Sexual dimorphism in human muscle ageing

Primary sarcopenia is a progressive, age-related decline of skeletal muscle strength, size, and quality, the socio-economic and health impacts of which are set to increase due to global ageing. Despite differences in the physiology of female and male skeletal muscle being well characterised, their alteration with age is less clear. Here we report a striking sexual dimorphism in arm muscle ageing in 478,438 UK Biobank participants aged 40-82 yr. Although the sex difference in age-related arm muscle strength decline is modest, muscle mass loss is considerably more pronounced in males, both in absolute and percentage terms. We also present two alternative measures of muscle quality, each of which exhibits substantially greater age-related decline in females. These trends hold across independent analyses of separate cross-sectional and longitudinal participant groups, persist after accounting for systematic size differences between the sexes, and are apparent irrespective of female menopause status and hormone replacement therapy usage history, despite an sharp reduction in female strength during the perimenopause. Our findings confirm the importance of sex to effective diagnosis and mitigation of sarcopenia, and prompt consideration of the physiological basis of this pronounced sex difference in skeletal muscle ageing.