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目的 :探讨运动前进食不同血糖指数食物对长跑能力的影响。方法 :实验设计采用平衡重复测试法 ,8名男子耐力长跑运动员在间隔期不少于 7天内 ,在隔夜空腹情况下分别进食含相等热量的低血糖指数 [Glycemicindex (GI) ](GI =37)或高GI(GI =77)的碳水化合物 (CHO)食物 (CHO∶1 5g/kg体重 )。 2小时后 ,受试者在水平跑台上进行 2 1km的长跑能力测试。首 5km中 ,受试者以其 70 %VO2 max的速度跑步 ,而其后的 16km ,则可随意选择速度以最短时间完成。结果 :与高GI试验相比 ,所有受试者在进食低GI食物后的跑步时间明显缩短 (98 7± 2 0vs 10 1 5± 2 1min ,P<0 0 1)。整个跑步全程中 ,低GI试验的血糖及血清游离脂肪酸 (FFA)的水平较高GI试验为高。虽然进食高GI食物后两小时的血清胰岛素较高 ,但在运动过程中 ,血清胰岛素、皮质醇、血乳酸水平与低GI试验相比均无显著差异。与高GI试验相比 ,低GI试验中CHO氧化在能量供应上的依赖低 9 5 % ,而脂肪氧化则高 17 9%。结论 :在运动前 2小时进食低血糖指数的CHO食物 ,比提供同等热量的高血糖指数食物能更有效地提高长跑运动的能力。
Objective: To investigate the effect of eating different foods with glycemic index before exercise on long-distance running ability. METHODS: The experimental design consisted of a balanced repetitive test. Eight men’s endurance runners ate the Glycemic index (GI) (GI = 37) with equal calories for an overnight fasting interval of not less than 7 days, respectively. Or high GI (GI = 77) carbohydrate (CHO: 5 g / kg body weight). Two hours later, the subjects ran a 21 km long distance running test on a horizontal running stage. In the first 5 km, the subject ran at 70% of VO2 max, while the next 16 km was arbitrarily selected at the fastest speed. RESULTS: All subjects had significantly shorter run times (98 7 ± 20 vs 10 15 ± 21 min, P <0.01) after eating low GI foods compared to the high GI test. Throughout the entire run, high GI blood glucose and serum free fatty acids (FFA) levels were high in the low GI trial. Although serum insulin levels were high at two hours after eating high GI foods, there was no significant difference in serum insulin, cortisol, and blood lactate levels during exercise compared to the low GI test. Compared with the high GI test, the CHO oxidation in the low GI test was 95% lower in energy supply and 17 9% higher in fat oxidation. CONCLUSIONS: CHO foods with low glycemic index 2 hours prior to exercise more effectively improved long-distance motivation than food with the same caloric high glycemic index.