Human Performance Laboratory, Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX 78712, USA.
Med Sci Sports Exerc. 2010 Sep;42(9):1669-74. doi: 10.1249/MSS.0b013e3181d6c72a.
This study determined if changes in serum sodium concentration are related to fluid balance as well as sweat sodium losses in triathletes competing in the Hawaii Ironman triathlon.
Endurance trained athletes (N = 46, age = 24-67 yr) were studied during 30 min of stationary cycling at 70%-75% of HRmax in a warm outdoor laboratory (26.4 degrees C +/- 1.7 degrees C wet bulb globe temperature [WBGT], 28.3 degrees C +/- 1.2 degrees C dry bulb [DB]) 3-7 d before race day. Sweat sodium concentration was measured from absorbent patches on the forearm and scapula, and sweating rate was derived from changes in body mass. Before and after the race, serum sodium concentration, body mass, and nutritional intake during the race were also measured (N = 46). Sweating and race day comparisons and changes in serum sodium concentration were analyzed via Student's t-test, correlation, and multiple regression.
In men, the change in serum sodium concentration during the race was correlated with relative sweating rate (mL.kg.h; r = -0.49, P = 0.012), rate of sweat sodium loss (mEq.kg.h; r = -0.44, P = 0.023), and body mass change (kg; r = -0.54, P = 0.005). Together, the rate of sweat sodium loss and body mass change accounted for 46% of the change in serum sodium concentration in men (R = 0.46). In women, body mass change alone was significantly correlated with the change in serum sodium concentration (r = 0.31). The rate of sodium intake (mEq.kg.h) was related to the rate of sweat sodium loss in women (mEq.kg.h; r = 0.64, P = 0.035) but not in men (r = 0.27, P = 0.486).
Changes in serum sodium concentration during an ultraendurance triathlon are significantly related to interactions of fluid balance, sweat sodium loss, and sodium ingestion.
本研究旨在确定血清钠浓度的变化是否与铁人三项运动员在夏威夷铁人三项赛中进行的流体平衡以及汗液钠流失有关。
在比赛日前 3-7 天，46 名耐力训练运动员（年龄 24-67 岁）在温暖的户外实验室（26.4°C±1.7°C湿球球温度[WBGT]，28.3°C±1.2°C干球[DB]）中以 70%-75%的最大心率进行 30 分钟的固定自行车运动。前臂和肩胛骨上的吸收垫测量汗液中的钠浓度，通过体重变化得出出汗率。比赛前后，还测量了血清钠浓度、体重和比赛期间的营养摄入（N=46）。通过学生 t 检验、相关性和多元回归分析比较和分析比赛期间血清钠浓度的变化。
在男性中，比赛期间血清钠浓度的变化与相对出汗率（mL.kg.h；r=-0.49，P=0.012）、汗液钠流失率（mEq.kg.h；r=-0.44，P=0.023）和体重变化（kg；r=-0.54，P=0.005）相关。汗液钠流失率和体重变化共占男性血清钠浓度变化的 46%（R=0.46）。在女性中，体重变化单独与血清钠浓度的变化显著相关（r=0.31）。钠摄入量（mEq.kg.h）与女性的汗液钠流失率（mEq.kg.h；r=0.64，P=0.035）相关，但与男性无关（r=0.27，P=0.486）。
在超长耐力铁人三项赛中，血清钠浓度的变化与液体平衡、汗液钠流失和钠摄入的相互作用密切相关。
