Barr S I, Costill D L, Fink W J
Human Performance Laboratory, Ball State University, Muncie, IN 47306.
Med Sci Sports Exerc. 1991 Jul;23(7):811-7.
This study assessed the need to replace sodium in endurance exercise less than or equal to 6 h in duration by comparing responses to fluid replacement with water, saline (25 mmol.l-1), or no fluid. Eight subjects (five male, three female) participated in three 6-h exercise trials on an electrically braked cycle ergometer at 55% VO2max, at 30 degrees C and 50% r.h. In the water (W) and saline (S) trials, sufficient fluid was ingested to balance sweat and urinary fluid losses, while in the third trial, no fluid (NF) was ingested. Plasma sodium less than or equal to 130 mmol.l-1 was a criterion for trial termination. In the NF trial, heart rate, rectal temperature, plasma sodium, plasma aldosterone, and rating of perceived exertion were all significantly higher (P less than 0.001) than during W and S, whereas plasma volume was lower (P less than 0.001). On average, subjects terminated this trial 1.5 h prior to its scheduled completion, having lost 6.4% body weight. In contrast, no significant differences between fluid replacement with W or S were detected, although the effect of time on all aforementioned variables was highly significant (P less than 0.001). Saline intake was not associated with significantly higher plasma sodium during exercise than was water intake: plasma sodium decreased significantly during both W (to 135.5 +/- 0.5 mmol.l-1) and S (to 137.3 +/- 0.7 mmol.l-1). No subject had to terminate a trial based on plasma sodium less than or equal to 130 mmol.l-1.(ABSTRACT TRUNCATED AT 250 WORDS)
本研究通过比较水、生理盐水（25 mmol·l-1）或无补液情况下的补液反应，评估了在持续时间小于或等于6小时的耐力运动中补充钠的必要性。八名受试者（五名男性，三名女性）在电动刹车的自行车测力计上，于55%最大摄氧量、30摄氏度和50%相对湿度条件下进行了三次6小时的运动试验。在水（W）和生理盐水（S）试验中，摄入足够的液体以平衡汗液和尿液的液体流失，而在第三次试验中，不摄入液体（NF）。血浆钠小于或等于130 mmol·l-1是试验终止的标准。在NF试验中，心率、直肠温度、血浆钠、血浆醛固酮和主观用力程度均显著高于W和S试验期间（P<0.001），而血浆量较低（P<0.001）。平均而言，受试者在预定完成时间前1.5小时终止了该试验，体重减轻了6.4%。相比之下，未检测到W或S补液之间的显著差异，尽管时间对所有上述变量的影响非常显著（P<0.001）。运动期间，摄入生理盐水与摄入水相比，血浆钠升高并不显著：W试验（降至135.5±0.5 mmol·l-1）和S试验（降至137.3±0.7 mmol·l-1）期间血浆钠均显著下降。没有受试者因血浆钠小于或等于130 mmol·l-1而不得不终止试验。（摘要截断于250字）
