['To determine whether the ingestion of a herbal supplement called Rhodiola-Gingko Capsule (RGC) would enhance the endurance performance of healthy volunteers and change relevant hormones in a favorable manner.', 'Seventy healthy male volunteers (age ranges from 18 to 22 years old) were randomly assigned to RGC group (35 cases, each capsule containing 270 mg herbal extracts, 4 capsules per day) or placebo group (35 cases, equivalent placebo preparation) for 7 weeks using computer produced digital random method. The endurance performance, serum testosterone and cortisol levels were measured at the baseline and the endpoint.', 'Sixty-seven subjects (34 in the RGC group and 33 in the placebo group) completed a 7-week treatment. The RGC group displayed a significantly greater baseline-to endpoint increase in maximal oxygen uptake (VO(2max)) than placebo group in both absolute (P=0.020) and relative values (P=0.023). At the endpoint, the serum cortisol level was unchanged in the RGC group compared with the baseline, but it was significantly elevated in the placebo group (P<0.05). The endpoint ratio of testosterone to cortisol, a surrogate for overtraining and fatigue in endurance exercises, was also indifferent compared with the baseline in the RGC group, but significantly decreased in the placebo group (P<0.05).'] Does dietary supplement with a combination of Rhodiola crenulata and Ginkgo biloba enhance the endurance performance in healthy volunteers?