Jeukendrup Asker E
Human Performance Laboratory, School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom.
Nutrition. 2004 Jul-Aug;20(7-8):669-77. doi: 10.1016/j.nut.2004.04.017.
It is generally accepted that carbohydrate (CHO) feeding during exercise can improve endurance capacity (time to exhaustion) and exercise performance during prolonged exercise (>2 h). More recently, studies have also shown ergogenic effects of CHO feeding during shorter exercise of high intensity ( approximately 1 h at >75% of maximum oxygen consumption). During prolonged exercise the mechanism behind this performance improvement is likely to be related to maintenance of high rates of CHO oxidation and the prevention of hypoglycemia. Nevertheless, other mechanisms may play a role, depending on the type of exercise and the specific conditions. The mechanism for performance improvements during higher-intensity exercise is less clear, but there is some evidence that CHO can have central effects. In the past few years, studies have investigated ways to optimize CHO delivery and bioavailability. An analysis of all studies available shows that a single CHO ingested during exercise will be oxidized at rates up to about 1 g/min, even when large amounts of CHO are ingested. Combinations of CHO that use different intestinal transporters for absorption (e.g., glucose and fructose) have been shown to result in higher oxidation rates, and this seems to be a way to increase exogenous CHO oxidation rates by 20% to 50%. The search will continue for ways to further improve CHO delivery and to improve the oxidation efficiency resulting in less accumulation of CHO in the gastrointestinal tract and potentially decreasing gastrointestinal problems during prolonged exercise.
人们普遍认为，运动期间摄入碳水化合物（CHO）可以提高耐力（至疲劳时间），并改善长时间运动（>2小时）期间的运动表现。最近，研究还表明，在高强度的短时间运动（约1小时，最大耗氧量>75%）期间摄入CHO具有增强体能的作用。在长时间运动期间，这种运动表现改善背后的机制可能与维持高碳水化合物氧化率和预防低血糖有关。然而，根据运动类型和具体条件，其他机制可能也起作用。高强度运动期间运动表现改善的机制尚不清楚，但有一些证据表明CHO可能具有中枢效应。在过去几年中，研究人员研究了优化碳水化合物输送和生物利用度的方法。对所有现有研究的分析表明，即使摄入大量碳水化合物，运动期间单次摄入的碳水化合物氧化速率最高可达约1克/分钟。已证明，使用不同肠道转运蛋白进行吸收的碳水化合物组合（如葡萄糖和果糖）可导致更高的氧化速率，这似乎是将外源性碳水化合物氧化速率提高20%至50%的一种方法。人们将继续寻找进一步改善碳水化合物输送的方法，并提高氧化效率，从而减少胃肠道中碳水化合物的积累，并可能减少长时间运动期间的胃肠道问题。
