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Medicine & Science in Sports & Exercise: October 1989
APPLIED SCIENCES: The Ultraendurance Triathlete: Physiologic and Medical Considerations: PDF Only


HILLER, W. D. B. Dehydration and hyponatremia during triathlons. Med. Sci. Sports Exerc., Vol. 21, No. 5 (Supplement), pp. S219–S221, 1989. In ultraendurance triathlons, dehydration and electrolyte balance are important factors in race completion and level of performance. Dehydration is the most common reason for a triathlete in the Hawaii Ironman Triathlon to need medical assistance. Hyponatremia is the predominant electrolyte disturbance. We have previously described exercise-induced hyponatremia and documented its incidence as a function of race length and state of hydration. This syndrome, dehydration plus hyponatremia, is extremely rare in races lasting less than 4 h but becomes common in races lasting longer than 8 h. Recommendations are made to help ultraendurance athletes understand and maintain proper fluid and electrolyte balance.

©1989The American College of Sports Medicine