Air during the winter months is generally much drier than during the summer. As you inhale the cold, dry air during an activity, it is warmed and humidified as it passes through your respiratory system. This creates an increase in water loss through your respiratory system, therefore increasing your need to replace fluids during and after activity. The longer the activity, the greater the risk for water loss, creating an increased risk of dehydration. Clothing can also play a role. If you are dressing properly during the winter, you will have a moisture-wicking base layer that will whisk away any moisture on your skin. This is an advantage to feeling warm during your run, but a disadvantage from a hydration standpoint because you don’t feel as sweaty after your run and may not feel the need to re-hydrate. The very best way to ensure proper hydration is to do the following:
1. Make sure you properly hydrate before your run. A general recommendation from the American College of Sports Medicine Position Stand is to drink five to seven milliliters of water or sports drink per kilogram body weight (about one ounce per every 10 pounds of body weight) about four hours before exercise begins. The best rule of thumb is to let physiologic symptoms of thirst (dry mouth, craving water) or overdrinking (nausea, sloshing) and evaluating color of urine (it should be light yellow or clear) guide hydration prior to your run.
2. While physiologic symptoms are best to guide hydration prior to your run, research shows that it is often not the best indicator during a run. It is recommended to perform a sweat test often and ensure you are replacing the correct amount of fluids lost during your activity. You can perform a sweat test by weighing yourself before and after exercising for one hour. Keep track of your intake during the activity (one medium gulp is roughly equivalent to one ounce). Also, keep track of any fluid losses other than through sweat (hopefully you don’t have to use the restroom during that one-hour test). Multiply the pounds lost by 16 to convert to total ounces lost. That is how many ounces that should be replaced each hour during your cold weather activity. I usually recommend dividing that number by four and aim to take in water every 15 minutes. The number will vary depending on many conditions so it is recommended to perform a sweat test often.
3. After exercise, it is important to replace fluids and electrolyte deficits. The recommendation from the American College of Sports Medicine Position Stand is to replace 1.5 liters of fluid per kilogram weight lost. Electrolytes can be replaced by consuming snacks and beverages with sodium.
4. Watch for symptoms of dehydration: thirst, unusual fatigue, lightheadedness, headache, dark urine, dry mouth, infrequent urination or an unusually rapid heartbeat. Overdrinking can be an issue as well causing a dangerous condition called hyponatremia. Symptoms of overdrinking include sloshing, nausea and dizziness. To dial in your hydration plan, consult a registered dietitian. They will not only help you figure out what to drink during training and on race day, but can assist with proper fueling as well.
This article originally appeared at Trainingpeaks.com.