Cold weather brings about the common misconception that rehydration during exercise isn’t as important as during hot weather. While it’s true that typical sweat losses are reduced in cooler weather, the additional clothing worn during winter sports actually contributes to significant fluid and electrolyte loss via sweat.
Cold weather studies at the University of New Hampshire, in fact, confirm an increased risk for dehydration. “People just don’t feel as thirsty when the weather is cold,” says Robert Kenefick, UNH associate professor of kinesiology. “When they don’t feel thirsty, they don’t drink as much, and this can cause dehydration.”
Robert Kenefick’s cold weather study, published in the journal Medicine & Science in Sports & Exercise, had participants exercise on treadmills in cold chambers and found the participant’s thirst sensation to be reduced by as much as 40 percent. Kenefick concluded that this result is due to our bodies naturally decreasing outward blood flow in order to maintain the warmth of vital organs. Consequently, our brains are slower to become aware of a temperature decrease in our extremities and, as a result, the hormones that signal our kidneys to conserve fluid are not released at the same rate they would be in warmer weather. He stated, “this can all add up to as much as an eight percent drop in fluid body mass during periods of high activity in cold weather. To put that in perspective, symptoms of mild dehydration start to show after just a two percent loss in body fluids.”
The Mayo Clinic advises athletes to stay well hydrated when exercising in cold weather just as you do when exercising in warm weather. Drink water and continue your typical electrolyte replenishment routine before, during and after your workout, even if you don’t feel thirsty. People are just as vulnerable to dehydration and hyponatremia in the cool climates, but the effects can be less apparent. The suggested intake of 1-2 SaltStick Caps per hour remains appropriate during winter exercise while consuming appropriate amounts of fluid and caloric intake. Make sure you are able to finish that ski day strong, don’t neglect proper nutrition during the winter!