Low testosterone levels and decline in physical performance and muscle strength in older men: findings from two prospective cohort studies.

OBJECTIVE Progressive declines in serum levels of testosterone parallel the decline in physical performance and muscle strength in ageing men, although findings are not conclusive. We examined whether levels of testosterone were associated with 3-year decline in physical performance and muscle strength in older men. DESIGN Longitudinal data were available for 486 men (mean age 74.9 years, SD 6.4) from the Longitudinal Ageing Study Amsterdam (LASA) and 1071 well-functioning men (mean age 73.7 years, SD 2.8) from the Health, Ageing and Body Composition (Health ABC) study. MEASUREMENTS Three-year change in physical performance score and grip strength according to categories of total testosterone (TT) and free testosterone (FT) levels. RESULTS The mean 3-year change in physical performance was -1.1 (SD 2.7, -13.6%) in LASA and -0.3 (SD 1.5, -2.9%) in Health ABC. The mean 3-year change in grip strength was -9.7 kg (SD 12.2, -13.2%) in LASA and -4.4 kg (SD 11.4,-5.8%) in Health ABC. Low levels of TT were not associated with decline in physical performance or with decline in muscle strength [e.g. mean change in physical performance -1.09 (SD 0.26) in the lowest quartile (Q1) and -0.88 (0.24) in the highest quartile (Q4) of total testosterone in LASA, and -0.26 (0.07) vs.-0.36 (0.11) in Health ABC]. Similar results were found for FT. CONCLUSIONS Low levels of TT and FT were neither associated with 3-year decline in physical performance nor with 3-year decline in muscle strength in two independent samples of older men.