Marathoners Lack Understanding of Exercise-Associated Hyponatremia

Participants in the London marathon have a spotty understanding of the causes and potential dangers of exercise-associated hyponatremia, researchers at the Centre for Sports and Exercise Medicine at the University of London have found.

The researchers had participants in the marathon fill out a questionnaire including questions on their plans for fluid consumption during the race as well as their sources of information regarding proper fluid consumption and their understanding of the causes and effects of hyponatremia.

The results found that 93.1 percent of those surveyed had received information about drinking fluids on the day of the marathon and that 95.8 percent had a plan regarding fluid intake. In addition, 20.7 percent planned to drink at all 24 water stations along the race route and just 25.3 percent planned to drink according to their level of thirst. Most alarmingly, 12 percent planned to drink enough water to put them at risk of exercise-associated hyponatremia. Overall, 68.0 percent of the runners had heard of the danger of hyponatremia or low sodium levels, but just 35.5 percent had a basic understanding of the condition's cause and effects.

“Marathon runners lack knowledge about appropriate fluid intake to prevent hyponatremia on race day,” the researchers conclude in the study’s abstract. “Effective educational interventions are still necessary to prevent overdrinking during marathons.”

The study was published online ahead of print on Jan. 13 in the Clinical Journal of Sport Medicine.