Wee Shiou-Liang, Williams Clyde, Tsintzas Kostas, Boobis Leslie
School of Sport and Exercise Sciences, Loughborough University, Loughborough, Leicestershire LE11 3TU, UK.
J Appl Physiol (1985). 2005 Aug;99(2):707-14. doi: 10.1152/japplphysiol.01261.2004. Epub 2005 Apr 14.
The aim of this study was to compare the effect of preexercise breakfast containing high- and low-glycemic index (GI) carbohydrate (CHO) (2.5g CHO/kg body mass) on muscle glycogen metabolism. On two occasions, 14 days apart, seven trained men ran at 71% maximal oxygen uptake for 30 min on a treadmill. Three hours before exercise, in a randomized order, subjects consumed either isoenergetic high- (HGI) or low-GI (LGI) CHO breakfasts that provided (per 70 kg body mass) 3.43 MJ energy, 175 g CHO, 21 g protein, and 4 g fat. The incremental areas under the 3-h plasma glucose and serum insulin response curves after the HGI meal were 3.9- (P < 0.05) and 1.4-fold greater (P < 0.001), respectively, than those after the LGI meal. During the 3-h postprandial period, muscle glycogen concentration increased by 15% (P < 0.05) after the HGI meal but remained unchanged after the LGI meal. Muscle glycogen utilization during exercise was greater in the HGI (129.1 +/- 16.1 mmol/kg dry mass) compared with the LGI (87.9 +/- 15.1 mmol/kg dry mass; P < 0.01) trial. Although the LGI meal contributed less CHO to muscle glycogen synthesis in the 3-h postprandial period compared with the HGI meal, a sparing of muscle glycogen utilization during subsequent exercise was observed in the LGI trial, most likely as a result of better maintained fat oxidation.
本研究的目的是比较含有高血糖指数（GI）和低血糖指数碳水化合物（CHO）（2.5克CHO/千克体重）的运动前早餐对肌肉糖原代谢的影响。14天内分两次，7名训练有素的男性在跑步机上以71%的最大摄氧量跑30分钟。运动前3小时，受试者以随机顺序食用等能量的高GI（HGI）或低GI（LGI）CHO早餐，这些早餐（每70千克体重）提供3.43兆焦能量、175克CHO、21克蛋白质和4克脂肪。HGI餐餐后3小时血浆葡萄糖和血清胰岛素反应曲线下的增量面积分别比LGI餐餐后大3.9倍（P<0.05）和1.4倍（P<0.001）。在餐后3小时内，HGI餐餐后肌肉糖原浓度增加了15%（P<0.05），而LGI餐餐后则保持不变。与LGI试验（87.9±15.1毫摩尔/千克干质量；P<0.01）相比，HGI试验中运动期间肌肉糖原利用率更高（129.1±16.1毫摩尔/千克干质量）。尽管与HGI餐相比，LGI餐在餐后3小时内对肌肉糖原合成的CHO贡献较少，但在LGI试验中观察到后续运动期间肌肉糖原利用率有所节省，这很可能是由于脂肪氧化得到更好维持的结果。
