Fluid and electrolyte status in athletes receiving medical care at an ultradistance triathlon.

Thirty competitors in the Hawaii Ironman Triathlon were prospectively studied to determine whether fluid and electrolyte disturbances were causes for seeking race-day medical care. Athlete weights were significantly (p < 0.0001) decreased during the race, but decreases were not different in treated (n = 11; % delta wt -2.3 +/- 2.9) versus not treated (n = 19; % delta wt - 2.0 +/- 1.9) athletes. Hyponatremia occurred in nine athletes (30%), and hypomagnesemia in six (20%), but only half of athletes were either electrolyte imbalance sought care. Although athletes receiving medical care may have fluid and electrolyte problems, these abnormalities may also occur in healthy athletes.