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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.
This material is the result of work supported with resources and the use of facilities at the VA Northern California Health Care System. The work was also supported by the Western States Endurance Run Foundation. We thank the following individuals for their assistance: Ali Alvandi, Dr Kim Corrigan, Dr Kevin Fogard, Dr Tracy Høeg, Dr Mark Kasmer, Rachel Lord, Dr Christine Mathiesen, Dr. Vanessa McGowan, Kevin Mullins, Dr Ken Onishi, Dr David Oxborough, Dr David Paris, Professor John Somauroo, Carol Steinbrecher, Steve Steinbrecher, Mike Stembridge, Taylor Valentino and Lisa Weiss. The contents reported here do not represent the views of the Department of Veterans Affairs or the United States Government.