Medicine & Science in Sports & Exercise
ORIGINAL INVESTIGATIONS: PDF Only
a possible complication during endurance exercise
NOAKES, TIMOTHY D.; GOODWIN, NEIL; RAYNER, BRIAN L.; BRANKEN, TREVOR; TAYLOR, ROBERT K. N.
The Metropolitan Sport Science Centre, Department of Physiology, University of Cape Town, Medical School, Cape Town, SOUTH AFRICA; and
Addington Hospital and the Departments of Medicine and Anaesthesia, University of Natal Medical School, Durban, SOUTH AFRICA
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Abstract
Four athletes developed water intoxication (hyponatremia) during endurance events lasting more than 7 h. The etiology of the condition appears to be voluntary hyperhydration with hypotonic solutions combined with moderate sweat sodium chloride losses. The reason why the fluid excess in these runners was not corrected by increased urinary losses is unknown. When advised to drink less during prolonged exercise, three of the athletes have subsequently completed prolonged endurance events uneventfully.