Wells C L, Stern J R, Kohrt W M, Campbell K D
Med Sci Sports Exerc. 1987 Apr;19(2):137-42.
Seven men and five women triathletes ran 10 km and bicycled 40 km at race pace for the purpose of studying changes in plasma, blood, and red blood cell volumes. A second trial followed 1 wk later with the order of exercise counterbalanced (running first-cycling second; cycling first-running second). Water consumption was measured by providing water bottles on the bike phase, at 3.2 and 6.7 km on the run phase, and at the transition area. Body weight was obtained at the start and end of each phase. A 10-ml blood sample was obtained just before starting and immediately upon finishing each phase. Changes in plasma volume, blood volume, and red cell volume were calculated from hematocrit and hemoglobin values. Changes in blood volume, plasma volume, and red cell volume did not differ between the sexes; therefore, results were combined. Sequential cycling and running caused significant hemoconcentration (-6 to -8% blood volume; -8 to -10% plasma volume) with moderate dehydration (-3 to -4% body weight) despite ad libitum fluid replacement. More severe fluid compartment shifts occurred on the initial phase regardless of exercise mode. Blood volume and plasma volume changes during the second mode of exercise were minor in extent with the major differences occurring in red cell volume. When fluid changes were calculated on a per hour basis, shifts were greater during running than during cycling.
为了研究血浆、血液和红细胞体积的变化，7名男性和5名女性铁人三项运动员以比赛速度跑了10公里，并骑行了40公里。1周后进行了第二次试验，运动顺序进行了平衡处理（先跑步后骑车；先骑车后跑步）。通过在骑行阶段提供水瓶、在跑步阶段3.2公里和6.7公里处以及在转换区域提供水瓶来测量水的摄入量。在每个阶段开始和结束时测量体重。在每个阶段开始前和结束后立即采集10毫升血样。根据血细胞比容和血红蛋白值计算血浆体积、血液体积和红细胞体积的变化。血液体积、血浆体积和红细胞体积的变化在性别之间没有差异；因此，将结果合并。尽管可以随意补充液体，但连续的骑行和跑步仍导致显著的血液浓缩（血液体积减少6%至8%；血浆体积减少8%至10%）以及中度脱水（体重减少3%至4%）。无论运动模式如何，在初始阶段都会出现更严重的体液分布变化。在第二种运动模式期间，血液体积和血浆体积的变化程度较小，主要差异出现在红细胞体积上。当按每小时计算液体变化时，跑步期间的变化比骑行期间更大。
