Stevenson Emma J, Williams Clyde, Mash Laura E, Phillips Beth, Nute Maria L
Sport and Exercise Nutrition Research Group, School of Sport and Exercise Sciences, Loughborough University, Leicestershire, United Kingdom.
Am J Clin Nutr. 2006 Aug;84(2):354-60. doi: 10.1093/ajcn/84.1.354.
Few data exist on the metabolic responses to mixed meals with different glycemic indexes and their effects on substrate metabolism during exercise in women.
We examined the effects of preexercise mixed meals providing carbohydrates with high (HGI) or low glycemic index (LGI) on substrate utilization during rest and exercise in women.
Eight healthy, active, eumenorrheic women [aged 18.6 +/- 0.9 y; body mass: 59.9 +/- 7.1 kg; maximal oxygen uptake (VO(2)max): 48.7 +/- 1.1 mL . kg(-1) . min(-1)] completed 2 trials. On each occasion, subjects were provided with a test breakfast 3 h before performing a 60-min run at 65% VO(2)max on a motorized treadmill. Both breakfasts provided 2 g carbohydrate/kg body mass and were isoenergetic. The calculated GIs of the meals were 78 (HGI) and 44 (LGI).
Peak plasma glucose and serum insulin concentrations were greater after the HGI breakfast than after the LGI breakfast (P < 0.05). No significant differences in substrate oxidation were reported throughout the postprandial period. During exercise, the estimated rate of fat oxidation was greater in the LGI trial than in the HGI trial (P < 0.05). Similarly, plasma free fatty acid and glycerol concentrations were higher throughout exercise in the LGI trial (P < 0.05). No significant differences in plasma glucose or serum insulin were observed during exercise.
Altering the GI of the carbohydrate within a meal significantly changes the postprandial hyperglycemic and hyperinsulinemic responses in women. A LGI preexercise meal resulted in a higher rate of fat oxidation during exercise than did an HGI meal.
关于不同血糖指数的混合餐对女性代谢反应及其在运动期间对底物代谢影响的数据很少。
我们研究了运动前提供高血糖指数（HGI）或低血糖指数（LGI）碳水化合物的混合餐对女性休息和运动期间底物利用的影响。
八名健康、活跃、月经正常的女性[年龄18.6±0.9岁；体重：59.9±7.1千克；最大摄氧量（VO₂max）：48.7±1.1毫升·千克⁻¹·分钟⁻¹]完成了2项试验。每次试验时，受试者在电动跑步机上以65%VO₂max进行60分钟跑步前3小时食用一份测试早餐。两份早餐均提供2克碳水化合物/千克体重且能量相等。计算得出的餐食血糖指数分别为78（HGI）和44（LGI）。
HGI早餐后血浆葡萄糖和血清胰岛素浓度峰值高于LGI早餐后（P<0.05）。整个餐后期间底物氧化无显著差异。运动期间，LGI试验中估计的脂肪氧化速率高于HGI试验（P<0.05）。同样，LGI试验中整个运动过程血浆游离脂肪酸和甘油浓度更高（P<0.05）。运动期间血浆葡萄糖或血清胰岛素无显著差异。
改变餐食中碳水化合物的血糖指数会显著改变女性餐后高血糖和高胰岛素血症反应。运动前食用LGI餐比HGI餐在运动期间导致更高的脂肪氧化速率。
