Effect of anabolic steroids on new fiber formation and fiber area during stretch-overload.

The efficacy of anabolic steroid treatment to increase the extent of overload-induced new fiber formation and fiber hypertrophy was examined in anterior latissimus dorsi (ALD) muscles of Japanese quails. Adult quails were assigned to a control group (n = 20), which received stretch but no steroid (NS), or a stretch+steroid group (S), which received either nandrolone decanoate (n = 20) or testosterone enanthate (n = 12). Steroids were administered at 4.0 mg.kg body wt-1 x day-1. A weight corresponding to 10% of each bird's body weight was added to the right wing to effect a stretch of the right ALD. Thirty days of stretch-overload resulted in a 145.3 and 143.1% increase in total muscle weight of NS and S groups, respectively. Stretch-induced increases in nonmuscle tissue, fiber length, and new fiber formation were not altered by steroid administration. These results indicate that anabolic steroids did not act synergistically to enhance the extent of fiber hypertrophy or new fiber formation after 30 days of stretch-overload.