INFLUENCE OF KNEE FLEXION DURING SQUAT WITH AND WITHOUT LOAD USING AN INTEGRATED KNEE-FLEXION ANALYSIS SYSTEM

Abstract

Purpose: The study analyzed the muscle activity during knee flexion while performing a squat with and without a load based on soft tissue deformation parameters (STDP) at four different angular positions of the vastus lateralis (VL) and vastus medialis (VM) muscles. Methods: An integrated knee-flexion analysis system is a novel tool used to analyze muscle activity during knee flexion and comprises hardware and software modules. A motion capture system and video cameras are interfaced with wireless electromyography (EMG) sensors, and the system software records the motion of the subjects during the squat and extracts relevant features. The STDP from the video of each knee flexion angle and data fusion of EMG, contain the root mean square value, mean absolute value, and integrated EMG of the EMG signals. Twelve healthy soldiers were used as test subjects using uniform criteria in a controlled environment. Results: A strong positive correlation was shown between features extracted using EMG and the STDP for the VL and VM muscles of all subjects. The Wilcoxon test (nonparametric) and paired-samples t-test results were significantly greater in the loaded than unloaded trials during activity of VL and VM muscles at greater knee flexion angles ([Formula: see text]). Conclusion: The outcomes of this study signify the prominence of knee flexion and the associated contiguous balance and co-activation of the VL and VM at 10[Formula: see text], 20[Formula: see text], 30[Formula: see text], and 40[Formula: see text] of knee flexion during squatting with and without an external load. Thus, greater knee flexion during the squat is an important factor for greater muscle activation.