Effect of branched-chain amino acids (BCAA), glucose, and glucose plus BCAA on endurance performance in rats

Purpose: The purpose of this study was to assess the effects of pre-exercis e administration of branched-chain amino acids (BCAA), glucose, and glucose plus BCAA on time to exhaustion during treadmill exercise in rats. Methods : Wistar rats were injected intraperitoneally with 1 mL of saline (0.9% NaC l), BCAA (30 mg), glucose (100 mg), or glucose plus BCAA 5 min before eithe r 45 min of submaximal exercise (N = 32) or running to exhaustion (N = 24). After the submaximal exercise test, blood was collected for the measuremen t of ammonia, BCAA, free tryptophan (free TRP), glucose, free fatty acid, a nd lactic acid, and muscle samples were taken from the m. soleus for determ ination of glycogen content. Results: Mean run time to exhaustion was signi ficantly longer after BCAA administration (158 +/- 26 min) compared with th at after saline (118 +/- 35 min)(P < 0.05) but not compared with that after glucose administration (179 +/- 21 min). When glucose is administered befo re exercise, the supplementary administration of BCAA had no additional eff ect on performance (171 +/- 12 min). The data on blood ammonia, ratio of fr ee TRP/BCAA, and muscle glycogen did not provide a clue for explaining the higher endurance performance after BCAA supplementation. Conclusion: The re sults support the hypothesis that the effect of BCAA administration on perf ormance could be related to carbohydrate availability during exercise.