Sex Hormones and Menopause Hormone Therapy Predict Muscle Strength Across the Lifespan

Aging is associated with declines in muscle strength, yet after menopause the relative rate of decline is greater in females than males. Whether sex hormones are predictive of strength across the lifespan and with aging is largely unknown. This study assessed the impact of sex hormone concentrations and menopause hormone therapy (MHT) on muscle strength in aging. Hand grip strength, sex hormone concentrations (total testosterone, bioavailable testosterone (FAI), estradiol, bioavailable estradiol (FEI)), and history of female MHT use were extracted or calculated from the National Health and Nutrition Examination Survey (NHANES) for 4,330 participants (2,194 females). Males were 36-40% stronger than females throughout adulthood. One-year averages of total testosterone (r=0.48, p<0.01), FAI (r=0.86, p<0.001), and FEI (r=0.71, p<0.001) were associated with strength in males. All hormones were correlated with strength in females, with estradiol (r=0.81, p<0.001) and FEI correlations (r=0.82, p<0.001) the strongest. Multiple linear regressions demonstrated that the FAI was a predictor of strength, while total testosterone was not, in both males and females and that estradiol and FEI were indicative of female strength in later adulthood. Hand grip strength in older females with a history of MHT use was 1.9kg greater than those with no MHT history (p<0.01) and this advantage widened with age (2.4% at 60 yrs to 14.3% at ≥80 yrs). This study strongly suggests (1) age-related declines in endogenous sex hormones, particularly bioavailable hormones, contribute to strength reductions with aging; and (2) MHT may have the potential to offset meaningful strength reductions with advanced aging.