Maughan R J, Leiper J B, Shirreffs S M
University Medical School, Scotland, United Kingdom.
Br J Sports Med. 1997 Sep;31(3):175-82. doi: 10.1136/bjsm.31.3.175.
Maintenance of fluid balance is a major concern for all athletes competing in events held in hot climates. This paper reviews recent work relating to optimisation of fluid replacement after sweat loss induced by exercising in the heat. Data are taken from studies undertaken in our laboratory. Issues investigated were drink composition, volume consumed, effects of consuming food with a drink, effects of alcohol in rehydration effectiveness, voluntary intake of fluid, and considerations for women related to the menstrual cycle. The results are presented as a series of summaries of experiments, followed by a discussion of the implications. The focus of this review is urine output after ingestion of a drink; fluid excreted in urine counteracts rehydration. Also included are data on the restoration of plasma volume losses. Ingestion of large volumes of plain water will inhibit thirst and will also promote a diuretic response. If effective rehydration is to be maintained for some hours after fluid ingestion, drinks should contain moderately high levels of sodium (perhaps as much as 50-60 mmol/l) and possibly also some potassium to replace losses in the sweat. To surmount ongoing obligatory urine losses, the volume consumed should be greater than the volume of sweat lost. Palatability of drinks is important in stimulating intake and ensuring adequate volume replacement. Where opportunities allow, the electrolytes required may be ingested as solid food consumed with a drink. There are no special concerns for women related to changes in hormone levels associated with the menstrual cycle. Ingestion of carbohydrate-electrolyte drinks in the post-exercise period restores exercise capacity more effectively than plain water. The effects on performance of an uncorrected fluid deficit should persuade all athletes to attempt to remain fully hydrated at all times, and the aim should be to start each bout of exercise in a fluid replete state. This will only be achieved if a volume of fluid in excess of the sweat loss is ingested together with sufficient electrolytes.
对于所有在炎热气候下参加比赛的运动员来说，维持体液平衡是一个主要问题。本文综述了近期有关在热环境中运动导致出汗后优化补液的研究工作。数据取自我们实验室进行的研究。所调查的问题包括饮料成分、饮用量、饮料与食物一起摄入的影响、酒精对补液效果的影响、液体的自主摄入量以及与女性月经周期相关的注意事项。结果以一系列实验总结的形式呈现，随后是对其影响的讨论。本综述的重点是饮用饮料后的尿量；尿液中排出的液体会抵消补液效果。还包括血浆容量损失恢复的数据。大量饮用纯水会抑制口渴，也会促进利尿反应。如果要在摄入液体后数小时内维持有效的补液，饮料应含有适度高水平的钠（可能高达50 - 60毫摩尔/升），也可能还含有一些钾以补充汗液中的损失。为克服持续的 obligatory 尿流失，饮用量应大于出汗量。饮料的适口性对于刺激摄入和确保充足的量替代很重要。在有机会的情况下，所需的电解质可以与饮料一起作为固体食物摄入。与月经周期相关的激素水平变化对女性没有特殊影响。运动后饮用碳水化合物 - 电解质饮料比饮用纯水更能有效地恢复运动能力。未纠正的体液不足对运动表现的影响应促使所有运动员始终努力保持充分补水，目标应该是以体液充足的状态开始每一轮运动。只有摄入超过出汗量的液体并补充足够的电解质才能实现这一点。
