Effects of Anabolic-Androgenic Steroids on Muscular Strength

Abstract

To assess the effects of anabolic-androgenic steroids on human muscle strength. A MEDLINE search for the period from January 1966 to April 1990, supplemented by manual searches of previous reviews, produced 30 studies in which subjects received more than one dose of the study steroid and in which changes in muscular strength were measured. Of the 30 studies, 14 were not included in the detailed data summary because they did not use a placebo control, did not randomize subjects to groups, or did not make objective strength measurements, or because percent change in strength data could not be abstracted. Details of study design, reporting of results, and the adequacy and correctness of statistical methods were tabulated. Percent improvement in strength for the largest muscle group studied was computed, using the difference between results for the placebo and for the steroid-treated groups. Previously trained athletes show slightly greater improvements in strength in the anabolic-androgenic steroid-treated group than in the placebo group, with a median difference of 5% across the nine studies (range, 1.2% to 18.7%). A meta-analysis of the three studies with enough information to compute effect size showed a mean difference of 1.0 standard deviations (95% CI, 0.49 to 1.5). However, the poor overall quality of the studies in terms of design, sample size, and analysis; the lack of a dose-response effect across the narrow range of dosages tested; and the tendency for differences to be smaller in the larger studies throw these results into question. No evidence was found to support enhanced muscle strength with steroid use in eight studies in untrained normal volunteers. Anabolic steroids may slightly enhance muscle strength in previously trained athletes. No firm conclusion is possible concerning the efficacy of anabolic steroids in enhancing overall athletic performance. Results for the low steroid dosages studied in the published reports cannot be generalized to steroid-using athletes taking megadose regimens.