Abstract
Testosterone (T) administration (TA) increases serum T and fat-free mass (FFM). Although TA-mediated increases in FFM may enhance physical performance, the data are largely equivocal, which may be due to differences in study populations, the magnitude of change in serum T and FFM, or the performance metrics. This meta-analysis explored effects of TA on serum T, FFM, and performance. Association between increases in serum T and FFM were assessed, and if changes in serum T or FFM, study population, or the performance metrics affected performance was determined. A systematic review of double-blind randomized trials comparing TA versus placebo on serum T, FFM, and performance was performed. Data were extracted from 20 manuscripts. Effect sizes (ES) were assessed using Hedge’s g and a random effects model. Data are presented as ES (95% CI). No significant correlation between changes in serum T and FFM was observed (p=0.167). Greater increases in serum T, but not FFM, resulted in larger effects on performance. Larger increases in testosterone [7.26(0.76,13.75)] and FFM [0.80(0.20,1.41)] were observed in young males, but performance only improved in diseased [0.16(0.05,0.28)] and older males [0.19(0.10,0.29)]. TA increased lower body [0.12(0.07,0.18)], upper body [0.26(0.11,0.40)], and handgrip [0.13(0.04,0.22)] strength, lower body muscular endurance [0.38(0.09,0.68)], and functional performance [0.20(0.00,0.41)], but not lower body power or aerobic endurance. TA elicits increases in serum T and FFM in younger, older and diseased males; however, the performance-enhancing effects of TA across studies were small, observed mostly in muscular strength and endurance, and only in older and diseased males.