Author and graduation date: Kari D. ABBOTT, September, 2002

Committee members: Jeanne Nichols-Bernhard (Chair), Michael J. Buono, Colleen Kelly

Thesis title: Hyponatremia and Adventure Racing

This case-controlled study is the first documented report of hyponatremia and adventure racing. Six male and five female trained athletes competing in the October 2001 Walkabout Adventure Races were studied. The purpose of the study was to determine hydration status and serum sodium levels of the Adventure Racers both pre- and post-race. All subjects completed questionnaires before and after the race regarding fluid and sodium preparation. Additionally and post-race symptoms of hyponatremia were determined. Objective data collection included pre- and post-race measures of body weight and serum sodium levels. Food and fluid intake was also tracked and documented for each subject to determine total and hourly intakes. Environmental conditions throughout the race were also documented. Although none of the subjects were able to complete the race, analysis of the data revealed mean body weight loss among the subjects to be 1.53 kg + 1.20, equivalent to 1.98% of pre-race body weight. Mean post-race serum sodium was 134.67 mEq/L + 7.33; six of the 11 subjects had post-race serum sodium levels within the classification of hyponatremia (<135 mEq/L). Mean hourly fluid and sodium intake levels were 309 ml + 100 and 295 mg + 126, respectively. Environmental conditions during the race were relatively mild with a high of 34 degrees Celsius and a low of 9 degrees Celsius, corresponding humidity measurements were 43% and 70%, respectively. Although the subjects consumed less fluid than recommended by the American College of Sports Medicine, over half of the 11 subjects developed mild hyponatremia. Further research is needed to determine whether the current recommended fluid and electrolyte intakes are appropriate for ultraendurance events similar to the Adventure Race.

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