Arm crank power and hyperammonemia in response to L-aspartic acid supplementation.

摘要

Purpose. To examine the effect of L-Aspartic Acid (L-Asp) supplementation on short-term arm-crank power (i.e. W·min −1) and exercise-induced hyperammonemia in two gender-specific investigations. Methods. The male investigation (MALE) used nine highly-trained intercollegiate water polo players (WP) and nine moderately-trained college students (MOD); the female investigation (FEM) used 18 recreationally-trained college students. All exercised to exhaustion on two occasions following counterbalanced double-blind ingestion of 12.5g x 2 of L-Asp or placebo (P). The warm-up phase began at 25 W·min−1 and increased in 25 W·min −1 stages every 30 seconds (constant 100 rpm). Performance began (i.e. the subjects turned the crank ‘as fast as possible for as long as possible’) with stage completion of rating of perceived exertion of 17 (6–20 scale) in MOD and FEM and at the 4-minute mark (200 W·min −1) for WP. Individual warm-up time in session 1 for MOD and FEM was used as warm-up time for session 2, respectively. Venous blood samples were drawn at 3 minutes post-exercise and assayed for blood NH₃ [μM/L]. A 2 x 2 ANOVA with repeated measures was used for MALE, and a one-way ANOVA with repeated measures for FEM, with Tukey's t-test for post hoc differences. Results. Blood NH₃ [μM/L] decreased with L-Asp (vs. P) in WP (241.0 ± 18.4 vs. 200.6 ± 20.5, p 0.01) and MOD (219.7 ± 20.8 vs. 185.6 ± 27.5, p 0.05). Performance power (W·min−1) with L-Asp improved (p 0.01) in WP (270.2 ± 19.7 vs. 227.6 ± 14.3) but not (p > 0.05) in MOD (220.1 ± 9.1 vs. 204.4 ± 8.3). There was no treatment effect in FEM. Conclusion. These results suggest that 12.5 g x 2 QD of L-Asp reduces hyperammonemia and enhances short-term power in intercollegiate water polo players. Conversely, in MOD and FEM, 12.5 g x 2 QD of L-Asp does not attenuate exercise-induced hyperammonemia sufficiently to improve power.