Menopause, Female Sex Hormones, Skeletal Muscle Mass and Muscle Protein Turnover in Humans.

Sarcopenia describes the loss of muscle mass and function with age. The increase in prevalence of sarcopenia in women appears to coincide with the onset of menopause, which is characterized by large changes to the hormonal milieu such as decreased oestrogen and progesterone concentrations. Although the timing of menopause and sarcopenia may coincide, there is a lack of high-quality evidence demonstrating a link between the two. This narrative review aims to assess evidence for the effects of menopause on muscle mass and muscle protein turnover. Longitudinal (n = 4/5) and cross-sectional (n = 7/11) studies demonstrate a reduction in lean or muscle mass across the menopausal transition with -2.5% and -5.7% reductions in perimenopausal and postmenopausal women, respectively, compared to premenopausal women. Most of this evidence (n = 10/11) is taken through assessment of lean body mass via dual-energy x-ray absorptiometry (DXA), which may underestimate changes in muscle mass. Assessment on changes to muscle protein turnover is largely limited to short-term measures of muscle protein synthesis (MPS), which may be elevated in older women versus younger women (n = 3/7) or age-matched males (n = 4/5). MPS responses to anabolic stimuli, such as resistance exercise (n = 3/4) or protein ingestion (n = 3/6), may be blunted in older women. Evidence assessing muscle protein breakdown (MPB) is lacking; however, evidence from animal and cell models demonstrates the role of estradiol in suppressing MPB, which may contribute to an increase in MPB following menopause. Advancements in understanding the role of the menopausal transition in the regulation of muscle mass, and subsequent effectiveness of interventions such as exercise or exogenous hormone provision will enable healthy ageing and sarcopenia prevention in older women.