Noakes T D, Norman R J, Buck R H, Godlonton J, Stevenson K, Pittaway D
Department of Physiology, University of Cape Town Medical School, South Africa.
Med Sci Sports Exerc. 1990 Apr;22(2):165-70.
Recent studies have shown that potentially fatal hyponatremia can develop during prolonged exercise. To determine the incidence of hyponatremia in athletes competing in ultradistance events, we measured serum sodium levels in 315 of 626 (50%) runners who were treated for collapse after two 90 km ultramarathon footraces (total starters 20,335; total finishers 18,031) and in 101 of 147 (69%) finishers in a 186 km ultratriathlon. In both races the athletes drank fluids with low sodium chloride content (less than 6.8 mmol.l-1). Hyponatremia (serum sodium level less than 130 mmol.l-1) was identified in 27 of 315 (9%) collapsed runners in the 90 km races and in none of the triathletes. In response to diuretic therapy, the runner with the most severe hyponatremia (serum sodium level = 112 mmol.l-1) excreted in excess of 7.5 l dilute urine during the first 17 h of hospitalization. These data suggest that, although symptomatic hyponatremia occurs in less than 0.3% of competitors during prolonged exercise even when they ingest little sodium chloride, it is found in a significant proportion (9%) of collapsed runners. A regulated contraction of the extracellular fluid volume would explain why the majority of athletes maintain normal serum sodium levels even though they develop a significant sodium chloride deficit during prolonged exercise. Alternatively, sodium chloride losses during prolonged exercise may be substantially less than are currently believed. Physicians treating collapsed ultradistance athletes need to be aware that as many as 10% or more of such patients may be hyponatremic.
近期研究表明，长时间运动期间可能会出现有潜在致命风险的低钠血症。为了确定参加超长距离赛事的运动员中低钠血症的发生率，我们对626名参加两场90公里超级马拉松比赛（总参赛人数20335人；总完赛人数18031人）后因虚脱接受治疗的跑步运动员中的315人（50%）以及一场186公里超级铁人三项赛的147名完赛者中的101人（69%）测量了血清钠水平。在这两项赛事中，运动员饮用的都是氯化钠含量低（低于6.8 mmol·l-1）的液体。在90公里比赛中，315名虚脱的跑步运动员中有27人（9%）被诊断为低钠血症（血清钠水平低于130 mmol·l-1），而铁人三项运动员中无人出现低钠血症。针对利尿剂治疗，低钠血症最严重（血清钠水平 = 112 mmol·l-1）的跑步运动员在住院的前17小时内排出了超过7.5升的稀释尿液。这些数据表明，尽管在长时间运动期间，即使运动员摄入很少的氯化钠，有症状的低钠血症在不到0.3%的参赛者中出现，但在相当一部分（9%）虚脱的跑步运动员中被发现。细胞外液量的调节性收缩可以解释为什么大多数运动员尽管在长时间运动期间出现明显的氯化钠缺乏，但仍能维持正常的血清钠水平。或者，长时间运动期间的氯化钠损失可能比目前认为的要少得多。治疗虚脱的超长距离运动员的医生需要意识到，多达10%或更多的此类患者可能存在低钠血症。
