Mudambo K S, Leese G P, Rennie M J
Department of Anatomy and Physiology, University of Dundee, UK.
Eur J Appl Physiol Occup Physiol. 1997;76(6):517-24. doi: 10.1007/s004210050284.
The aim of this study was to examine whether ingesting water alone, or dextrose (7.5 g x 100 ml(-1)) with electrolytes, or fructose/corn solids (7.5 g x 100 ml(-1)) (400 ml every 20 min) would reduce the perceived exertion associated with 16 km (3 h) walking/running in the heat compared with that perceived during exercise with no fluid intake. Perceived exertion was assessed at 1-h intervals during exercise. Blood samples, required for analysis of blood glucose, plasma sodium, plasma osmolality and plasma volume, were obtained prior to exercise and at 1-h intervals during the exercise; further samples were obtained 1-h intervals for 3 h following the exercise. Drinking fluids at regular intervals reduced the level of perceived exertion. In the test during which no fluid was ingested, body mass decreased by 4.9 (0.4) kg [mean (SEM)], but decreased less with ingestion of either the dextrose/electrolytes or fructose/corn solids solutions, or water alone [1.3 (0.2) kg, 1.6 (0.3) kg and 2.0 (0.1) kg, respectively]. Plasma volume fell by 17% when taking no fluid, but fell less when ingesting fluids. Blood glucose fell significantly (P < 0.01) when taking no fluid and rose to 8.4 (1.3) mmol x l(-1) (P < 0.001) and 6.8 (1.1) mmol x l(-1) (P < 0.01) with ingestion of the dextrose/electrolytes or fructose/corn solids solutions, respectively. Urine output was greater with ingestion of water than with any of the other drinks. Six subjects experienced fatigue during exercise with no fluid and failed to complete the exercise. These results suggest that fatigue was caused by several interacting factors: a fall in blood glucose and plasma volume, dehydration, and neuroglycopenia. Taking fluids during exercise reduced the strain and the rating of perceived exertion; this was better achieved by ingesting a dextrose/electrolytes solution.
本研究的目的是检验，与不摄入液体进行运动时相比，单独饮水、摄入含电解质的葡萄糖（7.5 g×100 ml⁻¹）或果糖/玉米固体（7.5 g×100 ml⁻¹）（每20分钟400 ml）是否能减轻在炎热环境中进行16公里（3小时）步行/跑步时的主观用力感觉。在运动期间每隔1小时评估一次主观用力感觉。在运动前以及运动期间每隔1小时采集血样，用于分析血糖、血浆钠、血浆渗透压和血浆容量；运动后3小时内每隔1小时采集更多血样。定期饮用液体可降低主观用力感觉水平。在不摄入液体的测试中，体重下降了4.9（0.4）kg[平均值（标准误）]，但摄入葡萄糖/电解质溶液、果糖/玉米固体溶液或单独饮水时体重下降较少[分别为1.3（0.2）kg、1.6（0.3）kg和2.0（0.1）kg]。不摄入液体时血浆容量下降了17%，但摄入液体时下降较少。不摄入液体时血糖显著下降（P<0.01），摄入葡萄糖/电解质溶液和果糖/玉米固体溶液时血糖分别升至8.4（1.3）mmol·l⁻¹（P<0.001）和6.8（1.1）mmol·l⁻¹（P<0.01）。饮水时的尿量比饮用其他任何饮料时都多。6名受试者在不摄入液体的运动过程中出现疲劳，未能完成运动。这些结果表明，疲劳是由多种相互作用的因素引起的：血糖和血浆容量下降、脱水以及神经低血糖症。运动期间摄入液体可减轻压力和主观用力感觉评分；摄入葡萄糖/电解质溶液能更好地实现这一点。
