Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
©Journal of Sports Science and Medicine (2019) 18, 101 - 108

Research article
Comparison of Quadriceps and Hamstring Muscle Activity during an Isometric Squat between Strength-Matched Men and Women
Sophia Nimphius1, Jeffrey M. McBride2, , Paige E. Rice1,2, Courtney L. Goodman-Capps2, Christopher R. Capps2
Author Information
1 Centre for Exercise and Sports Science Research, School of Medical and Health Sciences, Edith Cowan University, Joondalup, Australia
2 Neuromuscular and Biomechanics Laboratory, Department of Health and Exercise Science, Appalachian State University, Boone, North Carolina, USA

Jeffrey M. McBride
✉ Neuromuscular & Biomechanics Laboratory, Department of Health and Exercise Science, Appalachian State University 045 Convocation Center, Boone, NC 28607, USA
Publish Date
Received: 16-10-2018
Accepted: 17-12-2018
Published (online): 11-02-2019
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The primary purpose of this investigation was to determine whether strength-matched men and women exhibit a different magnitude and ratio of leg muscle activity during a maximal voluntary isometric squat. The secondary purpose was to assess the effect of normalization method on differences in strength between men and women. Thirty-two men (n = 16) and women (n = 16) were successfully strength-matched (≤10% difference) by maximal force produced during an isometric squat (IS) when normalized to body weight. Subjects first performed a maximal isometric knee extension (IKE) and knee flexion (IKF) followed by the IS and muscle activity (EMGmax) was recorded for the vastus medialis (VMO), vastus lateralis (VL), semitendinosus (ST) and biceps femoris (BF). Muscle activity during the IS was expressed relative to the maximums observed during the IKE and IKF (%EMGmax). The results indicate that VMO, VL, ST and BF %EMGmax were not significantly different (p > 0.05) between men and women during the IS (Men VMO = 136.7 ± 24.9%, Women VMO = 157.1 ± 59.8%, Men VL = 126.2 ± 38.2%, Women VL = 128.1 ± 35.5%, Men ST = 25.5 ± 13.6%, Women ST = 25.2 ± 21.8%, Men BF = 46.1 ± 26.0%, Women BF = 42.2 ± 24.8%). Furthermore, the VMO:VL and hamstring to quadriceps (H:Q) %EMGmax ratio were not significantly different between groups in the IS (Men VMO:VL = 1.15 ± 0.28, Women VMO:VL = 1.22 ± 0.26, Men H:Q = 0.28 ± 0.14, Women H:Q = 0.24 ± 0.20). This investigation indicates that the magnitude of muscle activity and the ratios examined are not significantly different between men and women in a maximal voluntary isometric squat when matched for normalized strength. Future investigations should consider subject strength and normalization procedures in the experimental design to elucidate possible sex differences in neuromuscular performance capabilities.

Key words: Knee extension, knee flexion, agonist, antagonist

           Key Points
  • Agonist/Antagonist and medial/lateral muscle activity is not different between men and women when they are strength matched.
  • Strength should be considered as a confounding variable when examining potential sex or gender differences in neuromuscular function.
  • Strength normalization method can influence results and should be chosen on relevance to task.
  • This investigation provides a foundation based on an isometric task to now examine dynamic tasks to see if similar results exist.
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