The Performance Matrix
MOVEMENT EFFICIENCY FOR A LIFETIME

Observation of single leg squat - kinematics and EMG

13th January 2014

This paper looked at healthy active women. They made an observation of movement rather than a movement control test - would the results, between groups, be different in people with pain and if they had looked at the control of movement?

In Press Clinical Biomechanics

Authors Hollman J , Galardi C, Lin I-H, Voth B, Whitmarsh C

Abstract


Background
Hip muscle dysfunction may be associated with knee valgus that contributes to problems like patellofemoral pain syndrome. The purpose of this study was to (1) compare knee and hip kinematics and hip muscle strength and recruitment between “good” and “poor” performers on a single-leg squat test developed to assess hip muscle dysfunction and (2) examine relationships between hip muscle strength, recruitment and frontal plane knee kinematics to see which variables correlated with knee valgus during the test.


Methods
Forty-one active women classified via visual rating as “good” (n = 21) or “poor” (n = 20) performers on the test participated. Participants completed 5-repetition single-leg squat tests. Isometric hip extension and abduction strength, gluteus maximus and gluteus medius recruitment, and 3-dimensional hip and knee kinematics during the test were compared between groups and examined for their association with frontal plane knee motion.

Findings
“Poor” performers completed the test with more hip adduction (mean difference = 7.6°, 95% CI = 0.8° to 14.4°) and flexion (mean difference = 6.3°, 95% CI = 3.2° to 9.4°) than “good” performers. No differences in knee kinematics, hip strength or hip muscle recruitment occurred. However, secondary findings indicated that increased medial hip rotation (partial r = 0.94) and adduction (partial r = 0.42) and decreased gluteus maximus recruitment (partial r = 0.35) correlated with increased knee valgus.

Interpretation
Whereas hip muscle function and knee kinematics did not differ between groups as we’d hypothesized, frontal plane knee motion correlated with transverse and frontal plane hip motions and with gluteus maximus recruitment. Gluteus maximus recruitment may modulate frontal plane knee kinematics during single-leg squats.

 

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