Every now and then some old or even ancient supplements are reborn by new research illustrating that they work in ways we could have never imagined, ginkgo biloba and rhodiola crenulata are two such supplements.
In an article published in the Chinese Journal of Integrative Medicine, scientists investigated the effects of ingesting a supplement stack consisting of Ginkgo Biolba and Rhodiola Crenulata on endurance performance, testosterone, and cortisol. In this large double-blinded, placebo and controlled trial, subjects ingested 2 supplement capsules or placebo twice per day (after breakfast and dinner) over the course of 7 weeks. Scientists assessed power output (using a Wingate test) and maximum oxygen uptake (VO2max, using a Bruce Treadmill Test) at baseline (before supplement ingestion) and end-point (after 7 weeks supplement ingestion). Furthermore, as an indication of training fatigue, blood was collected to assess serum cortisol and testosterone levels on each of the testing days.
The authors concluded that 7 weeks of supplementation significantly increased both absolute and relative VO2max, with no change in power output. Interestingly, those subjects who received the placebo had markedly greater cortisol levels and a decreased testosterone to cortisol ratio (signs of overtraining and catabolism); whereas, those who received Ginkgo Biolba and Rhodiola Crenulata had normal healthy cortisol and testosterone levels.
Zhang ZJ, Tong Y, Zou J, Chen PJ, Yu DH. Dietary supplement with a combination of Rhodiola crenulata and Ginkgo biloba enhances the endurance performance in healthy volunteers. Chin J Integr Med. 2009 Jun;15(3):177-83. Epub 2009 Jul 2.