knee Archives - PostureScreen, LeanScreen, RemoteScreen, SquatScreen, PostureRay

SQUAT FORM – WHAT DOES IT TELL US? PART 1

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.

Figure 1

Figure 2

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)

HEAD POSITION

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)

Figure 3

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)

Figure 4

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)

Figure 5

PELVIC POSITION

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)

Figure 6

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.

Figure 7

TIBIAL TRANSLATION

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).

Figure 8

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Figure 9

FOOT POSITION

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.

Figure 10

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.

REFERENCES

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.

HOW TO PREVENT ACL INJURIES AND KEEP YOUR CLIENTS ON THE COURT THROUGH CORRECTIVE EXERCISE PROGRAMMING

Knee ACL iStock_000012214665_XXXLarge resized

(Republished with permission www.WebExercises.com)

Anterior cruciate ligament (ACL) injuries are one of the most common among young female athletes occurring at a conservative estimate of 38,000 incidences per year. (1) With the cost of a surgical repair ranging between $17,000-$25,000 (2), the economic impact is significant, not to mention the long term sequela to the athlete which includes a significantly greater risk of osteoarthritis in the future. (3) Approximately 80% of these injuries are non-contact, suggesting many of them can be prevented. (4)

The ACL is a ligament running from the posterior femur anteriorly to the tibia. It originates from deep within the notch of the distal femur and its proximal fibers fan out along the medial wall of the lateral femoral condyle. The ACL attaches in front of the intercondyloid eminence of the tibia and is blended with the anterior horn of the medial meniscus. It provides approximately 85% of the restraining forces preventing anterior tibial translation. It also limits excessive internal or external rotation of the tibia. (5)

Knee Normal ACL

Pubertal females are four to six time more likely to sustain an ACL injury compared to males, thereby representing the largest demographic of athletes at potential risk. (6) This is due to a variety of reasons including the rapid growth of the femur and tibia that generate larger joint forces making neuromuscular control of the lower extremities and trunk much harder. A lack of core stability has also been shown to influence knee injuries in female athletes as reported by Zazulak and colleagues. They demonstrated this decrease in core neuromuscular control increases uncontrolled trunk displacement leading to higher knee ligament strain and ACL injury. (7)

Knee ACL Tear

In order to identify at risk athletes, implementing a screening method such as the Landing Error Scoring System (LESS) test or Tuck Jump test is essential when working with all athletes in this age range. The LESS involves having the athlete stand on a 12-inch box and then jumping forward with both feet to a predetermined line followed by an immediate jump for maximal height.

The Tuck Jump test requires the athlete to perform repeated jumps flexing the knees toward the trunk for a duration of 10 seconds. Both tests have been validated in the literature to identify neuromuscular imbalances. (9) (10) (For more information on each test please refer to NASM Essentials of Corrective Exercise Training for a detailed review. (8))

One of the most common muscular imbalances identified in females over males is increased knee valgus and coronal plane rotation that has been shown to be a predictor of injury. This common finding has been associated with increased quadriceps firing and decreased gluteal activation in females, causing anterior shear stress on the tibia, which is then transferred to the ACL. (11)

Knees cave in

In order to establish proper gluteus maximus activation, a hip bridge with a resistance band above the knees is recommended. Choi and colleagues found that gluteus maximus EMG activity was significantly greater while anterior pelvic tilt angle was significantly lower in the hip bridge with isometric hip abduction compared to the hip bridge without the band. Therefore, they concluded that performing hip bridges with isometric hip abduction against isometric elastic resistance can be used to increase gluteus maximus EMG activity and reduce anterior pelvic tilt during the exercise. (16)

Exercise 1a

Hip Bridge with Resistance Band – Begin by lying on the floor with knees bent and feet flat on the floor. Place a resistance band around the thighs just above the knees. Slightly abduct the legs while simultaneously performing a hip bridge. Slowly lower to start position without bringing knees together. Perform 3 sets of 10 repetitions.

Valgus collapse of the knee can also be associated with weakness of the hip external rotators and gluteus maximus. Paterno and colleagues identified this finding as an eight times greater risk of sustaining a second ACL injury. (12) Performing the clam shell exercise will mitigate hip rotator weakness, helping to minimize this potential risk.

Exercise 2a Exercise 2b

Clam Shell with Resistance Band – Begin by lying on the side with knees together and bent to 90 degrees with resistance band around knees. Lift top knee upward while keeping feet touching. Continue lifting knee to the point just before pelvis begins to move. Perform 3 sets of 10 repetitions.

The hamstrings are also synergistic to the knee helping to stabilize the tibia against the anterior forces created by the quadriceps. A stability ball leg curl is a great open kinetic chain exercise and has been showed to elicit high EMG activity of the hamstring muscles while co-contracting the core musculature. (13)

Exercise 3a Exercise 3b

Stability Ball Leg Curl – Begin lying face up with arms extended at sides and ankles on top of the stability ball. Activate core and form a bridge position. Then flex knees, bending legs as you draw the ball inward. Reverse the movement, extending knees, and return to start position. Perform 3 sets of 10 repetitions.

In order to establish lateral stability, the side step “monster walk” with knees bent is a functional and effective exercise. Increased hip abduction strength has been shown to improve the ability of female athletes to control lower extremity alignment. (14) When performing this exercise, the stepping motion should be performed in a squat position rather than an upright straight leg position in order to generate greater gluteus maximus and medius muscle activity. (15)

Exercise 4a Exercise 4b

1/4 Squat with Lateral Steps Using Resistance Band – Begin standing with a resistance band around the thighs just above the knees. Keep your feet and knees apart enough to put resistance on the band. Perform a ¼ squat with both feet supporting body weight. Hold squat position, shift weight fully onto one leg. Take a lateral step with the other un-weighted leg. Repeat, taking several lateral steps in one direction and then doing the same in the other direction.

Another potential risk of injury occurs when landing with a knee flexion angle of less than 45 degrees. Therefore, performing long jumps can be used to train proper landing patterns. This exercise is similar to the Tuck Jump test with the addition of forward motion and is also a great way to introduce plyometric exercises. If the athlete is unable to “stick” the landing with toes straight ahead and no inward knee motion, then regress them to submaximal jumps of a shorter distance until perfect technique can be attainted. (6)

Exercise 5a Exercise 5b

Long Jump to Backward Hop – Begin in quarter squat position. Jump forward in an explosive long jump trying to “stick” the landing for 3-5 seconds. Make sure the knees are flexed to approximately 90 degrees on landing. Hop backwards two or three times returning to the start position. Perform 3 sets of 10 repetitions.

One of the most significant findings, which has been shown to reduce the incidence of ACL injuries in a number of studies, is the incorporation of high-intensity plyometric exercises as part of the training program. The split jump offers these plyometric benefits.

Exercise 6a Exercise 6b

Split Jumps – Begin in a split stance lunge position with arms raised at shoulder level. Jump upward and quickly reposition legs and land with feet in opposite positions. Raise arms while you are jumping. Continue jumps by alternating leg positions. Perform 3 sets of 10 repetitions.

If an athlete fatigues to the point that she can no longer perform the exercise perfectly, then she should be instructed to stop. The duration of each completed exercise should be noted with the goal of the next training session to continue to improve technique and to increase volume or intensity.

In addition to the NASM corrective exercise continuum of inhibit, lengthen, activate and integrate, three additional components should also be considered as part of a comprehensive training protocol. These are biomechanically correct movement patterns as noted above; neuromuscular patterning based on the identification of underlying neuromuscular imbalances as found in the assessment test; and constant biomechanical assessment through the LESS, Tuck Jump or similar test with feedback and verbal cueing to athlete both during and after training. (10)

An incorporation of a core stabilization program is not only integral but also essential in order to provide dynamic stability for the lower extremities. A weak core results in energy leakage as described by McGill requiring the weaker joints to make up for this difference. An example of this is when jumping or changing running direction, the lower extremity musculature must compensate for the lack of core stability, negatively effecting performance. (17)

All of the above displayed exercises are easy to execute and include minimal risks if performed as described. To achieve satisfying results, it is important do them on a regular basis and for a minimum of 4 weeks. The general guideline for progressing student athletes is the “10% rule”, where total training (intensity, frequency, duration, or any combination) is not increased more than 10% per week. Although there are many approaches to knee strengthening, hopefully this has provided insight into some basic strengthening strategies. Should your client’s condition worsen at any time, an evaluation with a medical professional would be warranted.

To download a copy of the above exercises, click here.

References

1) Toth AP, Cordasco FA. Anterior cruciate ligament injuries in the female athlete. J Gend Specif Med. 2001; 4:25–34.

2) de Loes, M, et al. A 7-year study on risks and costs of knee injuries in male and female youth participants in 12 sports. Scand J Med Sci Sports. 2000;10(2):90-97.

3) Ruiz AL, Kelly M, Nutton RW. Arthroscopic ACL reconstruction: a 5-9 year follow up. Knee. 2002;9(3):197-200.

4) Sadoghi, P, et al. 2012. Effectiveness of Anterior Cruciate Ligament Injury Prevention Training Programs. J Bone Joint Surg Am. 2012; 94:1-8.

5) Lowe, R. Anterior Cruciate Ligament (ACL). Retrieved from: http://www.physio-pedia.com/Anterior_Cruciate_Ligament_(ACL)

6) Myer, G. 2004. Rationale and Clinical Techniques for Anterior Cruciate Ligament Injury Prevention Among Female Athletes. Journal of Athletic Training 2004;39(4):352–364.

7) Zazulak BT, Hewett TE, Reeves NP, et al. The effects of core proprioception on knee injury: a prospective biomechanical–epidemiological study. Am J Sports Med 2007;35(3):368–73.

8) Clark, MA, Lucett, SC. (2014). NASM Essentials of Corrective Exercise Training. Burlington, MA. Jones & Bartlett Learning.

9) Padua, D. et al. 2011. Journal of Sport Rehabilitation. 20, 145-156.

10) Myer, et al. 2008. Tuck Jump Assessment for Reducing Anterior Cruciate Ligament Injury Risk. Athl Ther Today. 2008 September 1; 13(5): 39–44.

11) Zazulak, B, et al. Gender Comparison of Hip Muscle Activity During Single-Leg Landing. Journal of Orthopaedic & Sports Physical Therapy.

12) Paterno, M, et al. Biomechanical Measures During Landing and Postural Stability Predict Second Anterior Cruciate Ligament Injury After Anterior Cruciate Ligament Reconstruction and Return to Sport. Am J Sports Med October 2010 vol. 38 no. 10 1968-1978.

13) Panagiotis, T., et al. 2015.  Muscle and intensity based hamstring exercise classification in elite female track and field athletes: implications for exercise selection during rehabilitation. Open Access Journal of Sports Medicine. 6:209-217.

14) Myer , G, et al. 2008. Trunk and Hip Control Neuromuscular Training for the Prevention of Knee Joint Injury. Clin Sports Med 27:425–448.

15) Berry, et al. 2015. Resisted side-stepping: the effect of posture on hip abductor muscle activation. Journal of Orthopaedic & Sports Physical Therapy.

(16) Choi, C, et al. 2014. Isometric hip abduction using a Thera-band alters gluteus maximus muscle activity and the anterior pelvic tilt angle during bridging exercise. Journal of Electromyography and Kinesiology.

(17) McGill, S. Core Training: Evidence Translating to Better Performance and Injury Prevention. Strength and Conditioning Journal. Vol 32(3):33-46.

(18) Myer, G. 2006. The effects of plyometric vs dynamic stabilization and balance training on power, balance, and landing force in female athletes. Journal of Strength and Conditioning Research. 20(2), 345-353.

THE AUTHOR

DAVID CRUZ, DC, CSCS, FMS, SFMA

Dr. David Cruz practiced as a sports chiropractor for 18 years treating athletic injuries, from weekend warriors to professional athletes. He received his bachelor’s of science degree in athletic training and has completed graduate course work in kinesiology. He is a Certified Strength and Conditioning Specialist (CSCS) as well as having both FMS and SFMA certifications. The combination of his background in sports medicine and interest in technology made him passionate about bringing these two worlds closer together, resulting in the foundation of his company WebExercises in 2005.
WebExercises is an end-to-end solution for exercise rehabilitation professionals and is currently integrated with several EHR companies. In addition to WebExercises.com, Dr. Cruz is co-founder and partner of two other software businesses within the health care and technology industry.