Daries H N, Noakes T D, Dennis S C
University of Cape Town Bioenergetics of Exercise Research Unit, Sports Science Institute of South Africa, Newlands.
Med Sci Sports Exerc. 2000 Oct;32(10):1783-9. doi: 10.1097/00005768-200010000-00019.
In this study, we examined the effects of greater than ad libitum rates of fluid intake on 2-h running performances.
Eight male distance runners performed three runs on a treadmill at 65% of peak oxygen uptake (VO2peak) for 90 min and then ran "as far as possible" in 30 min in an air temperature of 25 degrees C, a relative humidity of 55% and a wind speed of 13-15 km x h(-1). During the runs, the subjects drank a 6.9% carbohydrate (CHO)-electrolyte solution either ad libitum or in set volumes of 150 or 350 mL x 70 kg(-1) body mass (approximately 130 or 300 mL) every 15-20 min.
Higher (approximately 0.9 vs 0.4 L x h(-1)) rates of fluid intake in the 350 mL x 70 kg(-1) trial than in the other trials had minimal effects on the subjects' urine production (approximately 0.1 L x h(-1)), sweat rates (approximately 1.2 L x h(-1)), declines in plasma volume (approximately 8%), and rises in serum osmolality (approximately 5 mosmol x L(-1)) and Na+ concentrations (approximately 7 mEq x L(-1)). A greater (approximately 1.0 vs 0.5 g x min(-1)) rate of CHO ingestion in the 350 mL x 70 kg(-1) trial than in the other trials also did not affect plasma concentrations of glucose (> or = 5 mmol x L(-1)) and lactate (approximately 3 mmol x L(-1)) during the performance runs. In all three performance runs, increases in running speeds from approximately 14 to 15-16 km x h(-1) and rises in exercise intensities from approximately 65% to 75% of VO2peak elevated plasma lactate concentrations from approximately 1.5 to 3 mmol x L(-1) and accelerated CHO oxidation from approximately 13 to 15 mmol x min(-1). The only effect of the additional intake of approximately 1.0 L of fluid in the 350 mL x 70 kg(-1) trial was to produce such severe gastrointestinal discomfort that two of the eight subjects failed to complete their performance runs.
Greater rates of fluid ingestion had no measurable effects on plasma volume and osmolality and did not improve 2-h running performances in a 25 degrees C environment.
在本研究中，我们考察了高于随意饮水速率的液体摄入量对2小时跑步成绩的影响。
八名男性长跑运动员在跑步机上以峰值摄氧量（VO2peak）的65%进行三次90分钟的跑步，然后在25摄氏度、相对湿度55%、风速13 - 15千米/小时的环境中，在30分钟内“尽可能远地”跑步。在跑步过程中，受试者随意饮用或每隔15 - 20分钟按150或350毫升/70千克体重（约130或300毫升）的固定量饮用6.9%的碳水化合物（CHO）电解质溶液。
与其他试验相比，在350毫升/70千克体重的试验中较高的（约0.9对0.4升/小时）液体摄入速率对受试者的尿量（约0.1升/小时）、出汗率（约1.2升/小时）、血浆量下降（约8%）以及血清渗透压升高（约5毫摩尔/升）和钠离子浓度升高（约7毫当量/升）影响极小。与其他试验相比，在350毫升/70千克体重的试验中较高的（约1.0对0.5克/分钟）CHO摄入速率在跑步过程中也未影响血浆葡萄糖（≥5毫摩尔/升）和乳酸（约3毫摩尔/升）浓度。在所有三次跑步试验中，跑步速度从约14千米/小时提高到15 - 16千米/小时，运动强度从约VO2peak的65%提高到75%，使血浆乳酸浓度从约1.5毫摩尔/升升高到3毫摩尔/升，并使CHO氧化从约13毫摩尔/分钟加速到15毫摩尔/分钟。在350毫升/70千克体重的试验中额外摄入约1.0升液体的唯一影响是导致严重的胃肠道不适，八名受试者中有两名未能完成跑步试验。
在25摄氏度环境中，较高的液体摄入速率对血浆量和渗透压没有可测量的影响，也未改善2小时跑步成绩。
