Thomas D E, Brotherhood J R, Brand J C
Department of Biochemistry, University of Sydney.
Int J Sports Med. 1991 Apr;12(2):180-6. doi: 10.1055/s-2007-1024664.
Low glycemic index (GI) foods may confer an advantage when eaten before prolonged strenuous exercise by providing a slow-release source of glucose to the blood without an accompanying insulin surge. To test this hypothesis, eight trained cyclists pedalled to exhaustion one hour after ingestion of equal carbohydrate portions of four test meals: lentils, a low GI food (LGI); potato, a high GI food (HGI), and glucose and water. Plasma glucose and insulin levels were lower after LGI than after HGI from 30 to 60 min after ingestion (p less than 0.05). Plasma free fatty acid (FFA) levels were highest after water (p less than 0.05) followed by LGI and then glucose and HGI. From 45 to 60 min after ingestion, plasma lactate was higher in the HGI trial than in the LGI trial (p less than 0.05) and remained higher throughout the period of exercise. The rank order from lowest to highest for total carbohydrate oxidation during exercise was water, lentils, glucose and potato. Endurance time was 20 min longer after LGI than after HGI (p less than 0.05). These findings suggest that a low GI pre-game meal may prolong endurance during strenuous exercise by inducing less post-prandial hyperglycemia and hyperinsulinemia, lower levels of plasma lactate before and during exercise, and by maintaining plasma glucose and FFA at higher levels during critical periods of exercise.
低血糖指数（GI）食物在长时间剧烈运动前食用时，可能具有一定优势，因为它能为血液提供缓慢释放的葡萄糖来源，且不会伴随胰岛素激增。为了验证这一假设，八名经过训练的自行车运动员在摄入四份测试餐中碳水化合物含量相等的食物后一小时，骑行至力竭：小扁豆，一种低血糖指数食物（LGI）；土豆，一种高血糖指数食物（HGI），以及葡萄糖和水。摄入后30至60分钟，LGI组的血浆葡萄糖和胰岛素水平低于HGI组（p<0.05）。饮用清水后血浆游离脂肪酸（FFA）水平最高（p<0.05），其次是LGI组，然后是葡萄糖组和HGI组。摄入后45至60分钟，HGI试验中的血浆乳酸水平高于LGI试验（p<0.05），且在整个运动期间一直较高。运动期间总碳水化合物氧化从低到高的顺序为水、小扁豆、葡萄糖和土豆。LGI组的耐力时间比HGI组长20分钟（p<0.05）。这些发现表明，赛前食用低血糖指数餐可能通过减少餐后高血糖和高胰岛素血症、降低运动前和运动期间的血浆乳酸水平，以及在运动关键期将血浆葡萄糖和FFA维持在较高水平，从而延长剧烈运动期间的耐力。
