Athletes who train in the winter (hikers, runners, hockey players, and skiers commonly experience dehydration. These athletes tend to skimp on fluid intake, because urinating often requires shedding layers of clothing or ending a workout early. In addition in the cold air, these athletes may not think to drink. However, dehydration can hurt performance and contribute to high-altitude illness. Therefore, it’s important to take the extra efforts to hydrate during winter training and activities.
In addition to inadequate fluid intake, fluid losses can be unexpectedly high in the winter. Breathing when the environment is cold and dry requires the body to humidify and warm the air. Hence, significant amounts of water are lost during exhalation. Plus, athletes who overdress for their activities create significant sweat losses. Sweat losses can range from 1 to 4 liters per hour depending on heat, fitness level, muscle mass…etc. To learn your sweat rate loss follow the guide below.
Weigh yourself (naked) before and after a work out (example = one hour). Each pound lost represents approximately 1 liter (or 2 cups) sweat. Example: If you lost 2 pounds during exercise, but also drank 2 cups of water or sports drink during that exercise, then your overall sweat rate would be 6 cups per hour (2 pounds x 2 cups/pound + 2 cups = 6 cups/hour).
Fluid physiology (the basics): The kidneys clear fluids in 45 to 90 minutes. Therefore, if you’re planning your workout you should tank up 1.5 to 2 hours before exercise so that you’ll have time to urinate before starting. Then you can optimize your fluid intake by drinking more fluids immediately before exercise (expect to have to urinate again in 45-90 minutes).
The bottom line: Winter athletes need to consume enough fluids to result in urine that is light colored, not dark and concentrated. Be sure to replace every pound lost with liquid (water is a good thirst quencher but not a great rehydrator – better to chose something with sodium and electrolytes).
Naomi L. Sklar, MD
Vitality Sports Medicine, PO BOX 1601 Wilson, WY 83014
Teton Valley Hospital, 120 East Howard Ave, Driggs, ID 83422