Postexercise Muscle Glycogen Recovery is Enhanced With a Carbohydrate-Protein Supplement

Abstract

0286 PURPOSE: This study examined whether a liquid carbohydrate-protein (C+P) supplement ingested early during recovery would enhance muscle glycogen resynthesis vs a liquid carbohydrate (CHO) supplement or an isoenergetic solid meal ingested later during recovery (PLB). METHODS: Two h after a standardized breakfast (7.0kcal/kg; 0.3g/kgP, 1.2g/kgC, 0.1g/kgF), six subjects cycled as intensely as possible for 60-min (AMex) and distance traveled was recorded. PRE- and POST-exercise, vastus lateralis muscle glycogen was determined using nuclear magnetic resonance spectroscopy. Immediately, 1h, and 2h post-exercise, subjects ingested liquid C+P (4.8kcal/kg; 0.8g/kgC, 0.4g/kgP), liquid CHO (4.8kcal/kg; 1.2g/kgC), or liquid PLB (no energy). 4h post-exercise a meal (solid food) was consumed (C+P and CHO received a meal identical to breakfast while PLB received 21kcal/kg; 1g/kgP, 3.6g/kgC, 0.3g/kgF). Total energy intake during the 6h recovery period was identical for all conditions. 6-h post-exercise, subjects repeated the same cycling protocol (PMex). Treatments were systematically rotated and the design, repeated. RESULTS: Among groups, muscle glycogen use was similar during AMex (−42.75±5.24 mmol/L C+P,−39.08±7.59 mmol/L CHO,−53.78±11.59 mmol/L PLB) and PMex (−38.40±4.37 mmol/L C+P,−31.16±3.78 mmol/L C,−40.33±1.47 mmol/L PLB); however, AMex > PMex. During the 6h recovery, muscle glycogen resynthesis was greater in C+P (+28.62±2.10 mmol/L) vs either CHO (+22.20±1.19 mmol/L, p<0.05) or PLB (+18.50±7.67 mmol/L, p<0.01). Despite these differences, cycling performance was similar for all treatments (AMex; 37.61±0.63km C+P, 37.03±0.60km CHO, 37.24±0.34km PLB and PMex; 36.31±0.83km C+P, 36.38±0.80km C, 35.34±0.45km PLB). CONCLUSIONS: Liquid C+P given early in recovery enhances 6h glycogen resynthesis relative to CHO or PLB; however, with cycling of this duration and intensity, muscle glycogen may not be the critical determinant of performance. Supported by The Joe Weider Foundation, Met-Rx USA, Inc., Biotest Laboratories LLC, and Kellogg Canada.