McGregor, S. J., Snyder, A. R., & Pizza, F. X. (2000). Herbal supplementation in highly trained cyclists during a period of intensified competition. Medicine and Science in Sports and Exercise, 32(5), Supplement abstract 465.

Highly trained cyclists (N = 10) used a supplement containing Tribulus terrestris and iprifalvone or a placebo for 38 days to determine if performance would be altered. Ss were matched and assigned to a treatment or placebo group. Training was normal for 23 days and from day 26 to 36, intense racing was experienced.

During performance trials, average power, VO2, and RER were similar. The experimental group improved in performance time over the study period whereas the placebo group did not. The free testosterone to cortisol ratio improved, mainly due to a lower cortisol concentration.

Implication. Tribulus terrestris and iprifalvone supplementation improved hormonal markers of overstrain as well as performance in highly trained cyclists.

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