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Feeding Your Muscles For Endurance

Ever come back from a workout glowing with an endorphin-stoked essence that dishes out mellow spoonfuls of athletic satisfaction, only to start succumbing to a fatigue that suggests the need for a regenerative sports potion? Consuming the optimal combination of post-exercise nutrients is crucial for keeping muscles well-nourished and maximizing your longterm fitness. A key component within this fitness puzzle is glycogen, stored carbohydrates that the liver and the muscles create and stash for conversion into energy during aerobic exercise.

As Edmund R. Burke, PhD, director of the Exercise Science Program at the University of Colorado, points out in his book Optimal Muscle Recovery (Avery), "Clinical studies have proven that athletes who consume carbohydrates within two hours after exercise are able to more completely restore their muscles' glycogen levels." In support of this need to quickly consume carbohydrates, researchers at the University of Illinois found that laboratory animals who exercised until their glycogen vanished recovered more quickly with sugar water. In results presented at the American Society for Nutritional Sciences (April 6, 1999), they found that they recovered 60% of their glycogen in an hour and 100% within four hours. Animals who only drank water took eight hours or more to recover their glycogen and muscle protein synthesis.

Protein Provides "OOOmph"
However, merely binging on sugar (the ultimate refined carbohydrate) or other sweets after working out will not maximize glycogen creation and storage. To most effectively store muscular energy, boosting "insulin is essential," Dr. Burke points out. Insulin is a hormone secreted by the pancreas that helps move glucose from the blood stream and into the muscles. "Studies have shown that protein, when combined with carbohydrate, almost doubles the insulin response and increases the rate of glycogen synthesis by 30%," notes Dr. Burke.

Burke cautions, however, than an overindulgence in protein provokes the body's production of a biochemical called cholecystokinin (CCK). CCK slows down the rate at which food and fluid moves from the stomach and into the intestines for absorption. This process then hinders absorption of both carbohydrates and water, consequently slowing your recovery.

Mixing Carbs and Protein
Burke cites research that suggests the best recovery nutrient combination consists of four times as much carbohydrate as protein. (He says that if you take in 56 grams of carbs after exercise, you should accompany this with about 14 grams of protein.) This is supported by research by John Ivy, PhD, of the University of Texas who gave athletes protein in the form of the amino acid arginine after exercise. Arginine helps prod the pancreas to secrete more insulin and also takes part in other muscle functions.

When athletes took arginine with their carbohydrate, their glycogen recovery jumped by more than a third. One of the most important elements to remember in your after-exercise munchies: Eat as soon as possible after finishing a workout. This may be difficult for you if you find that exercise blunts your appetite. Dr. Burke believes you should limit your fat consumption at this time since fat also slows down the rate at which food moves through your stomach.

One effective way to eat protein with your sugar is to consume nonfat yogurt sweetened with fruit and fruit juice. A tuna sandwich (skip the fatty mayo) along with plenty of fruit juice and fruit also provides protein with carbohydrates.

Keep On Eating
You should also plan on consuming another meal two to four hours after your workout, in Dr. Burke's view, designed to provide further recovery. "The meal should be comprised of 60 to 65% of calories from carbohydrates, 20 to 25% from fat and about 15% from protein," he suggests. But while you're doing all this eating, don't overindulge - especially if you're an aging athlete. Research on lab animals at the University of Wisconsin found that restricting calories limited muscle loss in aging animals. So keep that fork under control!
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Taken from Swim Sport, August 1999