Acute Effects of Beta-Alanine on Exercise Performance Variables.

Abstract

Beta-Alanine (BA) is converted to carnosine which serves to lower acid levels in the muscle by acting as an intramuscular buffer to H+ ions. BA supplementation may increase carnosine synthesis in muscle, leading to reduced muscle fatigue with exercise. PURPOSE: To determine the effects of an acute dose of BA (4 grams, 30 min before testing) on muscular power, muscular endurance and aerobic performance. METHODS: 21 recreationally active men (24.5±1.5yrs, 1.8±0.1m, 79.2±9.3kg) and 15 women (25.7±2.2yrs, 1.6±.0.1m, 55.1±8.1kg) participated in a placebo controlled, double blind cross-over design study. Subjects were tested on 3 separate days with a 24-hour washout period between test visits. Visits consisted of 4 tests done in the following order: vertical jump on a jump mat, repetition of 70% leg press and chest press max until failure, and a 4-kilometer time trial (4km) on a cycle ergometer. The first testing visit established the 1-repetition maximum on the leg and chess press and familiarization with testing procedures. Subjects were randomized to BA or placebo on the 2nd and 3rd visit. Comparisons of the effects of BA and placebo on exercise test values were made using two-way ANOVA with repeated measures (p<0.05). RESULTS: BA showed a significant increase from baseline in the number of reps performed on both the leg press (15.7±5.5 vs. 22.9±7.3 repetitions, p<0.001) and chest press (12.0±5.8 vs. 17.7±5.4 repetitions, p<0.001). Placebo showed a small non-significant increase from baseline in the number of reps performed on both the leg press (15.7±5.5 vs. 17.3±5.3 repetitions, p=0.055) and chest press (12.0±5.8 vs. 12.6±5.6 repetitions, p=0.059). The increases in the BA group were statistically different from the change in the placebo group (leg press, p<0.001 and chest press p<0.001). BA showed a significant increase from baseline in aerobic power (132.0±49.1 vs 144.0±48.8 Watts, p<0.001) during the 4km. Placebo showed a small non-significant increase from baseline in aerobic power (132.0±49.1 vs 134.3±49.4 Watts, p=0.080) during 4km. The increase in aerobic power in the BA group was statistically different from the change in the placebo group (p<0.001). CONCLUSION: A single 4 gram dose of BA improves muscular endurance and aerobic power in recreationally active young men and women.