title: Hydration strategies, weight change and performance in a 161 km ultramarathon.
abstract: To examine controversies about hydration strategies, participants (383 starters) of a 161 km ultramarathon (maximum temperature 39.0°C) underwent body weight measurements before, during and after the race; and completed a post-race questionnaire on drinking strategies and sodium supplementation use during 4 race segments. Drinking to thirst was the most common (p < 0.01) drinking strategy (used by 67.0% during at least one segment) and most runners (95.6%) used sodium supplementation during at least one segment. There was no difference in the extent of weight loss (mean 2.0-3.1%) or the weight change pattern when comparing groups using different hydration strategies. Among top-10 finishers, half had lost more than 2% of starting body weight by 90 km. We conclude that weight loss greater than 2% does not necessarily have adverse consequences on performance, and use of sodium supplements or drinking beyond thirst is not required to maintain hydration during ultra-endurance events with high thermal stress.
authors.affiliation: a Department of Physical Medicine & Rehabilitation, Department of Veterans Affairs , Northern California Health Care System, and University of California Davis Medical Center , Sacramento , CA , USA.
authors.forename: Martin D
authors.initials: MD
authors.lastname: Hoffman
authors.forename: Kristin J
authors.initials: KJ
authors.lastname: Stuempfle
mesh_terms: D001628:Beverages; D003681:Dehydration / Q000209:etiology / Q000517:prevention & control*; D019587:Dietary Supplements; D004326:Drinking / Q000502:physiology*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D012420:Running / Q000502:physiology*; D012964:Sodium; D011795:Surveys and Questionnaires; D013894:Thirst; D014882:Water-Electrolyte Balance; D015431:Weight Loss / Q000502:physiology*
chemical_list: D012964:Sodium
keywords: dehydration; endurance exercise; exercise; sodium; water-electrolyte imbalance