Knechtle Beat, Knechtle Patrizia, Rosemann Thomas
Institute of General Practice and Health Services Research, University of Zurich, Zurich, Switzerland.
Chin J Physiol. 2011 Dec 31;54(6):379-84. doi: 10.4077/CJP.2011.AMM050.
Exercise-associated hyponatremia (EAH) has mainly been investigated in runners and triathletes. In mountain bikers, EAH was studied in two multi-stage races, but not in a single stage race. The aim of this study was to investigate the prevalence of EAH in a single-stage mountain bike ultra-marathon. In the 'Swiss Bike Masters' over 120 km with a climb of ~ 5,000 m in altitude, we determined pre and post race body mass, hematocrit, plasma sodium concentration ([Na⁺]), and urinary specific gravity in 37 cyclists. Athletes recorded their fluid intake while racing. No athlete developed EAH. The cyclists drank on average (means ± SD) 0.7 ± 0.2 l/h. Fluid intake was significantly and negatively related to race time (r = -0.41, P < 0.05), but showed no association with post race plasma [Na⁺], the change in plasma [Na⁺], post race body mass, or the change in body mass. The athletes lost 1.4 kg body mass (P < 0.05), plasma [Na⁺] decreased by 0.7% (P < 0.05), plasma volume increased by 1.4% and urinary specific gravity increased by 0.4% (P < 0.05). The change in body mass was neither related to post race plasma [Na⁺] nor to the change in plasma [Na⁺]. The decrease in plasma [Na⁺] was not related to fluid intake. The change in plasma [Na⁺] was related to post race plasma [Na⁺] (r = 0.40, P < 0.01). Ad libitum fluid intake showed no case of EAH in a single-stage mountain bike ultra-marathon. In contrast to previous findings, the faster athletes drank more than the slower ones.
运动相关性低钠血症（EAH）主要在跑步者和铁人三项运动员中进行了研究。在山地自行车运动员中，EAH在两项多阶段比赛中进行了研究，但未在单阶段比赛中进行研究。本研究的目的是调查单阶段山地自行车超级马拉松中EAH的患病率。在“瑞士自行车大师赛”中，赛程超过120公里，海拔爬升约5000米，我们测定了37名自行车运动员赛前和赛后的体重、血细胞比容、血浆钠浓度（[Na⁺]）和尿比重。运动员在比赛期间记录了他们的液体摄入量。没有运动员发生EAH。自行车运动员平均（均值±标准差）每小时饮用0.7±0.2升。液体摄入量与比赛时间显著负相关（r = -0.41，P < 0.05），但与赛后血浆[Na⁺]、血浆[Na⁺]的变化、赛后体重或体重变化均无关联。运动员体重减轻了1.4千克（P < 0.05），血浆[Na⁺]下降了0.7%（P < 0.05），血浆量增加了1.4%，尿比重增加了0.4%（P < 0.05）。体重变化与赛后血浆[Na⁺]或血浆[Na⁺]的变化均无关。血浆[Na⁺]的下降与液体摄入量无关。血浆[Na⁺]的变化与赛后血浆[Na⁺]相关（r = 0.40，P < 0.01）。在单阶段山地自行车超级马拉松中，随意摄入液体未出现EAH病例。与之前的研究结果相反，速度较快的运动员比速度较慢的运动员喝得更多。
