Rhodiola and ginkgo combination boosts endurance (no training required)

Supplementation with extracts of Ginkgo biloba and Rhodiola crenulata increases the stamina of young men. This is shown in a human study published in 2009 in the Chinese Journal of Integrative Medicine.

Study
The researchers, at the University of Hong Kong, divided 67 young men into 2 groups. For 7 weeks, they gave the men in one group placebo capsules and the men in the other group capsules containing extracts of Ginkgo biloba and Rhodiola crenulata in a ratio of 1: 9.

The men took 4 capsules each day, each containing 270 milligrams of extract mixture. They took 2 capsules with breakfast and 2 capsules with dinner.

Results
The supplement increased the men's stamina. The subjects in the experimental group managed to cycle longer, and that may have been due to the increase in their bodies' ability to absorb oxygen. [VO2max]

Supplementation did not affect the test subjects' testosterone levels, but it did prevent cortisol levels from rising after exercise. That may mean that the men recovered faster.

Conclusion
"The present findings have provided evidence supporting the use of Rhodiola crenulata and Ginkgo biloba combined supplement for improving the endurance performance by increasing oxygen consumption and protecting against fatigue", summarize the researchers.

According to Russian animal study, extracts from both plants improve endurance, albeit in different ways. [Bull Exp Biol Med. 2003 Dec;136(6):585-7.]