Sugar during your workouts

Dr. Gabe Mirkin's Fitness and Health E-Zine

Sugar During Exercise Increases Power and Endurance


July 26, 2009

A study from Copenhagen, Denmark shows that taking sugar while you exercise increases the amount of training you can do, and does not lessen the benefits of your increased training (Journal of Applied Physiology, June 2009). In this study, men trained one leg while ingesting a 6 percent sugar drink and the other leg while taking an artificially sweetened (sugarless) drink, two hours a day, on alternate days, five days a week. The legs trained with sugar had 14 percent more power and a 30 percent greater time to exhaustion.

Athletes in sports requiring endurance need to train in their sport many hours each day. They damage their muscles by taking a hard workout on one day, feel sore on the next, and then take less intense workouts for as many days as it takes for the muscles to heal and the soreness to go away. The more intense the training workout without injury, the more intensely they can compete. The longer they can go on their less intense recovery days, the tougher their muscles become to withstand the tremendous forces on them during their hard workouts and during competition.

Anything that can increase the intensity of their hard days or amount of work they can do on their recovery days will make them better in competition. Running out of muscle sugar makes you feel tired. So anything that preserves stored sugar in muscles during a workout will help you exercise longer. This study shows that taking sugar regularly during workouts allows you to extend the amount of training without lessening the benefits that you receive from the extra work.

The question had been asked whether restricting sugar during training could enhance performance by teaching the muscles to get along with less sugar. These authors showed that the enzymes used to convert sugar and fat to energy function just as well when sugar is taken continuously during exercise. The muscles trained on sugar had no loss in the amount of stored sugar or the ability to convert food to energy.

Another study showed that taking a drink containing both protein and sugar every three miles and at the finish of a 36-mile bicycle time trial was far more effective than a drink containing just sugar in 1) riding faster at the end of the time trial, 2) preventing next-day muscle soreness and 3) lessening muscle damage, as measured by a blood test called CPk (International Journal of Sport Nutrition and Exercise Metabolism, April 2009). A protein-sugar drink taken immediately after intense exercise also hastens healing of the muscles damaged by hard exercise (Journal of Applied Physiology, April 2009).

Taking refined carbohydrates (sugar or flour) when you are not exercising can cause a high rise in blood sugar that increases risk for diabetes and heart attacks. Contracting muscles remove sugar so fast from the bloodstream that blood sugar usually does not rise too high during exercise and for up to half an hour after you finish exercising.