EFFECT OF COINGESTION OF FAT AND PROTEIN WITH CARBOHYDRATE FEEDINGS ON MUSCLE GLYCOGEN-STORAGE

Dietary guidelines for achieving optimal muscle glycogen storage after prolonged exercise have been given in terms of absolute carbohydrate (CHO) intake (8-10 g . kg(-1) . day(-1)). However, it is of further in terest to determine whether the addition of fat and protein to carbohy drate feedings affects muscle glycogen storage. Eight well-trained tri athletes [23.1 +/- 2.0 (SE) yr; 74.0 +/- 3.4 kg; peak O-2 consumption = 4.7 +/- 0.4 l/min] undertook an exercise trial (2 h at 75% peak O-2 consumption, followed by four 30-s sprints) on three occasions, each 1 wk apart. For 24 h after each trial, the subjects rested and were ass igned to the following diets in randomized order: control (C) diet(hig h glycemic index CHO foods; CHO = 7 g . kg(-1) . day(-1)), added fat a nd protein (FP) diet (C diet + 1.6 g . kg(-1) . day(-1) fat + 1.2 g . kg(-1) . day(-1) protein), and matched-energy diet [C diet + 4.8 g . k g(-1) . day(-1) additional CHO (Polycose) to match the additional ener gy in the FP diet]. Meals were eaten at t = 0, 4, 8, and 21 h of recov ery. The total postprandial incremental plasma glucose area was signif icantly reduced after the FP diet (P < 0.05). Serum free fatty acid an d plasma triglyceride responses were significantly elevated during the FP trial (P < 0.05). There were no differences between trials in musc le glycogen storage over 24 h (C, 85.8 +/- 2.7 mmol/kg wet wt; FP, 80. 5 +/- 8.2 mmol/kg wet wt; matched-energy, 87.9 +/- 7.0 mmol/kg wet wt) . Results of this study suggest that the addition of fat and protein t o a recovery diet does not alter glycogen storage over 24 h, provided CHO intake is adequate.