Effects of step lengths on biomechanical characteristics of lower extremity during split squat movement

Qingquan Song; Mujia Ma; Hui Liu; Xiaobin Wei; Xiaoping Chen

doi:10.3389/fbioe.2023.1277493

Effects of step lengths on biomechanical characteristics of lower extremity during split squat movement

Front Bioeng Biotechnol. 2023 Nov 10:11:1277493. doi: 10.3389/fbioe.2023.1277493. eCollection 2023.

Authors

Qingquan Song¹, Mujia Ma², Hui Liu³, Xiaobin Wei¹, Xiaoping Chen^{1

4}

Affiliations

¹ School of Strength and Conditioning Training, Beijing Sport University, Beijing, China.
² Biomechanics Laboratory, School of Sport Science, Beijing Sport University, Beijing, China.
³ China Institute of Sport and Health Science, Beijing Sport University, Beijing, China.
⁴ Centre for Sports Research, China Institute of Sport Science science, Beijing, China.

Abstract

Objective: To quantify the effects of increasing the step length of the split squat on changes in kinematics, kinetics, and muscle activation of the lower extremity. Methods: Twenty male college students participated in the test (age: 23.9 ± 3.7, height: 175.1 ± 4.9). Data on kinematics, kinetics, and EMG were collected during split squat exercise at four different step lengths in a non-systematic manner. One-way repeated measurements ANOVA were used to compare characteristic variables of peak angle, moment, and RMS among the four step length conditions. Results: The step length significantly changes the peak angles of the hip (p = 0.011), knee (p = 0.001), ankle (p < 0.001) joint, and the peak extension moment of the hip (p < 0.001), knee (p = 0.002) joint, but does not affect the ankle peak extension moment (p = 0.357) during a split squat. Moreover, a significant difference was observed in the EMG of gluteus maximus (p < 0.001), vastus medialis (p = 0.013), vastus lateralis (p = 0.020), biceps femoris (p = 0.003), Semitendinosus (p < 0.001), medialis gastrocnemius (p = 0.035) and lateralis gastrocnemius (p = 0.005) during four step lengths, but no difference in rectus femoris (p = 0.16). Conclusion: Increases in step length of split squat had a greater activation on the hip extensor muscles while having a limited impact on the knee extensor muscles. The ROM, joint moment, and muscle activation of the lead limb in the split squat all should be considered in cases of individual preventative or rehabilitative prescription of the exercise. Moreover, the optimal step length for strength training in healthy adults appears to be more suitable when it is equal to the length of the individual lower extremity.

Keywords: EMG; biomechanics; lower extremity; rehabilitation; split squat.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This study was supported by the China National Natural Science Foundation under Grant No. 12132009 and the Intelligent Military Staff Physical Training and Monitoring No. HX2022000451.