Kenefick R W, Maresh C M, Armstrong L E, Riebe D, Echegaray M E, Castellani J W
US Army Research Institute of Environmental Medicine, Thermal and Mountain Medicine Division, Natick, MA 01760, USA.
J Appl Physiol (1985). 2007 May;102(5):1899-905. doi: 10.1152/japplphysiol.00920.2006. Epub 2007 Feb 22.
This study examined the effects of rehydration (Rehy) with fluids of varying tonicities and routes of administration after exercise-induced hypohydration on exercise performance, fluid regulatory hormone responses, and cardiovascular and thermoregulatory strain during subsequent exercise in the heat. On four occasions, eight men performed an exercise-dehydration protocol of approximately 185 min (33 degrees C) to establish a 4% reduction in body weight. Following dehydration, 2% of the fluid lost was replaced during the first 45 min of a 100-min rest period by one of three random Rehy treatments (0.9% saline intravenous; 0.45% saline intravenous; 0.45% saline oral) or no Rehy (no fluid) treatment. Subjects then stood for 20 min at 36 degrees C and then walked at 50% maximal oxygen consumption for 90 min. Subsequent to dehydration, plasma Na(+), osmolality, aldosterone, and arginine vasopressin concentrations were elevated (P < 0.05) in each trial, accompanied by a -4% hemoconcentration. Following Rehy, there were no differences (P > 0.05) in fluid volume restored, post-rehydration (Post-Rehy) body weight, or urine volume. Percent change in plasma volume was 5% above pre-Rehy values, and plasma Na(+), osmolality, and fluid regulatory hormones were lower compared with no fluid. During exercise, skin and core temperatures, heart rate, and exercise time were not different (P > 0.05) among the Rehy treatments. Plasma osmolality, Na(+), percent change in plasma volume, and fluid regulatory hormones responded similarly among all Rehy treatments. Neither a fluid of greater tonicity nor the route of administration resulted in a more rapid or greater fluid retention, nor did it enhance heat tolerance or diminish physiological strain during subsequent exercise in the heat.
本研究考察了运动诱发低水合状态后，通过不同张力液体及给药途径进行补液（Rehy）对后续热环境运动中运动表现、液体调节激素反应以及心血管和体温调节应激的影响。八名男性在四种情况下进行了约185分钟（33摄氏度）的运动脱水方案，以使体重减轻4%。脱水后，在100分钟休息期的前45分钟内，通过三种随机补液处理之一（0.9%盐水静脉注射；0.45%盐水静脉注射；0.45%盐水口服）或不进行补液（无液体）处理，补充2%丢失的液体。然后受试者在36摄氏度站立20分钟，接着以最大耗氧量的50%步行90分钟。脱水后，各试验中血浆Na⁺、渗透压、醛固酮和精氨酸加压素浓度均升高（P<0.05），同时伴有-4%的血液浓缩。补液后，补液量恢复、补液后（Post-Rehy）体重或尿量均无差异（P>0.05）。血浆量变化百分比比补液前值高5%，与无补液相比，血浆Na⁺、渗透压和液体调节激素较低。运动期间，补液处理之间的皮肤和核心温度、心率及运动时间无差异（P>0.05）。所有补液处理中，血浆渗透压、Na⁺、血浆量变化百分比和液体调节激素反应相似。更高张力的液体或给药途径均未导致更快或更多的液体潴留，也未增强热耐受性或减轻后续热环境运动中的生理应激。
