Title: The Influence of Carbohydrate-Protein Mixtures on Recovery of Endurance Capacity
Abstract: 0289 Recovery of endurance capacity following depletion of muscle glycogen is dependent on the degree of glycogen resynthesis, a process facilitated by insulin. Addition of protein to a carbohydrate solution appears to stimulate an increased insulin response, which may promote a greater rate of glycogen storage. PURPOSE: The aim of this study was to determine whether the ingestion of a carbohydrate-protein solution elicits a more rapid recovery of endurance capacity when compared with a carbohydrate solution alone. METHODS: Seven recreationally active men (age, 22 ± 0.2 yr; body mass, 83.5 ± 4.4 kg; VO2 max, 55 ± 1.5 ml.kg−1 min−1: mean ± SEM) participated in 2 trials, separated by 7 days, in which a glycogen lowering run (90 min @ 70% VO2 max) was followed by a 4 hour recovery. During recovery, either a 9.3% carbohydrate solution (CHO) or a 9.3% carbohydrate drink plus 1.5% protein (CHO-PRO) was ingested at 30 min intervals in volumes providing 0.8 g CHO.kg−1 body mass.h−1. Recovery of endurance capacity was then assessed by run time to exhaustion @ 85% VO2 max. RESULTS: During recovery, the serum insulin response was higher (p<0.01) and the plasma glucose response was lower (p<0.05) following CHO-PRO than after the CHO ingestion. However, there were no differences in the run times to exhaustion between the CHO-PRO (22.8 ± 2.8 min) and CHO (23.9 ± 5.3 min) trials. CONCLUSION: Despite greater insulin concentrations and a lower glucose response during recovery in the CHO-PRO trial, there were no differences between trials in endurance capacity during subsequent exercise. These results may suggest that factors other than carbohydrate availability contributed to the onset of fatigue.