Hydration strategies, weight change and performance in a 161 km ultramarathon

Res Sports Med. 2014;22(3):213-25. doi: 10.1080/15438627.2014.915838.


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.

Keywords: dehydration; endurance exercise; exercise; sodium; water-electrolyte imbalance.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Beverages
  • Dehydration / etiology
  • Dehydration / prevention & control*
  • Dietary Supplements
  • Drinking / physiology*
  • Female
  • Hot Temperature
  • Humans
  • Male
  • Physical Endurance / physiology*
  • Running / physiology*
  • Sodium
  • Surveys and Questionnaires
  • Thirst
  • Water-Electrolyte Balance
  • Weight Loss / physiology*


  • Sodium