UC San Diego

OBJECTIVE: To study hydration plans and understanding of exercise-associated hyponatremia (EAH) among current marathon runners. DESIGN: Cross-sectional study. SETTING: Southern California 2018 summer marathon. PARTICIPANTS: Two hundred ten marathon runners. INTERVENTIONS: Survey administered 1 to 2 days before the race. Race times were obtained from public race website. MAIN OUTCOME MEASURES: Planned frequency of hydration; awareness of, understanding of, and preventative strategies for dehydration and EAH; resources used to create hydration plans; drink preferences. RESULTS: When the participants were split into 3 equal groups by racing speed, the slower tertile intended to drink at every mile/station (60%), whereas the faster tertile preferred to drink every other mile or less often (60%), although not statistically significant. Most runners (84%) claimed awareness of EAH, but only 32% could list a symptom of the condition. Both experienced marathoners and the faster tertile significantly had greater understanding of hyponatremia compared with first-time marathoners and the slower tertile, respectively. Less than 5% of marathoners offered drink to thirst as a prevention strategy for dehydration or EAH. CONCLUSION: Slower runners plan to drink larger volumes compared with their faster counterparts. Both slower and first-time marathoners significantly lacked understanding of EAH. These groups have plans and knowledge that may put them at higher risk for developing EAH. Most marathon runners did not know of the guidelines to drink to thirst, suggesting the 2015 EAH Consensus statement may not have had the desired impact.