1University of Zagreb, Faculty of Kinesiology, Zagreb, Croatia
Sex Differences in Regional Muscle Hypertrophy and Elbow Flexion and Extension Strength
Sport Mont 2025, 23(3), Ahead of Print | DOI: 10.26773/smj.251012
Abstract
Strength and hypertrophy are key factors in motor function. Although gender differences in muscle strength and size are well documented at the global level of muscle mass, less is known about how they manifest at the level of individual regions within the same muscle and whether differences in total muscle thickness are uniformly distributed along its entire length. Therefore, the goal of this research was to determine if there are differences in regional muscle thickness and elbow flexion and extension strength between male and female kinesiology students, and to examine the relationship between specific muscle regions and force production in these movements. The regional thickness of the biceps brachii and triceps brachii muscles was measured using B-mode ultrasound at three sites. The peak torque of elbow flexion and extension force was measured on an isokinetic dynamometer in a sample of 57 physically active university students, comprising 28 men and 29 women. It was shown that students have greater elbow flexion and extension strength and greater biceps and triceps brachii muscle thickness in all regions. Pearson's correlation showed a positive association between muscle thickness and the strength of elbow flexion and extension in both groups of subjects, but the patterns of association differed between male (r=0.33-0.65) and female (r=0.32-0.51) students. In men, elbow flexion strength was most closely associated with the distal part of the biceps brachii, whereas in women, stronger correlations were found in the proximal regions. Additionally, significant regional differences in hypertrophy were observed in the triceps brachii, which were more pronounced in women. In conclusion, distinct regions of a muscle may contribute differently to force production during elbow flexion and extension. Although minor sex-related differences in regional force contributions have been observed, the underlying physiological mechanisms remain unclear and require further investigation.
Keywords
muscle size, muscle hypertrophy, isokinetic strength, gender differences
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