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Cross-transference Helps If You Are Injured

Most athletes are so afraid to lose conditioning that they get very frustrated when they are injured. They can maintain fitness by using a training technique called cross-transference, and so can you. It surprises most people to hear that exercising one leg or arm helps to maintain strength, endurance and power in the other limb. A review of 16 well-controlled scientific studies shows that strength training of the opposite limb strengthens the inactive muscles by about eight percent, equal to about half the increase in strength of the trained side (Journal of Applied Physiology, November, 2006).

We think that cross-transference acts on the brain to strengthen nerves, rather than muscles. 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, so you can lift heavier weights.

Earlier studies have shown that lowering weights with one arm strengthens the other arm even more than raising a weight. We know that you become stronger by exercising against greater resistance and the heavier the weight that you lift, the greater the gain is strength. A person can lower a heavier weight than he can lift when gravity works with him. Exercising one arm makes the other stronger by teaching the brain to coordinate the muscles in the other arm, and the heavier the weight that you lift with one arm, the more strength you will gain in the other.


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Dear Dr. Mirkin: Does it really matter if my children are slightly overweight?

Researchers at Harvard Medical School found that being even a little bit overweight at age 18 increases chances of dying prematurely (Annals of Internal Medicine, July 2006). This study analyzed data from 102,400 women enrolled in the Nurses' Health Study II. The study author writes: "Prevention of excessive weight gain in those who are not yet overweight may be the most cost- effective approach."

If your children are overweight, you should act now. Telling a child to exercise more and eat less is not effective; you need to set an example. Children with parents who exercise regularly are more likely to exercise themselves. Going on long hikes, taking your child with you to the tennis courts and jogging or cycling together will expose them to regular exercise. Enrolling them in group activities such as tennis lessons, swim team, a weightlifting program or youth leagues in any sport gives a structured activity that can enhance their social life as well.

Keep junk foods that are loaded with fats and sugar out of your house. Sugared drinks do not fill you up as much as the same number of calories in solid foods, so fruit juices and sugared soft drinks cause people to take in more calories than they need. Everyone in your household will benefit from a diet that is rich in fruits, vegetables, whole grains, beans, nuts and other seeds.


Dear Dr. Mirkin: Why do you recommend adding salt when everyone else tells us to stay away from it?

Salt can be both harmful and helpful. Too much salt can cause high blood pressure, clotting, heart attacks and strokes, but lack of salt can cause muscle weakness, fatigue, and headaches and it even can raise blood pressure, cholesterol, insulin and blood sugar. Concern about salt comes from the fact that most people get far too much in packaged foods, animal products, fried foods and preserved foods, and they lose very little because they seldom exercise. However, many health conscious people are at risk for low-salt syndrome when they follow a plant-based diet that contains very little salt and then lose salt through sweat when they exercise.

A recent study from the University of Minnesota showed that regular exercise prevented high blood pressure in salt- sensitive people who were placed on a high-salt diet (Journal of Human Hypertension, May 2006). I know this is true for me. I eat a mostly vegetarian diet with seafood, exercise one to five hours a day, and add a lot of table salt to my food. My blood pressure is 100/50. In the old days when I ate a lot of meat and prepared foods, my blood pressure was 160/110. I take no medication. More


Recipe of the Week

Asparagus-Shrimp Salad

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

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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