Exercise-Associated Hyponatremia, Hypernatremia, and Hydration Status in Multistage Ultramarathons

The incidence of EAH in multistage ultramarathons was similar to marathons and single-stage ultramarathons, but the cumulative incidence of hypernatremia was 3 times greater than that of EAH. EAH was associated with increased weight gain (overhydration) in early stage nonfinishers and postrace finishers.