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Muscle Cramps in Endurance Events

If you've ever developed severe muscle cramps during long-term exercise, the odds are that you never found out why it happened. Doctors in South Africa studied triathletes and found that most of the time, the muscles cramps were not caused by dehydration, thyroid disease, blocked blood flow, nerve damage, or mineral abnormalities of calcium, sodium, magnesium or potassium (Medicine & Science in Sports & Exercise, July 2005).

The athletes with cramps had normal electrolytes and did not lose more fluid during exercise than those who did not suffer cramps. The researchers showed that the most likely cause is muscle fatigue or tearing of the muscle itself. Electromyograph (EMG) studies at one to five minutes showed markedly elevated electrical activity of the nerves controlling the cramped muscles. Therefore muscle cramps during long distance athletic events appeared to be caused by exercise-induced damage to the muscles themselves. If this is true, muscle cramps during endurance events can be prevented by slowing down when you feel excessive soreness in one muscle group or straining in a muscle. Of course, competitive athletes will not do this, and they pay for it with muscle cramps.


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Dear Dr. Mirkin: Why are diabetics at such high risk for heart attacks?

A recent study from Washington University in St Louis may explain why more than 75 percent of diabetics die of heart disease (Journal for the American College of Cardiology, February 7, 2006). The heart muscle of diabetics uses a much higher percentage of fat for energy than that of non-diabetics, to markedly increase risk for heart attacks.

The energy source for heart muscle is mostly sugar and fat, and to a lesser degree, protein. Muscles need far more oxygen to process fat than to process sugar. The blood supply to heart muscle comes from large arteries on the outside of the heart. Diabetics have narrowed arteries because high blood sugar levels cause plaques to form and reduce the diameter of the coronary arteries. The increased need for blood flow from burning fat and the decreased blood flow from narrowed arteries put diabetics at very high risk for heart attacks, heart failure and sudden death. The increased use of oxygen increases blood levels of oxidants that further damage the inner linings of arteries.

Type 2 diabetes can be prevented
If you are already diabetic, please read Treatment of insulin resistance


Dear Dr. Mirkin: Will training for a triathalon make me a better cyclist?

World-class triathletes are slower runners, swimmers and cyclists than athletes who compete in only one sport. A study from the University of Toulon-Var in France shows that swimming before cycling slows you down (Canadian Journal of Applied Physiology, August 2005). Well-trained male triathletes pedaled for 30 minutes on a stationary bicycle at 75 percent of their maximal aerobic power, with a cadence of 95 revolutions per minute. Later they did the same exercise after swimming 1500 meters.

After swimming, they had a 13 percent reduction in efficiency, and significantly higher blood lactate levels. Fatigue from swimming caused them to lose their efficient form so that they had to work much harder to maintain the same pace. Fatigue has the same effect on all athletes. A fresh field goal kicker in football will perform better than one who has played the entire game. Triathletes will always swim, run and cycle slower than comparable athletes training for only one sport. However, triathletes have fewer injuries.


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Juliet’s Black Bean and Corn Soup
Harlan’s Dad’s Chili

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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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