Muscle ultrastructure after strength training with placebo or anabolic steroid.

The influence of strength training on muscle fiber area, capillary ultrastructure, and capillary supply was studied in experienced male bodybuilders taking either anabolic steroids or a placebo. During 8 weeks, 13 subjects received a weekly injection of either placebo or nandrolone decanoate (starting dose 200 mg, followed by 100 mg weekly), in a double-blind, counterbalanced design. Before and after 8 weeks a needle biopsy was taken from the vastus lateralis muscle for studying morphometric characteristics of fibers and ultrastructure and morphometric characteristics of capillaries. The fiber cross-sectional area increased significantly only after steroid treatment. Capillary ultrastructure and capillary supply were not changed after the training period. In none of the measured parameters was any difference found between placebo and steroid treatment.