Influence of post-exercise carbohydrate-protein ingestion on muscle glycogen metabolism in recovery and subsequent running exercise

We examined whether carbohydrate-protein ingestion influences muscle glycogen metabolism during short-term recovery from exhaustive treadmill running and subsequent exercise. Six endurance-trained individuals underwent two trials in a randomised double-blind design, each involving an initial run-to-exhaustion at 70% (Run-1) followed by 4-h recovery (REC) and subsequent run-to-exhaustion at 70% (Run-2). Carbohydrate-protein (CHO-P; 0.8 g carbohydrate·kg body mass [BM-1]·h-1 plus 0.4 g protein·kg BM-1·h-1) or isocaloric carbohydrate (CHO; 1.2 g carbohydrate·kg BM-1·h-1) beverages were ingested at 30-min intervals during recovery. Muscle biopsies were taken upon cessation of Run-1, post-recovery and fatigue in Run-2. Time-to-exhaustion in Run-1 was similar with CHO and CHO-P (81±17 and 84±19 min, respectively). Muscle glycogen concentrations were similar between treatments after Run-1 (99±3 mmol·kg dry mass [dm-1]). During REC, muscle glycogen concentrations increased to 252±45 mmol·kg dm-1 in CHO and 266±30 mmol·kg dm-1 in CHO-P (p= 0.44). Muscle glycogen degradation during Run-2 was similar between trials (3.3±1.4 versus 3.5±1.9 mmol·kg dm-1·min-1 in CHO and CHO-P, respectively) and no differences were observed at the respective points of exhaustion (93±21 versus 100±11 mmol·kg dm-1·min-1; CHO and CHO-P, respectively). Similarly, time-to-exhaustion was not different between treatments in Run-2 (51±13 and 49±15 min in CHO and CHO-P, respectively). Carbohydrate-protein ingestion equally accelerates muscle glycogen resynthesis during short-term recovery from exhaustive running as when 1.2 g carbohydrate·kg BM-1·h-1 are ingested. The addition of protein did not alter muscle glycogen utilisation or time to fatigue during repeated exhaustive running.