Hydration Strategies of Runners in the London Marathon
Williams J, Tzortziou-Brown V, Malliaras P, Perry M, and Kipps C. Clin J Sport Med. 2012 [Epub Ahead of Print].
Exercise-associated hyponatremia (EAH) is a condition which occurs during or after prolonged endurance exercise, and is defined as a serum sodium concentration of less than 135mmol/L. EAH is commonly caused by excess fluid intake during activity and may result in altered mental status and in some cases death. Therefore, Williams and colleagues utilized a questionnaire to assess runners’ hydration plans for before, during, and after the London Marathon, and evaluated how closely these plans followed the current recommendations. Of 232 invited participants, 217 (66 women, 151 men) completed the questionnaire. Of the respondents, 208 (96%) had a “plan regarding prerace fluid intake during the race”. Analysis revealed that 45 (22%) participants planned to drink from all 24 water stations, potentially a total consumption of 7.9 liters of fluids. The median total volume participants planned to drink was approximately 1.2 liters. One hundred and ninety one (88%) participants reported a fluid-intake plan for 6 hours post-race. Again, the participants planned to consume a median total volume of 1.2 liters of fluids. When asked about the source of information, 93% of participants stated that their information was gained on race day through the London Marathon magazine or friends with running experience. Other factors that influenced runners’ drinking strategies were temperature (33%) and thirst (25%). The questionnaire further revealed that 141 (65%) participants “heard of hyponatremia” while only 77 (37%) proved to have a “basic understanding of hyponatremia”. The analysis demonstrated a severe lack of understanding regarding appropriate fluid intake guidelines. While sources (EAH Consensus Development Conference statement, International Marathon Medical Directors Association) recommend that runners should “drink to thirst,” only 25% (54) of respondents reported thirst was a factor in determining fluid intake. Despite the relatively low understanding of fluid intake guidelines, 151 (70%) stated in the questionnaire that they read the official race magazine, provided to all participants of the London Marathon, which included appropriate fluid intake recommendations.
Clearly, there is a gap in understanding between provided information on fluid intake and actual practices. This study demonstrates that more needs to be done to educate runners on appropriate fluid intake plans before, during, and after races. The authors highlighted that the official race magazine would be an excellent source of information. While this publication already has guidelines for proper appropriate fluid intake, the author states the information was “located near to the back of the magazine, the official medical advice was less prominent than advertising features about sports drinks in the early section which, of note, make no mention of hyponatremia or the potential dangers of excessive drinking.” While EAH and its causes are well understood the information has not yet reached our athletes. In conclusion the authors call for changing the drinking behavior of runners through more effective education. What do you think? Have you had, or know someone who has, struggled with EAH? What are some strategies that you think would be most effective in informing this population?
Written by: Kyle Harris
Reviewed by: Jeffrey Driban
Williams J, Tzortzioubrown V, Malliaras P, Perry M, & Kipps C (2012). Hydration Strategies of Runners in the London Marathon. Clinical Journal of Sport Medicine PMID: 22246343