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Caffeine Increases Endurance

Caffeinated drinks increase endurance during long events such as a marathon, triathalon or bicycle race. A study from the University of Birmingham in England shows that caffeine helps the body use more carbohydrates from drinks that you take during exercise (Journal of Applied Physiology, June 2006). Those who took sugared drinks with caffeine were able to absorb and use 26 percent more of the ingested sugar than those who took the same drinks without caffeine.

Previous studies show that caffeine helps athletes run faster in both short and long-distance races. In short races, it makes athletes faster by causing the brain to send messages along nerves to cause a greater percentage of muscle fibers to contract at the same time. In longer races, it delays fatigue by preserving stored muscle sugar. Muscles get their energy from sugar and fat in the bloodstream, and from sugar, fat and protein stored in the muscles. When muscles run out of their stored sugar, they hurt and become more difficult to coordinate. Caffeine causes muscles to burn more fat, thus sparing stored muscle sugar to delay fatigue.

Nobody really knows how much caffeine you can take in without harming yourself. At rest, caffeine is a diuretic, but during exercise it does not increase urination. Caffeine is a potent stimulant that can cause irregular heartbeats in people who already have heart disease, and raise blood pressure in people with hypertension. Most research shows that it doesn't take much more than one or two soft drinks to increase endurance. Caffeine loses its beneficial effects with repeated exposure, so athletes who want to gain maximum advantage from caffeine during competition should avoid drinking caffeinated beverages when they are not exercising.


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Dear Dr. Mirkin: Is diabetes more likely to be genetic or environmental?

A study from the University of Wisconsin shows that Pima Indians in America are more than five times more likely to develop diabetes than their relatives in Mexico (Diabetes Care, August 2006). Pima Indians in Arizona have been shown by DNA typing to be very closely related to Pima Indians in the Sierra Madre mountains of Mexico. However, only 8.9 percent of Mexican Pimas developed diabetes, compared to 38 percent of those in the United States.

Obesity is a major risk factor for diabetes, but both populations were similarly obese. About eight percent of the Pima men and 20 percent the Pima women suffered from obesity. However, the Mexican Pimas were far more active than the American ones and ate far fewer refined carbohydrates. This study shows that diabetes is more an environmental disease than just a genetic one. Your genes determine how you respond to the environment. Since this study agrees with hundreds of others, I recommend that everyone should exercise and limit refined carbohydrates such as flour and sugar, whether or not there is a family history of diabetes.


Dear Dr. Mirkin: I have constant itching but can't see anything on my skin. How can I find out what is wrong?

Itching can be caused by nerve damage associated with diabetes or lack of vitamin B12, skin diseases, an allergy to something touching the skin or inside your body or a hidden tumor or infection. See my report on neuropathy. Often doctors cannot find the cause.

When more than one person in a family itches, the usually cause is scabies, a disease caused by a parasite that burrows into your skin. You usually cannot see the bug that causes scabies. Sometimes the only way that you can see it is in a piece of skin that has been removed from the body and has been placed under a microscope. You may see little bumps between your fingers, in your armpits and groin, at your belt line or on your back or chest. You also may see three or more bumps in a line. The most common treatment is to cover the entire body for 12 hours with a prescription cream containing permethrin. If you still have itching, your doctor may prescribe a single pill called Ivermectin. Check with your doctor.


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Artichoke-Chickpea Soup

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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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