Sex Hormones and Changes in Muscle and Lean Mass, Physical Function and Activity in Men in the 9th-10th Decades of Life

CONTEXT: There is limited data of the associations between sex hormones and muscle mass and physical function in men over 80 years old. OBJECTIVE: This study evaluated associations of sex hormone concentrations with muscle mass and physical performance in older men. METHODS: We studied 477 community dwelling men, ages 78-97 years, who participated in the Osteoporotic Fractures in Men (MrOS) study. Follow-up measures were obtained in 247 men after 6 years. Testosterone, estradiol, estrone and dihydrotestosterone (DHT) were measured at the first visit by liquid chromatography/mass spectrometry, free testosterone by equilibrium dialysis, and sex hormone binding globulin (SHBG) by radioimmunoassay. Muscle mass was measured via D3-Cr dilution, and lean body mass via DXA. Grip strength, chair stands, 6m walk speed and Physical Activity Scale for the Elderly (PASE) were measured using standard methods. RESULTS: In a cross-sectional multivariable joint model including total testosterone, estradiol and SHBG, higher total testosterone was associated with higher D3Cr muscle mass and higher DXA appendicular lean mass while lower SHBG was associated with higher D3Cr muscle mass. In joint mixed effects models including total testosterone, estradiol and SHBG simultaneously, higher total testosterone was associated with less decline in grip strength, walking speed, and chair stand performance during follow-up. CONCLUSIONS: In both cross-sectional and longitudinal analysis in older men, joint modeling of sex hormones revealed positive associations between total testosterone and various measures of muscle mass, physical performance and strength.