Abstract
Literature suggests that women display quadriceps dominance during some closed chain exercises which may contribute to higher risk of anterior cruciate ligament tears as compared to males. However, whether sex-based differences in quadriceps activation are present during open chain knee extension at increasing loads remains unclear. PURPOSE: This study aimed to test if vastus medialis obliquus (VMO) and vastus lateralis (VL) surface electromyography (EMG) amplitudes differ between recreationally trained male and female university students during dynamic knee extensions at 30%, 60%, and 90% of their predicted 1-repetition maximum (1RM). METHODS: 16 males (21.1 ± 1.9 y, 82.9 ± 21.0 kg, 177.1 ± 8.3 cm) and 10 females (21.5 ± 1.4 y, 60.6 ± 12.9 kg, 161.4 ± 5.1 cm) completed two testing sessions separated by one week. Participants were strength tested for their predicted leg extension 1RM. During the second session, EMG electrodes were placed on the VMO and VL. Participants performed 5-s maximal voluntary isometric contractions (MVICs) to establish normalization values. Participants then completed four dynamic repetitions at 30%, 60%, and 90% of their predicted 1RM. EMG signals were recorded during each set, and average VMO and VL amplitudes from repetitions 2-4 were expressed as a percentage of MVIC. Sex differences across the three load specific outcomes were evaluated separately for VMO and VL using one-way MANOVAs with an alpha level set to p < 0.05. RESULTS: There were no significant sex-based differences in normalized VMO muscle activation at 30% 1RM (males: 83.1± 4.5%, females: 77.4 ± 5.7%; p = 0.438), 60% 1RM (males: 113.8 ± 5.1%, females: 104.4 ± 6.4%; p = 0.263), or 90% 1RM (males: 141.7 ± 7.9%, females: 134.0 ± 10.0%; p = 0.550). Similarly, no significant sex-based differences were detected for normalized VL muscle activation at 30% 1RM (males: 87.7 ± 5.2%, females: 79.7 ± 6.5%; p = 0.346), 60% 1RM (males: 115.0 ± 5.7%, females: 106.5 ± 7.2%; p = 0.358), or 90% 1RM (males: 140.6 ± 8.3%, females: 130.7 ± 10.4%; p = 0.468). CONCLUSION: This sample displayed no significant sex-based differences in normalized VMO and VL EMG amplitude during single-joint knee extensions at low, intermediate, and heavy loads. This data supports that when lifting relative loads, males and females display similar trends in quadricep muscle activation.
Recommended Citation
Calovini, Admar L.; Johannessen, Thomas L.; Ghigiarelli, Jamie J.; and Gonzalez, Adam M.
(2026)
"Sex-based Comparison of Quadricep Activation Across Dynamic Knee Extension Loads,"
International Journal of Exercise Science: Conference Proceedings: Vol. 15:
Iss.
9, Article 6.
Available at:
https://digitalcommons.wku.edu/ijesab/vol15/iss9/6