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Warming Up and Stretching May Impair Performance in Competition

Have you watched football players, sprinters and other athletes warming up and stretching before competitions? Two studies, one from Louisiana State University and one from Liverpool University in England, show that they may be harming their performance (Journal of Sports Science, May 2005).

In the first study, elite college sprinters were timed in 20 meter sprints, with and without prior multiple 30-second stretches of their leg muscles. As was expected, both active and passive stretching slowed them down. Many previous studies show that you cannot lift your maximum weight after a muscle is pulled and stretched. Other studies have failed to show that stretching prevents injuries. This study does not tell you to stop stretching completely because there is solid data to show that stretching makes you a better athlete. Stretching elongates tendons and the longer the tendon, the greater force a muscle can exert around a joint to make you stronger and faster. However, this study suggests that athletes should not stretch before competitions.

The English study shows that warming up limits how far you can run. Runners alternated 30 seconds of very fast runs on a treadmill with 30 seconds of running very slowly until they were exhausted. They tired earlier after having their legs heated passively and also after taking a long warm up run before testing. At temperatures of about 70 degrees F., both active and passive heating raised both muscle and body temperatures, which uses up muscle glycogen faster and tires runners earlier. Since warming up has been shown to help prevent injuries, it may be good idea to warming up before power events of short duration, but not before competitions that last for several hours.


Dear Dr. Mirkin: Should a diabetic eat fruits and root vegetables?

Yes; root vegetables and fruits are rich sources of vitamins, minerals, phytochemicals and fiber. Many studies show that diabetics who do not eat fruit and root vegetables, such as potatoes, carrots or beets, are at increased risk for heart attacks and strokes. Recent studies from Oxford University in England and Arizona State University show that diabetics should eat fruits and root vegetables with other foods to slow the rise in blood sugar that can cause cell damage (European Journal of Clinical Nutrition, January 2006; Journal of the American Dietetic Association, December, 2005).

Diabetics are at high risk for heart attacks, strokes, blindness, deafness, kidney failure and damage to virtually every tissue in their bodies. These serious side effects are caused by blood sugar levels rising too high after meals. When you eat food, it passes into the stomach where the pyloric sphincter closes and prevents food from entering the intestines. The stomach squeezes and mixes its contents and only when solid food is converted to a thick soup does the pyloric sphincter open and permit food to pass into the intestines, where sugar is absorbed immediately to cause a high rise in blood sugar. If you eat nuts along with the potatoes or fruits, the fat in the nuts keeps other foods eaten with them in the stomach for a longer period of time and therefore blood sugar levels do not rise as quickly. Any slowly-digested foods that contain fats or protein will have the same effect, so eat your fruits and root vegetables with other foods, not alone as snacks. Read my Treatment of Insulin Resistance; the same advice applies to both diabetics and pre-diabetics.


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Dear Dr. Mirkin: Does an enlarged heart always indicate serious problems?

Sometimes doctors mistake a large, strong healthy heart caused by vigorous exercise with the large, weak, sick heart of cardiomyopathy. A report from University College London Hospitals describes the case of a professional athlete who was prohibited from playing football because doctors didn’t order the right tests (European Journal of Echocardiology, August 2005). In cardiomyopathy, the enlargement is caused by the heart’s inability to pump blood through the body at rest because of poor pumping power and inability to fill adequately with blood. A person with this condition can die during exercise. On the other hand, people who exercise vigorously over many years can develop a very large muscular heart that is stronger than normal and far less likely to suffer any disease. If this patient had an echocardiogram and treadmill exercise tests read by a physician experienced with athletes, he would not have been diagnosed with cardiomyopathy. More


Recipe of the Week:
Spring is asparagus time!
Steam them until just tender and season with a little lemon juice if you like, add them to any salad, or use them in:

Seafood "Stir Fry"

List of Diana's Healthful Recipes

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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