Exercise-Associated Hyponatremia in the Tropics

Abstract

I was interested to read the recent article of Lee and associates [6] suggesting that exercise-associated hyponatremia (EAH) could cause problems for the long-distance athlete, even if races were conducted in an environment as warm as Singapore. Their findings related to 42 and 84 km events, both of which were run under relatively unfavorable conditions (an average dry-bulb temperature of 29 ℃, with a relative humidity of 89% and a wind-speed of only 0.3 m/s). One of 4 659 completing marathoners and 7 of the 407 completing ultramarathoners reported to the medical tent with symptoms; the marathoner and 2 of the ultramarathoners had blood sodium levels <135 mE/L, and were thus diagnosed as cases of EAH. On the basis of this information, the authors reported (p. 299) “The incidence of EAH in the 84-km run (33.2 per 10 000) is>18-fold higher than the incidence of EAH in the 42-km runners (1.8 per 10 000).”.