Most people don’t drink enough fluid when they exercise. This can quickly lead to dehydration and a rise in core body temperature, especially in warm weather. This rise in body temperature increases heart rate, puts additional strain on the heart and places you at risk for heat exhaustion and heat stroke. It also reduces exercise performance and causes you to fatigue more quickly. Replacing fluids lost through sweating also reduces how hard exercise feels and makes it seem less unpleasant. Fortunately, there’s an easy way to prevent dehydration. Drink more fluids – but what kind of fluid and how much?
Exercise Hydration: Don’t Depend on Thirst to Tell You When You Need to Drink
When you work out, do you only stop to drink water when you’re thirsty? Thirst is a poor indicator of fluid status, especially in older people. In fact, you may not experience the sensation of thirst until you’re dehydrated by 1 to 2%. By this time, your exercise performance is suffering, and you feel fatigued and may be lightheaded and have a headache or dry mouth. If you stop to drink at the point you’re thirsty, you’ve waited too long. It takes time to restore fluid balance once you drink fluid and you’ll probably feel worse before you feel better. The key is to replace fluids regularly so you don’t become thirsty or dehydrated.
Exercise Hydration Tips: How to Prevent Dehydration
For optimal exercise hydration, increase your fluid intake a few hours before your workout. The American College of Sports Medicine recommends drinking 17 ounces of cool or cold fluids two hours before exercising. Sports drinks that have carbohydrates and added electrolytes aren’t necessary unless you’ll be exercising for longer than one hour. Drink another cup of fluid 10 to 20 minutes before beginning your workout and an additional cup of fluid every 20 minutes during exercise to replace fluid lost through sweating. After completing your workout, weigh yourself on a scale and drink 2.5 cups of fluid for each pound of weight loss.
When Should You Drink a Sports Drink Instead?
Water is usually adequate unless you’ll be exercising at a moderate intensity or greater for more than an hour. In this case, sports drinks have the advantage of helping to delay fatigue. Sports drinks also contain sodium, which you may need during periods of long, intense exercise in a warm environment. If you drink large quantities of water without replacing sodium you run the risk of “water intoxication”, a condition where sodium levels become too low in the blood. This can be dangerous.
If you don’t want to spend the money on a commercial sports drink, you can make your own by diluting fruit juice with water. For every two liters of diluted fruit juice, add a quarter teaspoon of salt. Some people experience stomach discomfort and gas from the fructose in fruit juice. If so, dilute the fruit juice more until you find a concentration that works for you.
Exercise Hydration is Important
Don’t let dehydration affect your workout or put you at risk for heat-related illness. Increase your fluid intake at least 2 hours before, and follow these exercise hydration tips for replacing fluids during and after exercise. You’ll feel better, perform better and be safer when you exercise.
Exercise Physiology: Theory and Application to Fitness and Performance. Seventh Edition. Powers and Howley. 2009.
American College of Sports Medicine. “Exercise and Fluid Replacement”