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Food During Exercise

If you are going to exercise for more than an hour, you can increase your endurance by eating every 15 to 20 minutes. A feeling of general tiredness during exercise is usually caused by low levels of stored sugar in your liver, while a feeling of muscle fatigue is usually caused by low levels of stored muscle sugar.

Your brain gets more than 98 percent of its energy from sugar flowing to it in the bloodstream, but there is only enough sugar in your bloodstream to last for three minutes. Your liver must constantly release sugar from its cells into your bloodstream. However, there is only enough energy in your liver to last about 12 hours without replenishment.

Your muscles get their energy from many sources: sugar and fat stored in them, and sugar, fat or protein in the bloodstream. When your muscles run out of their stored sugar supply, they can hurt and feel tired. You can increase endurance by eating frequently, and you can eat whatever you like: nuts, fresh or dried fruits, chicken, sandwiches or anything else. The amount of sugar you get in sports drinks is not adequate to support strenuous exercise for long periods of time.

Checked 9/29/08

May 11th, 2013
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About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities. Read More
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