Traustadóttir T, et al. - Researchers performed a double-blind, randomized, placebo-controlled, parallel-group trial (Testosterone’s Effects on Atherosclerosis Progression in Aging Men) to determine the impacts of testosterone supplementation on peak oxygen uptake (V?O₂peak) during incremental cycle ergometry. Participants in the study were healthy men aged ≥ 60 years with total testosterone levels of 100 to 400 ng/dL or free testosterone levels < 50 pg/mL. As compared to men receiving placebo, the mean 3-year change in V?O₂peak was significantly smaller in men treated with testosterone and was correlated with increases in hemoglobin. The difference in V?O₂peak change between groups might show lessening of its expected age-related decline.