Kirwan J P, O'Gorman D, Evans W J
Noll Physiological Research Center, Pennsylvania State University, University Park 16802, USA.
J Appl Physiol (1985). 1998 Jan;84(1):53-9. doi: 10.1152/jappl.1998.84.1.53.
The purpose of this study was to determine whether presweetened breakfast cereals with various fiber contents and a moderate glycemic index optimize glucose availability and improve endurance exercise performance. Six recreationally active women ate 75 g of available carbohydrate in the form of breakfast cereals: sweetened whole-grain rolled oats (SRO, 7 g of dietary fiber) or sweetened whole-oat flour (SOF, 3 g of dietary fiber) and 300 ml of water or water alone (Con). The meals were provided 45 min before semirecumbent cycle ergometer exercise to exhaustion at 60% of peak O2 consumption (VO2peak). Diet and physical activity were controlled by having the subjects reside in the General Clinical Research Center for 2 days before each trial. Blood samples were drawn from an antecubital vein for glucose, free fatty acid (FFA), glycerol, insulin, epinephrine, and norepinephrine determination. Breath samples were obtained at 15-min intervals after meal ingestion and at 30-min intervals during exercise. Muscle glycogen concentration was determined from biopsies taken from the vastus lateralis muscle before the meal and immediately after exercise. Plasma FFA concentrations were lower (P < 0.05) during the SRO and SOF trials for the first 60 and 90 min of exercise, respectively, than during the Con trial. Respiratory exchange ratios were higher (P < 0.05) at 90 and 120 min of exercise for the SRO and SOF trials, respectively, than for the Con trial. At exhaustion, glucose, insulin, FFA, glycerol, epinephrine, and norepinephrine concentrations, respiratory exchange ratio, and muscle glycogen use in the vastus lateralis muscle were similar for all trials. Exercise time to exhaustion was 16% longer (P < 0.05) during the SRO than during the Con trial: 266.5 +/- 13 and 225.1 +/- 8 min, respectively. There was no difference in exercise time for the SOF (250.8 +/- 12) and Con trials. We conclude that eating a meal with a high dietary fiber content and moderate glycemic index 45 min before prolonged moderately intense exercise significantly enhances exercise capacity.
本研究的目的是确定含有不同纤维含量和中等血糖指数的预加糖早餐谷物是否能优化葡萄糖供应并改善耐力运动表现。六名有休闲运动习惯的女性以早餐谷物的形式摄入75克可利用碳水化合物：加糖的全谷物燕麦片（SRO，膳食纤维7克）或加糖的全燕麦粉（SOF，膳食纤维3克），并饮用300毫升水，或仅饮用清水（对照组）。在半卧位蹬车测力计运动至耗竭（达到峰值耗氧量（VO2peak）的60%）前45分钟提供这些餐食。在每次试验前，让受试者在综合临床研究中心居住2天，以控制饮食和身体活动。从前臂肘前静脉采集血样，用于测定葡萄糖、游离脂肪酸（FFA）、甘油、胰岛素、肾上腺素和去甲肾上腺素。在进食后每隔15分钟采集呼气样本，在运动期间每隔30分钟采集。在进食前和运动后立即从股外侧肌取活检样本，测定肌肉糖原浓度。在SRO和SOF试验中，运动的前60分钟和90分钟期间，血浆FFA浓度分别低于对照组（P<0.05）。在运动90分钟和120分钟时，SRO和SOF试验的呼吸交换率分别高于对照组（P<0.05）。在耗竭时，所有试验的葡萄糖、胰岛素、FFA、甘油、肾上腺素和去甲肾上腺素浓度、呼吸交换率以及股外侧肌的肌肉糖原利用情况相似。SRO试验的运动至耗竭时间比对照组延长了16%（P<0.05）：分别为266.5±13分钟和225.1±8分钟。SOF试验（250.8±12分钟）和对照组的运动时间没有差异。我们得出结论，在长时间中等强度运动前45分钟进食一顿膳食纤维含量高且血糖指数中等的餐食，可显著提高运动能力。
