Physiology and Hydration Beliefs Affect Race Behavior but not Post-Race Sodium in 161-km Ultramarathon Finishers Journal Article

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Authors: Winger, J. M.; Hoffman, M. D.; Hew-Butler, T. D.; Stuempfle, K. J.; Dugas, J. P.; Fogard, K.; Dugas, L. R.
Article Title: Physiology and Hydration Beliefs Affect Race Behavior but not Post-Race Sodium in 161-km Ultramarathon Finishers
Abstract: PURPOSE: To determine if beliefs about physiology and rehydration affect ultramarathon runners' hydration behaviors, or if these beliefs increase the risk for exercise-associated hyponatremia (EAH). METHODS: Participants of the 2011 161-km Western States Endurance Run completed a pre-race questionnaire, pre-race and post-race body mass measurements, and post-race assessment of serum sodium ([Na+]). RESULTS: Of 310 finishers, 309 (99.7%) completed the pre-race questionnaire and 207 (67%) underwent post-race blood studies. Twelve (5.8%) finishers had asymptomatic EAH ([Na+] range 131-134 mmol/L). The most common hydration plan (43.1%) was drinking according to schedule, and these runners did so in order to replace fluid lost when sweating (100%) and to avoid dehydration (81.2%). Pre-race drinking plan was not associated with post-race [Na+] or the development of post-race hyponatremia. There also were no group differences between those with and without EAH for any other variables including planned energy intake or knowledge of fluid balance. Runners not planning to drink to thirst trended towards more influence from advertisements (P=0.056) and were significantly more influenced by scientific organizations (P=0.043) than runners with other drinking plans. Finally, runners who believe that EAH is caused by excessive drinking adopted a lower volume drinking plan (P=0.005), while runners who believe that EAH is caused by sodium loss via sweating reported more common utilization of sodium supplementation during the race (P=0.017). CONCLUSIONS: Beliefs regarding the causes of EAH alter race behaviors, including drinking plan and sodium supplementation, but do not appear to affect the likelihood of developing EAH during a 161km ultramarathon.
Journal Title: International journal of sports physiology and performance
Volume: 8
Issue: 5
ISSN: 1555-0265; 1555-0265
Publisher: Unknown  
Date Published: 2013
Start Page: 536
End Page: 541
Language: ENG
Notes: ID: 13028; JID: 101276430; aheadofprint