Comparisons of muscle strength, size, and voluntary activation in pre- and post-pubescent males and females

Purpose The purpose of this study was to compare measurements of muscle strength, size, and activation of the forearm flexors in pre- and post-pubescent males and females. Methods Forty pre-pubescent (mean +/- 95% confidence interval, age = 9.79 +/- 0.35 years, n = 10 males, n = 10 females) and post-pubescent (age = 17.23 +/- 0.58 years, n = 10 males, n = 10 females) youth participated. Subjects completed maximal voluntary isometric contractions (MVICs) of the forearm flexors, and submaximal isometric step muscle actions at 30, 50, and 70% of the peak MVIC. Percent voluntary activation (VA) was quantified during all isometric muscle actions. Forearm flexor (biceps brachii and brachialis) muscle cross-sectional area (CSA) was quantified from ultrasound images. Results MVIC strength was expressed in absolute terms and normalized to CSA. Post-pubertal males were 130% stronger, had 101% greater CSA, and 17% greater maximal VA than pre-pubertal males, while post-pubertal females were 72% stronger, had 54% greater CSA, and 23% greater maximal VA than pre-pubertal females. When MVIC strength was normalized to CSA, the post-pubertal males were still 15% stronger than the pre-pubertal males, while the post-pubertal females were only 12% stronger than the pre-pubertal females. The responses for VA across intensity reflected differences in muscle activation strategies between pre- and post-pubertal males and females. Conclusion These results suggest that muscle size may account for a greater proportion of the growth and development-related differences in strength among males, while females may be more affected by changes in muscle activation. Regardless of sex, changes in muscle size and neuromuscular function influence strength increases during growth and development.

Automated summary

This study compared measurements of muscle strength, size, and activation of forearm flexors in pre- and post-pubescent males and females. Post-pubertal males showed significant increases in strength, CSA, and maximal VA compared to pre-pubertal males, while post-pubertal females also demonstrated improvements in these aspects. The findings suggest that muscle size plays a larger role in strength differences among males during growth and development, while changes in muscle activation may have a greater impact on females.