Anabolic-androgenic steroid administration causes hypertrophy of immobilized and nonimmobilized skeletal muscle in a sedentary rabbit model.

Although the use of anabolic agents in athletics has generated extensive publicity and controversy, the potential therapeutic benefits of these drugs have not been fully investigated. This randomized, blinded experimental study investigated whether short-term administration of an anabolic-androgenic steroid can limit immobilization-induced muscle atrophy in a rabbit model. We casted one hindlimb each in 48 New Zealand White rabbits and randomly assigned the rabbits to two groups. The treated group received weekly intramuscular injections of the anabolic-androgenic steroid, nandrolone decanoate (15 mg/kg). Immobilization significantly decreased muscle weights in both the treated rabbits and controls. Compared with controls, the body weights of the treated rabbits increased significantly at 2, 4, and 8 weeks. At 4 and 8 weeks, wet weights, dry weights, and contractile forces were significantly greater in both the casted and noncasted tibialis anterior muscle-tendon units of the treated group. Dry weights and casted contractile forces of the extensor digitorum longus muscle unit at 4 weeks and all measures at 8 weeks were greater in the treated rabbits than in controls. These results are contrary to previously accepted views that anabolic-androgenic steroid use leads to muscle hypertrophy only in conjunction with strength training. This study adds to the growing evidence that anabolic-androgenic steroids can produce significant skeletal muscle hypertrophy in sedentary populations.