Moodley D, Noakes T D, Bosch A N, Hawley J A, Schall R, Dennis S C
Department of Physiology, University of Cape Town Medical School Observatory, South Africa.
Eur J Appl Physiol Occup Physiol. 1992;64(4):328-34. doi: 10.1007/BF00636220.
We studied rates of exogenous carbohydrate (CHO) oxidation during 90 min of cycling exercise in trained cyclists exercising at 70% of maximal oxygen consumption (VO2max) when they ingested glucose, sucrose, or glucose polymer solutions at concentrations of 7.5%, 10% or 15%. Drinks were labelled with [U-14C]glucose or sucrose and were ingested at a rate of 100 ml.10 min-1. Rates of oxidation of the ingested CHO were calculated from the specific radio-activity of the labelled CHO, expired 14CO2 and carbon dioxide output (VCO2). Total CHO oxidation, determined from oxygen consumption and VCO2 was not influenced by CHO type or concentration. Gastric emptying (P = 0.01) and the rate of exogenous CHO oxidation (P = 0.028) was greatest for the glucose polymer solutions, and least for glucose. Although gastric emptying (P = 0.006) decreased with increasing CHO concentration, CHO delivery to the intestine and exogenous CHO oxidation increased linearly with increasing CHO concentration. The percentage of the CHO delivered to the intestine that was oxidized ranged from 30.0% for 7.5% CHO to 38.1% for 15% CHO. Our results indicated that the rate of gastric emptying for CHO was not controlled to provide a constant rate of energy delivery as is commonly believed and that factors subsequent to gastric emptying limit the rate of exogenous CHO oxidation from the ingested solution.
我们研究了训练有素的自行车运动员在以最大耗氧量（VO2max）的70%进行90分钟骑行运动时，摄入浓度为7.5%、10%或15%的葡萄糖、蔗糖或葡萄糖聚合物溶液后外源碳水化合物（CHO）的氧化速率。饮料用[U-14C]葡萄糖或蔗糖标记，以100 ml·10 min-1的速率摄入。根据标记CHO的比放射性、呼出的14CO2和二氧化碳排出量（VCO2）计算摄入CHO的氧化速率。由耗氧量和VCO2确定的总CHO氧化不受CHO类型或浓度的影响。葡萄糖聚合物溶液的胃排空率（P = 0.01）和外源CHO氧化速率（P = 0.028）最高，葡萄糖的最低。尽管胃排空率（P = 0.006）随CHO浓度增加而降低，但CHO向肠道的输送量和外源CHO氧化量随CHO浓度增加呈线性增加。输送到肠道的CHO中被氧化的百分比范围为7.5% CHO时的30.0%至15% CHO时的38.1%。我们的结果表明，CHO的胃排空率并非如通常所认为的那样受到控制以提供恒定的能量输送速率，并且胃排空后的因素限制了摄入溶液中外源CHO的氧化速率。
