Sharwood Karen, Collins Malcolm, Goedecke Julia, Wilson Gary, Noakes Timothy
UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town and Sports Science Institute of South Africa, South Africa.
Clin J Sport Med. 2002 Nov;12(6):391-9. doi: 10.1097/00042752-200211000-00012.
To establish relationships between body weight changes and serum sodium during and after an Ironman Triathlon, and postrace fluid status and rectal temperature, including the incidence of hyponatremia.
Descriptive research.
The 2000 South African Ironman Triathlon, in which each athlete swam 3.8 km, cycled 180 km, and ran 42.2 km.
All entrants in the race were invited to participate in the study.
Athletes were weighed at registration, immediately prerace, immediately postrace, and 12 hours later. Blood samples were drawn at registration and immediately postrace. Rectal temperatures were measured postrace.
Starting body weight was significantly related to total finishing time (r = 0.27) and to cycling (r = 0.20) and running (r = 0.28) time. Body weight decreased significantly (p < 0.0001) during the race and had not returned to prerace values 12 hours later (p < 0.0001). Percentage change in body weight was unrelated to postrace rectal temperatures and inversely related to the postrace serum sodium concentrations (r = -0.45). Postrace serum sodium concentrations fell within a normal distribution (141.8 +/- 3.1 mmol.L(-1), mean +/- SD) and were negatively correlated to overall triathlon time (r = -0.22). Three sodium values (0.6%) were below 135 mmol.L(-1). Percentage change in body weight was unrelated to time in the marathon leg.
Percentage change in body weight was linearly related to postrace serum sodium concentrations but unrelated to postrace rectal temperature or performance in the marathon. There was no evidence that in this study, more severe levels of weight loss or dehydration were related to either higher body temperatures or impaired performance.
建立铁人三项赛期间及赛后体重变化与血清钠之间的关系，以及赛后体液状态和直肠温度之间的关系，包括低钠血症的发生率。
描述性研究。
2000年南非铁人三项赛，每位运动员需游泳3.8公里、骑自行车180公里、跑步42.2公里。
比赛的所有参赛者均受邀参与本研究。
在报名时、赛前即刻、赛后即刻以及12小时后对运动员进行称重。在报名时和赛后即刻采集血样。赛后测量直肠温度。
起始体重与总完赛时间（r = 0.27）、骑行时间（r = 0.20）和跑步时间（r = 0.28）显著相关。比赛期间体重显著下降（p < 0.0001），12小时后仍未恢复到赛前水平（p < 0.0001）。体重变化百分比与赛后直肠温度无关，与赛后血清钠浓度呈负相关（r = -0.45）。赛后血清钠浓度呈正态分布（141.8 +/- 3.1 mmol.L(-1)，均值 +/- 标准差），与铁人三项总时间呈负相关（r = -0.22）。有三个钠值（0.6%）低于135 mmol.L(-1)。体重变化百分比与马拉松赛段用时无关。
体重变化百分比与赛后血清钠浓度呈线性相关，但与赛后直肠温度或马拉松比赛表现无关。在本研究中，没有证据表明更严重的体重减轻或脱水与更高的体温或表现受损有关。
