Menopause, Female Sex Hormones, Skeletal Muscle Mass and Muscle Protein Turnover in Humans.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing observational and mechanistic literature
PubMed 41707658 · doi:10.1002/jcsm.70232
What was done
This narrative review evaluated human evidence examining the impact of menopause and female sex hormone fluctuations on skeletal muscle mass and muscle protein turnover. The authors synthesized findings from cross-sectional and longitudinal cohort studies tracking body composition, as well as experimental trials evaluating basal muscle protein synthesis, anabolic responsiveness to resistance exercise and protein intake, and muscle protein breakdown.
What was found
Longitudinal (4 of 5) and cross-sectional (7 of 11) studies reported reductions in lean or muscle mass across the menopausal transition, with average decreases of -2.5% in perimenopausal and -5.7% in postmenopausal women compared to premenopausal controls. Most studies (10 of 11) measured lean body mass via DXA. Basal muscle protein synthesis was higher in older versus younger women (3 of 7 studies) or age-matched men (4 of 5 studies). However, muscle protein synthesis responses were blunted following resistance exercise (3 of 4 studies) and protein ingestion (3 of 6 studies) in older women. Direct human evidence assessing muscle protein breakdown across menopause is absent.
Why it matters
This review clarifies the physiological basis of accelerated muscle loss during the menopausal transition, identifying anabolic resistance to exercise and nutrition as potential targets for sarcopenia prevention.
Limits
The paper is a narrative rather than a systematic review. Most synthesized studies evaluated body composition using DXA rather than direct volumetric muscle imaging, which may underestimate true muscle loss. Data on postmenopausal muscle protein breakdown in humans are completely lacking, and findings regarding protein synthesis responses show inconsistency across small subsets of literature.