Exercise-Associated Hyponatremia, Hypernatremia, and Hydration Status in Multistage Ultramarathons
Brian J Krabak1, Grant S Lipman2, Brandee L Waite3
1Department of Rehabilitation, Orthopedics and Sports Medicine, University of Washington and Seattle Children's Sports Medicine, Seattle, WA (Dr Krabak).
Wilderness & Environmental Medicine
|August 8, 2017
Summary
Exercise-associated hyponatremia (EAH) and hypernatremia are common in multistage ultramarathons. Hypernatremia occurred three times more often than EAH, with dehydration increasing throughout the race.
Area of Science:
- Sports Medicine
- Endurance Sports Physiology
- Exercise-Associated Hyponatremia
Background:
- Dysnatremia and hydration status are critical but understudied in multistage ultramarathons.
- Understanding these conditions is vital for athlete safety and performance in extreme endurance events.
Purpose of the Study:
- To determine the incidence and prevalence of exercise-associated hyponatremia (EAH) and hypernatremia.
- To assess hydration status during a 250-km multistage ultramarathon.
Main Methods:
- Prospective observational cohort study of 128 runners in a 250-km multistage desert ultramarathon.
- Collected prerace and poststage body weight and serum sodium levels at stages 1, 3, and 5.
Main Results:
- Cumulative incidence of EAH was 14.8%, while hypernatremia was 52.3%.
- Dehydration increased progressively (S1=22.1%, S3=51.2%, S5=53.5%).
- EAH correlated with weight gain (overhydration) (r=-0.21, P=.02); early nonfinishers had higher EAH rates.
Conclusions:
- EAH incidence in multistage ultramarathons mirrors single-stage events.
- Hypernatremia cumulative incidence was threefold higher than EAH.
- EAH linked to overhydration in early nonfinishers and postrace finishers.
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