Effects of testosterone supplementation for 3 years on muscle performance and physical function in older men

Context: Findings of studies of testosterone's effects on muscle strength and physical function in oldermen have been inconsistent; its effects onmuscle power and fatigability have not been studied. Objective: To determine the effects of testosterone administration for 3 years in older men on muscle strength, power, fatigability, and physical function. Design, Setting, and Participants: This was a double-blind, placebo-controlled, randomized trial of healthy men ≥60 years old with total testosterone levels of 100 to 400 ng/dL or free testosterone levels <50 pg/mL. Interventions: Random assignment to 7.5 g of 1% testosterone or placebo gel daily for 3 years. Outcome Measures: Loaded and unloaded stair-climbing power, muscle strength, power, and fatigability in leg press and chest press exercises, and lean mass at baseline, 6, 18, and 36 months. Results: The groupswere similar at baseline. Testosterone administration for 3 yearswas associated with significantly greater performance in unloaded and loaded stair-climbing power than placebo (mean estimated between-group difference, 10.7W[95% confidence interval (CI),24.0 to 25.5], P = 0.026; and 22.4 W [95% CI, 4.6 to 40.3], P = 0.027), respectively. Changes in chest-press strength (estimated mean difference, 16.3N;95%CI, 5.5 to 27.1; P<0.001) and power (mean difference 22.5W;95%CI, 7.5 to 37.5; P < 0.001), and leg-press power were significantly greater in men randomized to testosterone than in those randomized to placebo. Lean body mass significantly increased more in the testosterone group. Conclusion: Comparedwith placebo, testosterone replacement in oldermen for 3 yearswas associated with modest but significantly greater improvements in stair-climbing power, muscle mass, and power. Clinical meaningfulness of these treatment effects and their impact on disability in older adults with functional limitations remains to be studied.