The Parallel Squat: A Comparison Between Kinematic, Kinetic, and Muscle Activity Components of Measurement

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McAllister, Megan
Biomechanics , Movement quality , Movement symmetry , Kinematics , Kinetics
Movement quality screening tools have been developed to reduce the risk of injury and enhance physical performance. These screening tools use observational techniques to analyze movement and identify faulty movement patterns. One variable that is used in some screening tools and that is a valid predictor of injury is movement asymmetry. The issue is that screening tools are currently assessing asymmetry from a kinematic perspective by observing the individual during their movement execution, while discounting potential asymmetric behaviour at the kinetic or muscle activity components of movement. The purpose of this study was to evaluate movement asymmetry from a kinematic, kinetic, and muscle activity component to identify whether differences exist between the components of movement. Kinematic, kinetic, and muscle activity data were collected from thirty-four healthy young adults as they performed twenty-five parallel squats in five conditions: normal, slow metronome, normal metronome, fast metronome, and weighted squat. The kinematic component was represented by joint angles, while the kinetic component was represented by joint moments and the muscle activity component was represented by electromyography amplitude. Cross-correlations and normalized RMS values were calculated between the left and right ankle, knee, and hip at each component of measurement. Multiple two-way repeated measures ANOVAs assessed the difference between the conditions and the components of measurement. Results demonstrated a significant difference in cross-correlations and normalized RMS values between the kinematic, kinetic, and muscle activity components at the ankle, knee, and hip. Generally, there was no significant difference between the conditions in terms of asymmetry measures. These results present an important consideration for movement quality screening tools: are we getting the full picture when evaluating movement using observational techniques and focusing on kinematic measures?
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