Carb-Protein Drink Increases Carb Burning in Second Workout
Researchers from the University of Bath, England, Loughborough University and Queen's Medical College recently compared the effects of a carbohydrate recovery drink (CHO) and a carbohydrate-protein recovery drink (CHO-PRO) on muscle glycogen resynthesis between two long run workouts undertaken on the same day and on carbohydrate oxidation in the second workout.
Six runners ran for 90 minutes at 70 percent VO2max, rested for four hours, and then ran one hour at the same intensity. During the recovry period they drank either CHO or CHO-PRO. After a 14-day washout period, the runners repeated the protocol, but those who drank CHO the first time drank CHO-PRO instead and vice versa. The researchers found that CHO-PRO produced a greater insulin response during the recovery period, but rates of glycogen resynthesis were the same with the two drinks. Whole-body carbohydrate oxidation was significantly greater in the second run after CHO-PRO was consumed (48.4 vs. 41.7 mg.kg.min), but the rate of muscle glycogen use was the same, indicating that runners relied on blood glucose, liver glycogen and/or exogenous carbohydrate more after drinking CHO-PRO.
These results suggested that if the second run at been a maximal one-hour effort, the runners might have performed better after drinking CHO-PRO, as higher rates of crbohydrate oxidation allow higher rates of muscle work. The authors of this study, which was published in Medicine & Science in Sports & Exercise, did not make this speculation, however, concluding only that "the inclusion of protein in a carbohydrate-recovery supplement can increase the oxidation of extramuscular carbohydrate sources during subsequent exercise without altering the rate of muscle glycogen degradation." |