdominal pressure for proper support. (13)
Pelvic rotation and tilting should be assessed as this could be due to compensation for the low back or hip musculature. Monitor the level of the hips in relationship to the floor. If the hips lack mobility then this may be seen with excessive thoracic forward lean as the body attempts to compensate. Proper pelvic alignment also allows the muscles of the lumbar spine, erector spinae, quadratus lumborum and oblique muscles to function optimally providing support to the lumbar spine reducing the risk of injury. (5)
KNEE TOE ALIGNMENT
ACL injuries occur at a four to six fold greater incidence in females than males and have been associated with increased knee valgus angles. (14, 15) Therefore assessing the knee and toe alignment from the anterior and posterior view is essential (Figure 7). As the client squats down pay close attention and note if the outside of their knee crosses their medial malleolus. (5) This movement dysfunction may be the result of hip muscular weakness, an ankle dorsiflexion problem or over pronation.
There is a general consensus among fitness professionals that increased tibial translation allowing the knees to glide past the toes is harmful and should be avoided. Although knee torque increases as tibial translation occurs, there is no evidence to support ones risk of injury is increased (Figure 8). (5) Conversely, if tibial translation is limited, an increase in trunk anterior lean may occur in order to compensate. This is supported by Fry and colleagues who demonstrated limited tibial translation inappropriately transfers forces to the hips and low back. (16) Therefore as a general rule, assess whether the tibia and the spine are in parallel alignment (Figure 9).
A stance with feet forward, or with a slight degree of external rotation, and approximately shoulder width apart is desired as a wider stance will change the torque about the knee and hips as well as the muscle activity of the lower extremities. (2) As one descends the foot pressure should shift from the mid foot toward the heel and lateral foot during this loading phase. (5) Toes should remain on the ground to maintain balance (Figure 10). From the lateral view assess if the heel is rising, which may be due to an ankle dorsiflexion limitation of the joint or from overactive gastrocnemius muscles. (18) When assessing from the anterior and posterior view, knee valgus as noted above may be the result of an over pronation problem.
START POSITION KEY POINTS:
- Arms extended above head
- Feet shoulder width apart
- Feet pointing straight
- Eye gaze is fixed straight ahead
BOTTOM POSITION KEY POINTS:
- Arms stay straight
- No excessive forward lean
- Feet stay pointing straight
- Heels stay on the ground
- Knees stay in line with feet
It is of utmost importance that clients are pain free when performing any movement assessment. Refer to the NASM Essentials of Corrective Exercise Training book for recommendations. Part 2 of this article will discuss appropriate corrective exercise intervention strategies based on the movement dysfunctions identified here.
1) Escamilla, RF, Fleisig, GS, Zheng, N, Lander, JE, Barrentine, SW, Andrews, JR, Bergemann, BW, and Moorman, CT. Effects of technique variations on knee biomechanics during the squat and leg press. Med Sci Sports Exerc 33: 1552–1566, 2001a.
2) Schoenfeld, B. 2010. Squatting Kinematics and Kinetics and Their Application to Exercise Performance. Journal of Strength and Conditioning Research 24(12):3497-3506.
3) Chaudhari, A., et al. 2006. The mechanical consequences of dynamic frontal plane limb alignment for non-contact ACL injury. Journal of Biomechanics. Volume 39, Issue 2, 2006, Pages 330–338.
4) Myer, G., et al. 2008. Trunk and Hip Control Neuromuscular Training for the Prevention of Knee Joint Injury. Clin Sports Med 27:425-488.
5) Myer, G., et al. 2014. The back squat: A proposed assessment of functional deficits and technical factors that limit performance. Strength Cond J. 2014 December 1; 36(6): 4–27.
6) Clark, M., Lucett, S., Sutton, B. (2014) NASM Essentials of Corrective Exercise Training. Burlington, MA, USA: Jones & Bartlett Learning.
7) Ruivo, R., et al. 2014. Cervical and shoulder postural assessment of adolescents between 15 and 17 years old and association with upper quadrant pain. Braz J Phys Ther. 2014 July-Aug; 18(4):364-371.
8) Harman, K., et al. 2005. Effectiveness of an Exercise Program to Improve Forward Head Posture in Normal Adults: A Randomized, Controlled 10-Week Trial. The Journal of Manual & Manipulative Therapy Vol. 13 No. 3, 163- 176.
9) Quek, J., et al. 2012. Effects of thoracic kyphosis and forward head posture on cervical range of motion in older adults. Manual Therapy 1-7.
10) Harrison, D., et al. 1998. Elliptical Modeling of the Sagittal Lumbar Lordosis and Segmental Rotation Angles as a Method to Discriminate Between Normal and Low Back Pain Subjects. Journal of Spinal Disorders. Vol. 11(5).
11) Panjabi, M., White, A. (1990) Clinical Biomechanics of the Spine, Second Edition, USA: LWW.
12) Callaghan, J., McGill, S. 2000. Intervertebral disc herniation: studies on a porcine model exposed to highly repetitive flexion/extension motion with compressive force. Clinical Biomechanics 16:28-37.
13) Kavcic, N., et al. 2004. Determining the Stabilizing Role of Individual Torso Muscles During Rehabilitation Exercises. Spine Volume 29, Number 11:1254–1265.
14) Myer, G., et al. 2004. Rationale and Clinical Techniques for Anterior Cruciate Ligament Injury Prevention Among Female Athletes. Journal of Athletic Training. 39(4):352–364.
15) Hewett, T., et al. 2010. Understanding and Preventing ACL Injuries: Current Biomechanical and Epidemiologic Considerations – Update 2010. North American Journal of Sports Physical Therapy. Vol. 5(4):234-251.
16) Fry, A., et al. 2003. Effect of Knee Position on Hip and Knee Torques During the Barbell Squat. Journal of Strength and Conditioning Research, 2003, 17(4), 629–633.
17) Solomonow, B., et al. 1987. The synergistic action of the anterior cruciate ligament and thigh muscles in maintaining joint stability. Am J Sports Med 15: 207–213.
18) Riddle, D., et al. 2003. Risk Factors for Plantar Fasciitis: A Matched Case-Control Study. The Journal of Bone and Joint Surgery. 85-A(5):872-877.