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Do Not Limit Calories Before Competition

Most athletes know that lack of fluids weakens and tires them, so they take adequate amount of fluids, before, during and after competitions. However, many do not know how much they need extra calories. They often are told incorrectly that the human body as so much fat on board that lack of calories is not a significant problem. Researchers at the University of Wales in the United Kingdom found that moderate calorie restriction two days prior to competition slows down endurance far more than reduced fluid intake over that same period (Medicine and Science in Sports and Exercise, February 2007). Moderate dehydration does not harm performance until a person becomes severely dehydrated. On the other hand, lack of calories stops you cold in your tracks.

Dehydration does not limit endurance until a person loses enough fluid to decrease blood volume, which takes a long time. However, endurance during exercise depends on having enough sugar stored in your muscles. When you exercise, you get energy from fat and sugar stored in muscles, fat and sugar from the bloodstream, and to a lesser extent, from protein. When your muscles run out of their stored sugar, they can hurt and you will find it more difficult to coordinate them. This happens no matter how much energy you have stored in body fat, which is virtually limitless during almost all athletic events. So a major nutritional principle of endurance exercise is to store as much sugar in muscles as possible and preserve that sugar supply for as long as possible. When you reduce calorie intake, you reduce your stored muscle sugar supply, so you should never fast or reduce calorie intake prior to athletic competition. In a few sports, athletes must lose weight so they can compete in a lower weight class, but they can compensate to some extent by eating as much as possible just before they start their competition.

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Dear Dr. Mirkin: Does the loss of muscle mass as we age come just from lack of exercise?

Many older people are so weak that they move slowly, are terribly uncoordinated and often fall and break their bones. A study from France shows that part of this problem can be caused by faulty chewing (American Journal of Clinical Nutrition, May 2007).

As almost all people age, they lose muscle tissue and become weaker. Muscles are built from the protein digested from food. The authors measured protein absorption in older people by feeding them radioactive leucine and then measuring the amount in their blood. Half the subjects had normal teeth and half had full dentures. Those who lost all their teeth had far lower absorption of the protein that they ate, absorbing only 30 percent compared to 48 percent for those who had their own teeth. This study shows that the ability to chew food affects nutritional status and may be a major factor in the health of elderly people.

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Dear Dr. Mirkin: Is jumping rope a good way to become fit?

To use rope-jumping for fitness, you need to be skilled enough to jump continuously for twenty to thirty minutes, and jumping that long and fast requires that you be in good shape. All you need is a ten-foot rope. The ends of the rope should barely reach your armpits when you stand on the middle of it. You don't need special shoes, but sandals or loose shoes are likely to cause tripping. Start out by spinning the rope forward so you can see it as it passes. Bend your knees to absorb the shock of landing and protect the force of your feet striking the ground. To keep yourself from falling, bend slightly forward at the waist. Start out gradually and work up to thirty minutes three times a week.

The fitness benefit from any exercise depends on how fast you move, whether it's jumping, running, cycling or any other activity. Jumping rope has to be a vigorous sport, because you must spin the rope at least 80 times a minute to keep it from tangling. Most people use more energy when they jump rope than when they run. Jumping 80 times a minute uses the same amount of energy as running a mile in less than eight minutes, which is a rapid pace for most people. If you enjoy rope jumping, do it at a speed that is comfortable to you and stop when you feel discomfort.

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Blueberries are here! Enjoy them right from the box, or in --

Fresh Fruit Bowl

Diana has updated her list of Favorite Kitchen Tools
and her Cookbook List

You'll find lots of recipes and helpful tips in The Good Food Book - it's FREE

June 26th, 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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