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Jenna Gigliotti currently works as a physician assistant in a family medicine office where she addresses the root cause of illness and incorporates lifestyle management for both acute and chronic conditions. She has completed a Board Certification in Lifestyle Medicine through the American College of Lifestyle Medicine and a Certificate in Plant-Based Nutrition. She continues to increase her knowledge and expertise in mindfulness, sleep hygiene, and physical activity.‍

Most people associate dehydration with hot weather but it is just as easy to become dehydrated when it is cold out. There are several unique factors of frigid temperatures that make dehydration a very real concern during cold weather exercise.

First, the body’s thirst response is diminished up to 40% in the cold, so it can be harder to remember to drink enough without the body’s full thirst drive (1). Second, sweat evaporates more quickly in drier air (colder temps usually mean drier air too), so it may feel like you are sweating less and make you think you do not need to drink as much. But you are still sweating and using water for metabolic processes in the body while you exert yourself- and you are likely sweating and exerting yourself much more than you think.

According to one study, your body may be working up 10-40% harder in cold weather, in part due to wearing extra (heavier) layers of clothing and running in a headwind or snow with poor traction (2). Fluid loss via sweat in cold weather can equal or surpass losses in other temperatures, even if it doesn’t feel like you get as sweaty in the cold. Third, sweat is not the only way the body loses water- respiration also accounts for a significant amount of water loss. Cold and dry air increases the amount of water lost during respiration. This water loss is visible in the cold- when you can “see your breath”, you are seeing the water vapor that your body is losing. Higher intensity of exercise increases the rate and depth of breathing which further increases this respiratory water loss. Thus, the colder the temperature, the drier the air (an added issue at high altitude), and the more intense the exercise, the more water you lose when breathing (3). Due to all these factors, it is important to focus on adequate hydration in cold weather to optimize performance and recovery.

Cold Weather Hydration Tips

• A general rule of thumb is to drink at least half of your body weight in ounces of water each day at baseline, plus more water for exercise, effort, temperature, humidity, altitude, etc.
• Don’t rely on thirst to tell you when to drink water - monitoring urine color and frequency are much more reliable markers of hydration status.
• Drink room temperature or warm water instead of cold water to hydrate and stay warm pre-and post-run. If warmer temperature water is still unappealing, try some herbal tea, hot apple cider, or broth to hydrate with both warmth and flavor. If you are going to be out exercising for much more than an hour, you could even try carrying some of these warm beverages in your bottles! And still remember those electrolytes too if you are doing an extended effort in the cold. To help warm you up after a cold weather workout, try hot chocolate instead of chocolate milk to speed up the rewarming and recovery process.
• If you still struggle drinking enough fluids in cold weather, try eating more fresh fruits and vegetables which have high water content and can also help hydrate you. Adding broth-rich soups to the menu more frequently in cold weather can also help add to your fluid consumption.
  

References

1. Kenefick RW, Hazzard MP, Mahood NV, Castellani JW. Thirst sensations and AVP responses at rest and during exercise-cold exposure. Med Sci Sports Exerc. 2004;36(9):1528-1534. doi:10.1249/01.mss.0000139901.63911.75
2. Castellani JW, Young AJ, Ducharme MB, et al. American College of Sports Medicine position stand: prevention of cold injuries during exercise. Med Sci Sports Exerc. 2006;38(11):2012-2029. doi:10.1249/01.mss.0000241641.75101.64
3. Freund BJ, Young AJ. Environmental influences body fluid balance during exercise:cold exposure. In: Buskirk ER, Puhl SM, editors. Body fluid balance: exercise and sport. New York: CRC Press; 1996. pp. 159–181.

— Jenna Gigliotti