Hydrating for Exercise (water vs sports drinks)

Dear Doctors Column, June 21, 2010


Do sports drinks have any benefits compared with water when I’m trying to stay hydrated during a workout?


If you’re exercising at a moderate intensity for an hour or less, water is the best choice for hydration before and during a workout. You’ll save money if you choose tap water instead of bottled water (25% of bottled water is repackaged tap water) or sports drinks. Drinking water rather than sports drinks also saves calories – water is calorie free, while sports drinks typically pack 50 to 60 calories (and sometimes more) into a serving, and a 16-ounce bottle is 2 to 3 servings.

Water, however, will only provide the hydration you need if you drink enough. Some people find the taste of water bland and this can make it hard to drink the amount needed to stay fully hydrated. People tend to consume a greater volume of liquid when drinking sports drinks because they prefer the taste to water, and this leads to better hydration.

Fitness experts recommend drinking 8 to 16 ounces of water 2 hours before a workout and another 8 to 16 ounces 30 minutes before exercising. When you’re working out for more than 30 minutes you’ll need to drink another 3 to 6 ounces of liquid every 15 to 20 minutes. If you’re working at a high intensity, you may need 6 to 12 ounces every 15 to 20 minutes, especially if you’re exercising in high heat and humidity, which can dehydrate you in as few as 15 minutes.

For people exercising for more than 60 minutes, at a high intensity, or both, sports drinks do offer some benefits. These drinks provide both carbohydrates and electrolytes. The carbohydrates, typically glucose, fructose, or fructose, help delay muscle fatigue, while the electrolytes help move fluids quickly into the bloodstream and replace some of the sodium lost in sweat.

Fruit juices contain too much carbohydrate in the form of fructose, or fruit sugar, which can reduce the rate of water absorbed by cells. Avoid drinks that contain caffeine, such as soda and coffee. Caffeine is a diuretic, meaning it pulls water from the bloodstream.

The body loses a significant amount of fluid during exercise and staying adequately hydrated is important for both performance and safety. Mild dehydration can cause dry mouth, headaches, weakness, and fatigue, and cramps. People who become severely dehydrated need immediate medical attention. Extreme thirst, no urine output, fainting or dizziness, a rapid heart rate, low blood pressure, and confusion are symptoms of severe dehydration.

To prevent dehydration it’s important to drink before you become thirsty. That’s why you need to load up on liquid before a workout. Once you start to lose fluid it can hard be hard to take in enough liquid to stay hydrated. Water and sports drinks are your best choices for hydration, so drink up!


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