Date of Award

9-14-2009

Degree Type

Closed Thesis

Degree Name

Master of Science (MS)

Department

Nutrition

First Advisor

Dan Benardot - Chair

Abstract

Purpose: To examine hydration practices and risk factors, including the over-consumption of fluids as measured by weight gain, associated with hyponatremia in non-elite runners participating in a cold weather half-marathon and marathon, and to observe gender-related differences in pre- to post-race weight change. Methods: Using an IRB-approved protocol, pre-race weight was measured and participants completed a pre-race questionnaire that included questions on age, gender, non-steroidal anti-inflammatory drug (NSAID) use, hydration beverage preferences, and race experience. Weight was also measured on participating racers shortly after they crossed the finish line, where a post-race questionnaire was also completed. Post-race questions related to during-race behaviors, including during-race fluid consumption frequency, fluid types consumed, number of urination stops, NSAID use just prior to race, and time to complete the race. Results: Pre- and post-race weights were measured for 17 marathon and 75 half-marathon participants. Marathon: The mean weight change for marathon participants was non-significant (-0.56 kg + 1.25; p=0.08). There was a statistically significant difference (p=0.012) in weight change between those who took NSAIDs prior to the race (+0.9 kg ± 1.4) and those who did not (-0.86 kg ± 1.0). Half-marathon: The mean weight change for half-marathon participants was non-significant (+0.14 kg + 1.2; p=0.33). There was a significantly different (p < .01) weight change between males (-0.57 kg ± 0.94) and females (+0.73 kg ± 1.1). There was no statistically significant difference in weight change between those who took NSAIDs and those who did not. Fluid consumption frequency was positively correlated with weight change (R=0.335; p=0.006) in half-marathon participants and (R=0.407; p=0.015) in female half-marathon participants, and finishing time was positively correlated with weight change (R=0.356, p=0.003). Conclusions: On average, the race-related weight change in the marathon runners was negative and not statistically significant, and the race-related weight change in the half-marathoners was positive and not statistically significant. Marathoners who used NSAIDs before the race gained significantly more weight than those who did not. Fluid consumption frequency in the half-marathoners was positively correlated with weight change, and finishing time in half-marathoners was positively correlated with weight change. On average, there was a significant difference (p<.01) in weight gain/loss pattern in males and females, with male half-marathoners losing weight and female half-marathoners gaining weight. These data suggest that females, slower runners, and those using NSAIDs prior to a cold weather endurance event may be at higher risk for over-hydration (as measured by weight gain), which is a major risk factor in hyponatremia.

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