A number of studies have shown that ingestion of crystalline amino acids, in particular branched chain amino acids (BCAA) can affect endurance performance, markers of muscle damage, and possibly mental focus. It seems that the longer and lower intensity events are affected more by consumption of BCAA. This study will test the hypothesis that BCAA availability limits central fatigue (the feeling of tiredness). While various aspects of performance have been tested no study to date has tested multiple exercise, muscular, and mental performance aspects in a single study. Thus, the overall purpose of this study is to determine whether an amino acid supplement changes the mental and physical response to prolonged exercise versus a placebo (carbohydrate drink).