Effects Of Supplementation With Branched Chain Amino Acids On Fatigue In Rats Subjected To Swimming

Abstract

1179 The fatigue process during prolonged exercise can involve mechanisms related to muscle (peripheral fatigue) and/or central nervous system (central fatigue). The development of dietary manipulation, such as branched chain amino acids (BCAA) supplementation, may represent an alternative to delay such mechanisms and to improve the performance during exercise. Objective: The present work aims to evaluate the effect of diets supplemented with two different concentrations of BCAA on the fatigue mechanisms of rats subjected to swimming in a chronic study. Methods: Male Wistar rats (240g initial weight) were divided in six groups of six animals. In the day of the sacrifice, half of the groups (3 groups of 6 rats) exercised for 1 hour and the other groups exercised until exhaustion. The rats were subjected to 3 different diets: control diet (CD) elaborated in accordance to the American Institute of Nutrition (AIN-93M) recommendations, diet supplemented with 50% BCAA (DS1) and diet supplemented with 100% more BCAA than the AIN-93M recommendations. (DS2). Swimming training was made for 6 weeks: 1 hour a day, 5 days a week, with overload close to the anaerobic threshold attached to the tail (about 6% of the body weight). On the last day of the protocol half of each group was killed after 1h swimming or after the exhaustion test. Results: There was no significant statistical difference (p = 0.273) among the groups concerning the swimming time to reach exhaustion. However, the groups subjected to the exhaustion test, when compared to the 1h swimming groups, presented lower concentrations of blood glucose (p<0.001), muscle glycogen (p<0.001), hepatic glycogen (p<0.001) and higher concentrations of blood ammonia (p<0.001), serum cortisol (p<0.001) and blood lactate (p<0.001). In relation to the effects of the supplementation, preservation of the muscle (p<0.001) and hepatic (p<0.001) glycogen was observed on the 1h swimming groups. In these groups, the blood ammonia concentration was higher in the DS2 groups when compared to the DC e DS1 groups (p<0.001). Conclusion: The BCAA supplementation showed no positive influence over performance in this exercise intensity despite the hepatic glycogen preservation.