Evaluating movement performance: What you see isn't necessarily what you get

Area of Science:

• Biomechanics
• Movement Analysis
• Sports Science

Background:

• Movement screening tools often assess symmetry to predict injury and enhance performance.
• Current tools primarily evaluate kinematic asymmetry, potentially underestimating underlying movement faults.
• Joint forces and muscle activity also contribute to movement asymmetry and injury risk.

Purpose of the Study:

• To investigate movement symmetry across kinematic, kinetic, and muscle activity components during a parallel squat.
• To compare the degree of symmetry between these different movement components.

Main Methods:

• Thirty-four healthy individuals performed five body-weight parallel squats.
• Motion capture, force plates, and electromyography (EMG) sensors recorded movement data.
• Symmetry was analyzed using cross-correlations and normalized root-mean-square (nRMS) values for joint angles, moments, and EMG.

Main Results:

• Kinematic components exhibited the highest symmetry at all analyzed joints (ankles, knees, hips).
• Kinetic and muscle activity components demonstrated poorer symmetry compared to kinematics.
• Muscle activity (EMG) was the least symmetric component during the parallel squat.

Conclusions:

• Movement symmetry varies significantly across kinematic, kinetic, and muscle activity domains.
• Relying solely on kinematics for movement evaluation may overlook critical asymmetries and potential injury risks.
• Comprehensive movement assessments should incorporate kinetic and muscle activity analysis for accurate fault identification.