Lyons T P, Riedesel M L, Meuli L E, Chick T W
Department of Biology, University of New Mexico, Albuquerque 87131.
Med Sci Sports Exerc. 1990 Aug;22(4):477-83.
Hypohydration reduces exercise performance and thermoregulatory capacity in the heat. Hyperhydration prior to exercise may decrease, delay, or eliminate the detrimental effects of hypohydration. The rapid clearance of excess fluid makes hyperhydration of subjects with common beverages difficult. Glycerol, a natural metabolite which is rapidly absorbed, has osmotic action, and is evenly distributed within the body fluid compartments, was tested as a possible hyperhydrating agent. In six subjects, the following fluid regimens at time 0 were randomly administered on three separate days: in trial 1, glycerol (1 g.kg-1 body weight) plus water (21.4 ml.kg-1 body weight); in trial 2, water (21.4 ml.kg-1); and in trial 3, water (3.3 ml.kg-1) was ingested at time 0. The subjects performed moderate exercise (equivalent to 60% VO2max in a comfortable environment) in a hot dry environment. The exercise started at 2.5 h after the fluids were ingested. The urine volume prior to exercise was decreased when glycerol was ingested, thus resulting in glycerol-induced hyperhydration. During the exercise following the glycerol-induced hyperhydration, there was elevated sweat rate and lower rectal temperature during the moderate exercise in the heat. There were no changes in hemoglobin, hematocrit, or serum electrolyte concentrations following glycerol intake. These data support the hypothesis that glycerol-induced hyperhydration reduces the thermal burden of moderate exercise in the heat.
低水合状态会降低在高温环境下的运动表现和体温调节能力。运动前进行高水合处理可能会减轻、延缓或消除低水合状态的有害影响。普通饮料难以使受试者快速清除多余液体来实现高水合状态。甘油是一种天然代谢产物，吸收迅速，具有渗透作用，且能均匀分布于体液各部分，被作为一种可能的高水合剂进行了测试。在六名受试者中，在三个不同日期的0时刻随机给予以下液体方案：试验1中，甘油（1克/千克体重）加水（21.4毫升/千克体重）；试验2中，水（21.4毫升/千克体重）；试验3中，在0时刻摄入水（3.3毫升/千克体重）。受试者在炎热干燥的环境中进行中等强度运动（相当于在舒适环境中60%的最大摄氧量）。运动在摄入液体2.5小时后开始。摄入甘油后运动前的尿量减少，从而导致甘油诱导的高水合状态。在甘油诱导的高水合状态后的运动过程中，在炎热环境下进行中等强度运动时出汗率升高，直肠温度降低。摄入甘油后血红蛋白、血细胞比容或血清电解质浓度没有变化。这些数据支持了甘油诱导的高水合状态可减轻在炎热环境下中等强度运动的热负荷这一假设。
