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Biomechanics of the Single Leg Squat

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on 6 April 2014

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Transcript of Biomechanics of the Single Leg Squat

Biomechanics of the Single Leg Squat
Muscles of the Hip & Pelvis In Squatting
Estimated over 200 muscles involved!
Knee flexion-
Hamstrings
Knee extension-
Quadriceps
Glut Max
Knee IR-
Piriformis Glut max
Postural Support-
Abdominals, Erector Spinae, Trapezius, Rhombiods
The Hip
Ball-and-socket joint
Composed of sacrum, ilium, pubis
Disperses forces placed upon it from body weight and ground reaction forces
Compression, shearing, and tensile forces
Width differs based on gender
Arthro-/Osteokinematics
Sacrum on Ilia:
Flex- base moves ant, apex post.
Ext- base moves post, apex ant
LE on Sacrum:
Hip Flex- ilium post rotate
Hip Ext- ilium ant rotate
Hip Jt:
Flex- post spin, ant roll/post glide. Ext opp
IR- ant roll, post glide. ER opp
Boys vs. Girls: Battle of the Squats
Anteversion vs. Retroversion
Normal anteversion = 8-15 degrees
Excessive anteversion = toe-in, pronation, medial tibial/femoral torsion, lack of hip ER
Excessive retroversion = toe-out, supination, lateral tibial/femoral torsion
With compensated anteversion, pt may collapse medially
With compensated retroversion, pt may collapse laterally
Hip Abductor Muscle Weakness
Importance of full hip extension
Hip extensor weakness or hip flexor contracture disrupts normal biomechanics of standing

Metabolic expenditure increases as hip extensors fire to counter shift in force of body weight

Leads to less optimal alignment of articular cartilage and less protection of bone within the joint
Quiz Questions
1) True or False: Females often present with a greater hip adduction angle as they move through the single leg squat.

2) A greater hip adduction angle and following medial collapse can most likely be attributed to...
A) Tight adductors
B) Weak Glut Med
C) Weak Quads
D) Lumbar Scoliosis

3) What is the most active muscle during the single leg squat?
A) Glut Max
B) Glut Med
C) Quads
D) Popliteus
E) None of these are active

References
Edmondston S, Leo Y, Trant B, Vatna R, Kendell M, Smith A. Symmetry of trunk and femoro-pelvic movement respones to single leg loading tests in asymptomatic females. Manual Therapy. 2013 18: 231-236.

Graci V, Van Dillen LR, Salsich GB. Gender differences in trunk, pelvis and lower limb kinematics during a single leg squat. Gait and Posture, 2012; 36(3): 461-466

Neumann DA.
Kinesiology of the Musculoskeletal System
. 2nd ed. St. Louis, MO: Mosby Elsevier; 2010.

Schoenfield, B. Squatting kinematics and Kinetics and their application to exercise importance.
Journal of Strength and Conditioning Research
. 2010; 24 (12): 3497-506.
Clinical Relevance
Biomechanics of the hip relates to the incidence in PFP and ACL tears in females particularly!
Understanding the musculature and how imbalances affect all populations, including the aging population
Osteoarthritis
Grant Fall (the G Man)
Chelsea (proprioceptive probs) Garascia
(Tim Jim) Jordon Houtz
Laura (THE official) Kate Morse
Jen (Jenga) Lund
Associated with several medical conditions
Patients with a painful or unstable hip often experience “disuse” weakness and atrophy in the abductor muscles
Trendelenberg Sign
May not be able to perform certain activities
Artho/Osteo Cont'd
Tibio Femoral Jt
Flex- IR, post roll, ant glide. Ext opp
Patello Femoral Jt
Flex-glides inf. Ext opp

Video Analysis
Female SL Squat (Anterior View)
Female SL Squat (Lateral View)
Male SL Squat (Lateral View)
Male SL Squat (Anterior View)
Why a Single Leg Squat??
• Used to examine the kinematics of patients with lower extremity pain.
• Bilateral comparison
• Importance: to understand movement responses for better assessment and decision making

Males and Females use different movement strategies at each level of the kinetic chain.....
Transverse Plane & Frontal Plane
• Greater hip Adduction seen in females leads to a medial collapse.
o Edmondston et al. indicate the development of a passive strategy with single leg squat.
o Focus on the glute med!
o Glut med strength associated with femoro-pelvis adduction angle.

Fracture of the hip
Sagittal Plane Movements
• Less hip flexion in females during all athletic maneuvers.
• Trunk movement in the sagittal plane.
o Transmission of forces affect mechanisms of potential injury
o Less trunk flexion less hip and knee flexion during the drop phase of the squat.
o Females erect posture due to lack of hip extensor strength in forward movement of COM.
o Quadriceps recruitment.

Rotated toward WB limb
Lean toward NWB limb
Greatest hip adduction angle = 22.2 deg
Total frontal plane movement = 14.2 deg
Rotated toward WB limb
Lean toward WB limb
Greatest hip adduction angle = 12.7 deg
Total frontal plane movement = 9.5 deg
Very little trunk flexion
Greatest hip flexion angle = 68.2 deg
Significant trunk flexion
Greatest hip flexion angle = 104.4 deg
Bonus Question :)
Who had the best squat?
A) Tim
B) Chelsea
C) Meri
D) Grant
Full transcript