Bhasin S, Woodhouse L, Casaburi R, Singh AB, Bhasin D, Berman N, Chen X, Yarasheski KE, Magliano L, Dzekov C, Dzekov J, Bross R, Phillips J, Sinha-Hikim I, Shen R, Storer TW
American Journal of Physiology-Endocrinology and Metabolism
December 2001
RCT
61 participants
Abstract
Androgen use by athletes to enhance performance is driven by the assumption that their physiological effects are proportional to the administered dose. However, dose-response relationships in healthy young men have not been fully defined. We determined changes in fat-free mass, muscle size, strength, and power in response to weekly intramuscular injections of testosterone enanthate (25, 50, 125, 300, or 600 mg) for 20 wk in 61 healthy men 18-35 yr old. Fat-free mass increased dose dependently in men receiving 125, 300, or 600 mg of testosterone weekly. Changes in leg press strength, leg power, thigh and quadriceps muscle volumes were also significantly associated with testosterone dose. Sexual function, visual-spatial cognition and mood, red cell mass, and plasma HDL cholesterol showed dose-related responses.
Methodology
Randomized, double-blind, placebo-controlled trial lasting 20 weeks. Participants received GnRH agonist plus one of five doses of testosterone enanthate (25, 50, 125, 300, or 600 mg weekly). Measurements included body composition by underwater weighing and DEXA, muscle strength by one-repetition maximum testing, muscle power, and hormone levels.
Results
The changes in fat-free mass were significantly correlated with testosterone dose and total testosterone concentrations. Muscle strength and power increased dose-dependently. Thigh muscle volume increased significantly in a dose-dependent manner. Changes in leg press strength and power were highly correlated with changes in testosterone dose and concentration.
Conclusions
Changes in circulating testosterone concentrations result in dose-dependent changes in fat-free mass, muscle size, strength, and power in healthy young men.