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Exercise May Improve Kidney Function

We already know that exercise helps to prevent heart attacks, strokes, diabetes, obesity and certain cancers, and may extend life span. Now a report from Italy shows that exercise may also help to prevent kidney damage that occurs with aging (Clinical Journal of Sport Medicine, May 2008).

Doctors measure kidney function by calculating the ability of the kidneys to rid the body of a breakdown product of metabolism called creatinine. Regular exercisers have lower blood creatinine levels and also have kidneys that are better able to clear creatinine from the bloodstream as measured by a test called Glomerular Filtration Rate (GFR).

According to this study, professional bicycle racers have better kidney function than both sedentary people and recreational cyclists. This is very interesting because professional cyclists dehydrate themselves with almost every workout, in spite of the huge amount of fluid they consume. The researchers found that frequent dehydration accompanied by drinking large amounts of water did not cause kidney damage. This repeated stress on the kidneys may even explain why the professional cyclists had better kidney function than the less-active participants.


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Dear Dr. Mirkin: Do toe clips save energy when I bicycle?

For years we have heard that all bicycle riders should have their feet attached to their pedals either with cleats or toe clips, because this helps them to pedal both up and down and therefore use less energy and pedal more efficiently. Recently, researchers at the University of Bath in England showed that cycling efficiency is not altered with and without toe clips (Journal of Sports Sciences, January 2008). The authors wanted to test a claim from one manufacturer that toe clips lower submaximal oxygen consumption (VO2) by 8-18 percent. They showed that it does not.

Almost all serious cyclists today use toe cleats on their shoes that clip onto matching pedals. They do this to get better control so they do not slip off the pedals when they accelerate or make sudden changes in speed. However, now we know that cleats do not decrease their oxygen requirements.


Dear Dr. Mirkin: Does exercise affect breast cancer risk?

A recent study from Washington University School of Medicine in St. Louis shows that exercise starting during adolescence can protect girls from breast cancer (Journal of the National Cancer Institute, May 2008). Researchers tracked 65,000 nurses who answered questionnaires about exercise. Within six years, 550 were diagnosed with breast cancer before menopause. Those who exercised regularly as teens were 23 percent less likely to develop premenopausal breast cancer than their sedentary peers. Ages 12 to 22 appear to be the most important time to use exercise to help prevent breast cancer.

Higher estrogen levels increase risk of breast cancer. Exercise lowers estrogen by reducing body fat. Fat cells make estrogen, and after the menopause fat cells are the principal source of estrogen. Other factors that increase breast cancer risk are also related to higher estrogen levels: starting to menstruate at an early age, late onset of menopause, taking estrogen after menopause, and being overweight.


Recipe of the Week

Savoy Cabbage with Lentils

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

June 25th, 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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