How to Fuel on a Run

You've seen them in running stores: Nutritional supplements--gels, energy bars, sports drinks--that promise they can help you run faster and longer.

As a general rule of thumb, if you jog for 30 minutes, you only need to drink water. But if you're running longer than an hour, you need carbohydrates, says Kristine Clark, Ph.D., R.D., and the director of sports nutrition at Penn State University. That's because your body's blood glucose and muscle carbohydrate stores (glycogen)--the preferred fuel for hard-working muscles--become depleted in as little as 60 minutes.

Numerous studies have shown "the quick-digesting carbs in energy products boost blood glucose and help spare muscle glycogen during a long run," says Clark. The benefit: You get an energy jolt that helps you keep running. But with so many options, what should you consume? Use this guide to find what's right for you.


With a mix of water and carbohydrates, sports drinks are quick-and-easy fuel that boost energy and keep you hydrated.

Why they work: To perform your best, you need between 30 and 60 grams of carbohydrate for each hour of exercise. Sports drinks like Hammer HEED, Powerade and Gatorade supply a blend of carbs, such as maltodextrin and glucose, plus water and sodium to prevent dehydration, says Nancy Clark, R.D., author of Nancy Clark's Sports Nutrition Guidebook. Besides helping replace what is lost through sweat, "sodium enhances the retention of fluids in the body," she says.

Choose the best: "Sports drinks should have a 6 to 8 percent carbohydrate concentration for the best absorption of the sugars and water," says Clark. To calculate this, divide the number of grams of carbohydrate in an 8-ounce serving by 2.4. For example, if a sports drink has 15 grams of carbohydrate per 8-ounce serving, the carbohydrate percentage is 6.25 percent.

Choose a sports drink with at least 110 mg of sodium per 8-ounce serving, a vital mineral you lose when you sweat. Some sports drinks, such as Gatorade Endurance or PowerBar Endurance, offer the same amount of carbs as regular sports drinks, but have an extra dose of sodium and potassium. "If you're exercising three or more hours or sweating buckets on a humid day, you may want one of these higher-sodium products," says Clark.

You also may consider sipping sports drinks with protein. University of Texas researchers found when subjects consumed a sports drink with added protein, they performed better during an endurance test than when they drank a carbohydrate-only beverage. If you opt for one of these, look for a 4:1 carb-to-protein ratio like that found in Accelerade drinks.

Keep in mind: Take care when making these drinks from powder, as over-concentrated mixes can cause stomach distress. Remember, these are basically sugar drinks with little nutritional value; drink them only for training.

How to use them: Drink at least two 8-ounce servings every hour to get the minimum 30 grams of carbohydrate.


The convenient single-serving packets make gels a popular on-the-run fuel source.

Why they work: Like sports drinks, gels such as GU, CLIF Shot and Hammer HEED have sugars and maltodextrins to provide fuel. "Energy gels provide a super-concentrated source of fast-acting carbohydrates," says Clark. Gels require no chewing--a plus when you're running hard.

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