We report on a randomized double-blind, placebo-controlled parallel-group study, which aimed to investigate the effects of ubiquinol on clinical parameters and physical performance of trained men. Twenty-nine trained men aged 20-30 years who had VO2max at least 40 ml/kg/min and performed 1RM bench press at least 1.0 times their own body weight were randomly assigned to receive either oral 200 mg daily ubiquinol or identical appearing placebo for a duration of 6 weeks. At the 6-week visit, ubiquinol group had significantly decreased body mass index, percent body fat, systolic and diastolic blood pressures (p=0.048, 0.043, 0.005, and 0.0024, respectively) and significantly increased VO2max (42.1±0.4 to 42.4±0.3 ml/kg/min) compared to the placebo group (p=0.011, respectively). In conclusion, daily oral intake of 200 mg ubiquinol supplementation for 6 weeks duration resulted in significantly improved clinical parameters and most importantly had greatly enhanced physical performance by increased aerobic capacity measured as VO2max in trained men