Effect of Branched-Chain Amino Acid Supplementation on O2 Uptake Kinetics and Time to Exhaustion in Trained Women

Objective The aim of this study was to investigate the effect of Branched-Chain Amino Acid (BCAA) supplementation on O2 uptake kinetics and the time to exhaustion in trained women.  Methods In this quasi-experimental study with pre-test/post-test design, participants were 20 trained women (Mean±SD age, 21.3±0.5 years). They were randomly assigned into two groups of BCAA (received 45mg/kg/d BCAA for 7 days; n=10) and isocaloric placebo (received 2g/d microcrystalline cellulose for 7 days; n=10). On day 7, subjects performed the incremental exercise test on a cycle ergometer until exhaustion in order to measure maximal oxygen uptake (Vo2max). Respiratory gas exchange was measured using breath-by-breath analysis in order to evaluate O2 uptake kinetics. Data were analyzed using one-way ANOVA with repeated measures at the significance level of P<0.05. Results BCAA supplementation significantly increased Vo2max (P<0.04, 1.5±0.8 vs 1.9±0.5 min) and the time to exhaustion (P<0.02, 13.5±3.1 vs. 16.6±2.1 min) during the exercise test. The O2 uptake kinetics such as oxygen deficit (P<0.01), time constant 1(P<0.02) and time constant 2 (P<0.01) in the BCAA group were faster than those in the placebo group.  Conclusion BCAA supplementation (45mg/kg/d) can speed up the O2 uptake kinetics and may be effective in increasing the endurance capacity.