Myhre L G, Hartung G H, Tucker D M
Eur J Appl Physiol Occup Physiol. 1982;48(2):227-40. doi: 10.1007/BF00422984.
Plasma volume (PV), blood-borne substrate, and electrolyte responses to a warm weather (WBGT 15.5-24.5 degrees C) marathon race were observed in four male and two female runners averaging 48 years of age. Additionally, continuous recordings were made of heart rate (HR) in three, and of rectal temperature (Tre) in two of the men. The race was finished by three of the men, with an average time of 3.61 h, a running pace estimated to require from 60-66% of the runner's VO2 max. Near steady state levels for HR and Tre, ranging from 140-165 beats . min-1 and from 38.5-39.3 degrees C, respectively, were reached early in the race. Total and percentage weight losses for the finishers were 2.52 kg and 3.9%, 2.18 kg and 3.4%, 4.77 kg and 6.7%, respectively; corresponding reductions in PV for these runners were 5.4%, 13.2%, and 27.4%. Pre-race control and immediate post-race serum glucose concentrations averaged 109 and 154 mg . dl-1 respectively. Final blood lactate values ranged from 11-42 mg . dl-1. Thus, it may be concluded that middle-aged runners who were successful in completing the marathon in a warm environment did so while maintaining steady state levels of HR and Tre. Although only water was ingested during the race, serum glucose for the finishing runners remained above, while serum [Na+] and [Cl-] remained within +/- 8% of, control values throughout the run. Complete data obtained from only one of the runners suggest that the initial exercise-induced reduction in PV is not augmented by subsequent cumulative dehydration provided water intake during the race is sufficient to limit weight loss to less than 4%.
观察了4名男性和2名女性跑步者（平均年龄48岁）在温暖天气（湿球黑球温度15.5 - 24.5摄氏度）下马拉松比赛中血浆容量（PV）、血源性底物和电解质的反应。另外，对3名男性进行了心率（HR）的连续记录，对其中2名男性进行了直肠温度（Tre）的连续记录。3名男性完成了比赛，平均用时3.61小时，跑步速度估计需要达到跑步者最大摄氧量的60 - 66%。在比赛早期，HR和Tre达到了接近稳态水平，分别为140 - 165次·分钟⁻¹和38.5 - 39.3摄氏度。完赛者的总体重减轻和体重减轻百分比分别为2.52千克和3.9%、2.18千克和3.4%、4.77千克和6.7%；这些跑步者的PV相应减少了5.4%、13.2%和27.4%。赛前对照和赛后即刻血清葡萄糖浓度平均分别为109和154毫克·分升⁻¹。最终血乳酸值范围为11 - 42毫克·分升⁻¹。因此，可以得出结论，在温暖环境中成功完成马拉松比赛的中年跑步者是在维持HR和Tre稳态水平的情况下做到的。尽管比赛期间只摄入了水，但完赛跑步者的血清葡萄糖在整个跑步过程中保持在对照值以上，而血清[Na⁺]和[Cl⁻]保持在对照值的±8%范围内。仅从一名跑步者获得的完整数据表明，如果比赛期间的水分摄入足以将体重减轻限制在4%以下，那么最初运动引起的PV减少不会因随后的累积脱水而加剧。
