Relationships between physical characteristics and biomechanics of lower extremity during the squat

Abstract

Background/objective There is a lack of information about relationship between physical characteristics and biomechanics of the lower extremity during the squat. Additionally, studies did not examine sex-related differences. The purpose of this study was to investigate relationships between physical characteristics and biomechanics of the lower extremity during the squat, and to determine if any sex differences are present. Methods Fifty three participants recruited (21.82 ± 2.3 years; 75.56 ± 14.98 kg; 171.57 ± 8.38 cm) performed three squats with 75% of one repetition maximum. Femur to tibia length ratio, hip and ankle joints’ flexibilities, and relative muscular strength were measured and used as physical characteristics. Net joint torques (NJT) and flexion angles of the lower extremity were extracted as dependent variables. Multiple regression (stepwise) analysis was conducted to examine the relationships with physical characteristics being factors. Pearson correlation coefficients were calculated to determine intercorrelations among the dependent variables. Results Relative muscular strength was related to hip NJT and knee flexion angle, and hip flexibility was related to ankle dorsiflexion. Hip and knee NJT showed moderate correlations with the corresponding flexion angles (r = 0.48-0.53; p < .01). Ankle dorsiflexion angle showed weak to moderate correlations with hip NJT and hip flexion angle (r = −0.36-0.50; p < .01) and a moderate correlation with knee NJT. No significant sex difference was observed (r = 0.52; p < .05). Conclusion Biomechanics of the lower extremity has been shown to correlate more with relative muscular strength and joint flexibility than with leg length ratio.

Biomechanics research on laterality effect between dominant and non-dominant during double roundhouse kick in the competitive taekwondo

“…Strengthening the ankle muscles is an effective approach to developing a dynamic balance of the limb in taekwondo athletes [ 51 ] and joint moments essentially depend on the magnitude of force generated by the contraction of the muscles or muscle groups associated with the joint [ 52 ]. Further, the maximum joint moment indicates the maximum value of moment output generated by the muscle groups during the corresponding movement of the joint, while the produced moment is related to the speed of movement of the segments at both ends of the joint [ 53 ], and as the speed of movement grows, the generated moment reduces [ 41 , 54 ].…”