Many older athletes take statins, which are known to have potential for muscle toxicity. The adverse effects of statins on muscles and the influence thereof on athletic performance remain uncertain. Coenzyme Q-10 (CoQ10) may improve performance and reduce muscle toxicity in older athletes taking statins. This trial was designed to evaluate the benefits of CoQ10 administration for mitochondrial function in this population. Twenty athletes aged ≥ 50 years who were taking stable doses of statins were randomized to receive either CoQ10 (200 mg daily) or placebo for 6 weeks in a double-blind, placebo-controlled, crossover study to evaluate the impact of CoQ10 on the anaerobic threshold (AT). Several secondary endpoints, including muscle function, cardiopulmonary exercise function, and subjective feelings of fitness, were also assessed. The mean (SD) change in AT from baseline was -0.59 (1.2) mL/kg/min during placebo treatment and 2.34 (0.8) mL/kg/min during CoQ10 treatment (P = 0.116). The mean change in time to AT from baseline was significantly greater during CoQ10 treatment than during placebo treatment (40.26 s vs 0.58 s, P = 0.038). Furthermore, muscle strength as measured by leg extension repetitions (reps) increased significantly during CoQ10 treatment, with a mean (SD) increase from baseline of 1.73 (2.9) reps during placebo treatment versus 3.78 (5.0) reps during CoQ10 treatment (P = 0.031). Many other parameters also tended to improve in response to CoQ10 treatment. Treatment with CoQ10 improved AT in comparison with baseline values in 11 of 19 (58%) subjects and in comparison with placebo treatment values in 10 of 19 (53%) subjects. Treatment with CoQ10 (200 mg daily) did not significantly improve AT in older athletes taking statins. However, it did improve muscle performance as measured by time to AT and leg strength (quadriceps muscle reps). Many other measures of mitochondrial function also tended to improve during CoQ10 treatment.