Effect of Carbohydrate and Glucogenic Amino Acid Supplementation on Self-Paced Intermittent Running Performance

This study compared the effects of carbohydrate (CHO) and glucogenic amino acid (MIX) supplementation to those of isocaloric CHO supplementation on self-paced intermittent running performance. In a randomized crossover design, eight males completed two experimental trials (MIX or CHO) comprising 45 min of self-paced intermittent running on a non-motorized treadmill. Intermittent running consisted of a 15-s walk at 10% effort, 30-s jog at 45% effort, 25-s run at 75% effort, 16-s rest, and 4-s sprint at 100% effort; cycles were repeated over 45 min. Participants consumed a commercially available jelly drink containing either MIX (0.13 g·kg-1 alanine, 0.01 g·kg-1 proline, and 1.11 g·kg-1 CHO) or CHO (1.25 g·kg-1) 10 min before commencing intermittent running. The distance covered in sprints during the first 15 min was significantly higher in MIX than in CHO (p=0.043, d=0.32). The total distance covered were comparable between the trials (p>0.05). The blood lactate concentration at the end of the first 15 min was significantly lower in MIX than in CHO (p=0.008, d=0.78). Throughout the exercise, the blood glucose concentration was significantly lower in MIX than in CHO (p=0.049, d=1.16). There were no significant differences in heart rate, dehydration rate, or rating of perceived exertion during exercise between the trials (p>0.05). Alanine and proline combined with CHO supplementation increased sprint performance in the initial part of self-paced intermittent running compared with isocaloric CHO supplementation. However, this supplementation did not increase the total distance covered during the self-paced intermittent running.