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Abstract

Mechanisms of accelerated declines in maximal strength with age in post-menopausal females are poorly understood. Declines in neuromuscular function may occur independently of lower body declines in maximal strength, yet this relationship remains poorly understood across menopausal status. PURPOSE: To assess lower body maximal strength and neuromuscular activation between pre- and post-menopausal women during a one-repetition maximum (1RM) leg press on muscles of the vastus lateralis (VL) and rectus femoris (RF). METHODS: This secondary analysis used a cross-sectional design including eleven untrained women (pre-menopausal, n=6; age=23.3±4.3 years; height=160.6±8.3 cm; weight=60.5±11.6 kg; post-menopausal, n=5; age=61.0±3.3 years; height=164.2±8.0 cm; weight=77.1±9.3 kg). 1RM strength was assessed using NSCA guidelines on a standard leg press machine. Surface electromyography (EMG) was collected from the VL and RF using standardized skin preparation and electrode placement. EMG signals were analyzed using EMGRMS to quantify maximal muscle activation during 1RM efforts. Independent samples t-tests were performed to examine differences between pre- and post-menopausal groups, with Hedges’ g reported as an effect size. RESULTS: Pre- and post-menopausal women demonstrated similar leg press 1RM strength (pre: 100.2 ± 17.1 kg; post: 94.3 ± 36.6 kg, p=0.756). Despite comparable strength, maximal neuromuscular activation during 1RM efforts was significantly lower in post-menopausal women for both the VL (pre: 0.242 ± 0.068; post: 0.120 ± 0.080; p=0.027) and RF (pre: 0.230 ± 0.087; post: 0.078 ± 0.037; p=0.006), with large effect sizes observed (Hedges’ g=1.52, 1.99 respectively). CONCLUSION: Post-menopausal women exhibit substantially reduced maximal neuromuscular activation via EMGRMS during high-intensity lower body efforts despite similar maximal strength compared to pre-menopausal women. These findings suggest an age- or hormone-related reduction in neural activation capacity that may precede declines in muscular strength.

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