The effects of acute and chronic oral tea catechins and ornithine supplementation on exercise-induced ammonia accumulation and cycling performance in healthy young men: a randomized, double-blind, cross-over, placebo-controlled trial.

Purpose: This study examined the effects of acute and chronic oral intake of tea catechins and ornithine supplementation on exercise-induced ammonia accumulation and cycling performance.

Methods: Sixteen healthy young men participated in a randomized, double-blind, cross-over, placebo-controlled study. For the acute trials, the participants consumed either tea catechins and ornithine (CO) or placebo (P) and performed cycling exercises at an intensity corresponding to 75% of the maximum heart rate for 60 min, followed by a 15-min cycling performance test. The participants continued to consume each designated supplement for 13 days. For the chronic trials, the participants repeated the same protocol as the acute trials on day 14. After a washout period, the participants changed the supplement and repeated the same protocol as above.

Results: Plasma catechins (acute ES = 3.61; chronic ES = 2.64, p < 0.001) and ornithine (acute ES = 4.28; chronic ES = 2.25, p < 0.001) concentrations were higher in both acute and chronic CO trials than those in P trials. No differences were found in plasma ammonia concentration measured during the whole experimental period and in mean power output during the performance test among trials. Subjective fatigue during 60-min cycling was lower in both acute and chronic CO trials than those in P trials (acute ES = 0.32, chronic ES = 0.60, p < 0.001).

Conclusions: A single dose and 14-day oral intake of tea catechins and ornithine supplementation did not suppress exercise-induced ammonia accumulation or enhance cycling performance.

Clinical trial: Clinical trial registration ID: UMIN000035267.