Convertino V A
National Aeronautics and Space Administration, Kennedy Space Center, FL 32899.
Med Sci Sports Exerc. 1991 Dec;23(12):1338-48.
Expansion of blood volume (hypervolemia) has been well documented in both cross-sectional and longitudinal studies as a consequence of endurance exercise training. Plasma volume expansion can account for nearly all of the exercise-induced hypervolemia up to 2-4 wk; after this time expansion may be distributed equally between plasma and red cell volumes. The exercise stimulus for hypervolemia has both thermal and nonthermal components that increase total circulating plasma levels of electrolytes and proteins. Although protein and fluid shifts from the extravascular to intravascular space may provide a mechanism for rapid hypervolemia immediately after exercise, evidence supports the notion that chronic hypervolemia associated with exercise training represents a net expansion of total body water and solutes. This net increase of body fluids with exercise training is associated with increased water intake and decreased urine volume output. The mechanism of reduced urine output appears to be increased renal tubular reabsorption of sodium through a more sensitive aldosterone action in man. Exercise training-induced hypervolemia appears to be universal among most animal species, although the mechanisms may be quite different. The hypervolemia may provide advantages of greater body fluid for heat dissipation and thermoregulatory stability as well as larger vascular volume and filling pressure for greater cardiac stroke volume and lower heart rates during exercise.
在横断面研究和纵向研究中，耐力运动训练导致血容量扩张（血容量过多）已有充分记录。血浆容量扩张在长达2 - 4周的时间里几乎可解释所有运动诱发的血容量过多现象；在此之后，扩张可能在血浆和红细胞容量之间平均分配。血容量过多的运动刺激既有热成分，也有非热成分，它们会增加电解质和蛋白质的总循环血浆水平。尽管运动后蛋白质和液体从血管外转移到血管内空间可能为快速血容量过多提供一种机制，但有证据支持这样的观点，即与运动训练相关的慢性血容量过多代表全身水和溶质的净扩张。运动训练导致的体液净增加与水摄入量增加和尿量输出减少有关。尿量减少的机制似乎是通过人类更敏感的醛固酮作用增加肾小管对钠的重吸收。运动训练诱发的血容量过多在大多数动物物种中似乎是普遍存在的，尽管其机制可能大不相同。血容量过多可能具有以下优势：更多的体液用于散热和体温调节稳定性，以及更大的血管容量和充盈压，以便在运动期间实现更大的心输出量和更低的心率。
