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Cross-Transference Keeps You Strong While Injuries Heal

Injuries upset athletes because they know their competitors are still training. They can maintain fitness by using a training technique called cross transference, and so can you. Exercising one leg or arm helps to maintain strength, endurance and power in the opposite limb. The muscles in the injured limb are not strengthened directly because they are not being used. Cross transference stimulates nerves in both limbs, even though only one is being exercised (Journal of Applied Physiology, November 2005).

Each muscle is made of millions of fibers, and each fiber is stimulated by a single nerve. When you exercise, your brain sends messages along these nerves, telling only about five percent of the nerves to contract at the same time. With training, your brain learns to contract a greater percentage of muscle fibers simultaneously. The more you practice a specific exercise, the greater percentage of your muscle fibers you can contract at the same time. When you stop exercising, your brain quickly loses its ability to contract as many fibers at the same time and you lose strength, endurance and coordination. However, if you continue to exercise one arm, your brain retains its ability to contract the fibers in the opposite arm.

This concept applies only to opposite limbs; you can maintain strength in an injured arm by continuing to exercise the uninjured one, but exercising your legs will not strengthen your arms and vice versa. So if you are a runner who injures a leg muscle, you can work the uninjured leg on resistance machines to keep up the strength of both legs. If you are a baseball pitcher, you can help to maintain strength in an injured arm by using your other arm to throw and do resistance exercises.


Dear Dr. Mirkin: Should we change our diets based on the news that low-fat diets don’t reduce cancers or heart attacks?

You should not be surprised by the latest three studies showing that low-fat diets do not prevent breast and colon cancers and heart attacks (Journal of the American Medical Association, February 8, 2006). These studies were designed several years ago when a lot of people believed that all fats were bad. They did not test the newer diets such as the Mediterranean diet, which recommend eating good fats and avoiding the bad ones. You should restrict the bad saturated and partially hydrogenated fats, not the good omega-3 and monounsaturated fats. Even if you restrict the bad fats, your diet will be unhealthful unless you also restrict the bad refined carbohydrates and eat lots of the good carbohydrates found in fruits, vegetables, whole grains and beans.

The main reason that these studies failed to show protection from cancer and heart attacks was that the women on the low-fat diets did not lose weight. That means that they did not eat fewer calories, even though they were instructed to avoid the most concentrated sources of calories. Heart attacks and cancers are associated with excess weight, and many scientists feel that inflammation explains the link. When germs get into your body, your immunity calls out cells and proteins to kill them. However, if your immunity remains active, it attacks and damages your own body to increase risk for heart attacks, strokes and cancers. We now know that full fat cells (as well as lymph nodes) produce the proteins of immunity to cause inflammation. Here's the diet I recommend to all my patients.


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Dear Dr. Mirkin: Why can’t older men and women compete as effectively as when they were younger?

The faster your heart can beat, the more oxygen-filled blood it can pump to your muscles and the longer and faster you can exercise. A 19-year-old woman with a heart transplant was not able to exercise at all. After she received a pacemaker that sped up her heart rate, she was able to win five gold medals at the European Heart and Lung Transplant Games (Journal of Heart & Lung Transplantation, August 2005).

As you age, your maximum heart rate slows down. The fastest your heart can beat is supposed to be 220 minus your age. When your leg muscles contract, they squeeze veins near them to push blood toward your heart. When you leg muscles relax, the veins fill with blood. Intense training that strengthens leg muscles can increase maximum heart rate so you will still be able to compete against younger athletes. More on maximum heart rate


Recipe of the Week
From reader Suzanne Stapler, a delicious variation on our oatmeal bars:

Suzanne’s Oatmeal Bars

If you have a recipe to share, please send it to

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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