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Exercise Won’t Hurt a Healthy Heart

In 1924, famous cardiologist Paul Dudley White claimed that "exercise can’t hurt a healthy heart". Over the years, several poorly-controlled studies have shown that ultra-endurance events, such a running a marathon, might impair heart function. Now a study from Northwestern University shows that Dr. White is still correct (Journal of the American Society of Echocardiography, February 2006). The authors tested 45 patients before they ran the Chicago Marathon and re-tested them one month after the race. They demonstrated that the race had not caused any abnormalities in heart function.

This does not mean that everyone can go out and run a marathon. People who have damaged hearts can die from over- exertion. If you are a middle-aged person who is thinking about starting a vigorous exercise program, you should get a stress test, an electrocardiogram done while you are exercising vigorously. Tests done while a person is at rest often do not pick up blockages in the arteries leading to the heart. If your stress test shows warning signs, you may need further tests. If you pass your stress test, the odds are strong that you can start your exercise program safely. Once you have your doctor's approval, begin your exercise program gradually to build up the strength of your skeletal muscles and your heart over several months. Then you will be ready to start serious training for your marathon or other endurance event.


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Dear Dr. Mirkin: Can dehydration be prevented by drinking sports drinks instead of water?

No. Sports drinks contain a small amount of salt, but not enough to meet your needs. A study in the British Journal of Sports Medicine showed that you cannot replace salt lost through exercise exclusively by taking salty fluids (April 2006). If you are exercising for a long time in warm weather, you need to replace fluid, salt and calories. Salty drinks taste awful, so none of the popular sports drinks contain much salt. You need to eat salty foods along with the beverage of your choice. Since thirst is a very late sign of dehydration and lack of fluids during endurance exercise can kill, all exercisers are encouraged never to wait for thirst to tell them when to drink. By the time an athlete becomes thirsty during a competition, it is too late to drink enough to replenish the fluid loss without stopping to rest.

Many people fear hyponatremia (collapse or even death from too much water during exercise), but sports drinks offer no advantage over any other beverage. Hyponatremia is caused by excess fluid from any source, not by lack of salt or calories. During intense competition, athletes concentrate so hard on maintaining their pace that they are unlikely to take in too much fluid. However, novice athletes often run so slowly that they spend more time drinking than pushing the pace. How much fluid should you drink? The American College of Sports Medicine recommends about a quart an hour during vigorous exercise. For a person who is not exercising near his maximum, this could be too much. The person who is exhausted and exercising significantly below his capacity probably should take in only about a pint per hour.


Dear Dr. Mirkin: Will the nonsteroidal pain medicines help me recover from a workout?

Lots of athletes and exercisers take ibuprofen, an over- the-counter medication, and other nonsteroidals to ease pain in their joints and muscles. A study from the University of Florida (Medicine and Science in Sports and Exercise, May 2006) shows that nonsteroidal drugs inhibit exercise-induced muscle growth and strength.

Athletes train by taking a hard workout and damaging their muscles. They feel sore on the next day and exercise at reduced intensity until their muscles are healed. When they feel no soreness, they take a hard workout again. When muscles heal from the stress of a hard workout, they are larger and stronger. Damaged muscles release a healing prostaglandin called Cox-2, that causes muscle growth and increased strength. Ibuprofen blocks Cox-2 and therefore will delay or inhibit muscle growth. Pain medicines may make you feel better, but at the cost of interfering with the strength gains you are working to achieve.


Favorite Recipes

Clementines are back in the stores (the little citrus packed in boxes or mesh bags). Growers have figured out how to make them available 12 months a year, so enjoy! Eat them right out of the box, or add to your favorite salad.

Clementine-Wild Rice Salad
Clementine-Black Bean Salad
Clementine-Quinoa Salad

You'll find 100 recipes, and lots of helpful diet tips, in The Good Food Book - it's FREE

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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