Runners 'hit the wall' when tissue is damaged


August 10, 1993|By Gabe Mirkin, M.D. | Gabe Mirkin, M.D.,United Feature Syndicate

Between the 18th and 25th mile of a marathon, runners often "hit the wall." Their legs start to stiffen and hurt, and they find it very difficult to finish the race.

The old theory was that a runner "hits the wall" when his leg muscles run out of stored muscle sugar, called glycogen. Muscles store glycogen inside of their cells. During exercise, glycogen is used for energy. When leg muscles run out of their stored glycogen, the muscles hurt and feel stiff.

Tim Noakes, a researcher at the University of Cape Town in South Africa, found that bicycle racers do not "hit the wall" when they use up their muscle glycogen. A bicycle racer's muscles are used to pedaling in a smooth rotary motion that is far less damaging to muscle tissue than is the force of the heel striking the ground during running.

The feet of runners hit the ground with a force greater than three times body weight, causing the leg muscles to be stretched and torn. If you try to run with your hands on the large muscles in the front of your upper legs, you will feel the muscles shake immediately after your heel strikes the ground.

"Hitting the wall" is caused by damage to the fibrous connective tissue that surrounds muscles, which makes muscles feel stiff and heavy. Runners can prevent this by doing eccentric training, such as running rapidly downhill once a week or running very fast interval workouts twice a week.

Just running long distances will not strengthen the leg muscles sufficiently to protect them from "hitting the wall."

Q: Are there any drugs that will help me lose weight safely? -- P.L., Boise, Idaho

A: Some recent papers have shown that drugs may indeed help overweight people lose fat and keep it off. These drugs also seem to be much safer than scientists had previously thought.

Doctors are concerned that most drugs that suppress appetite lose their effect over time, so people have to keep increasing their dose until they reach levels that can harm them.

However, several recent papers have shown that some people can keep on taking the same doses of these stimulants over many years and not start to gain weight until they stop taking their medication.

These drugs affect neurotransmitters, chemicals that carry messages from one nerve to another. They control how you think, feel, move your muscles and just about everything that you do. One neurotransmitter, serotonin, helps to make you feel full when you eat. Another called dopamine helps to suppress appetite.

Pietr Hitzig, a Baltimore physician, feels that the combination of drugs that raises brain levels of serotonin and dopamine may indeed help people lose weight and keep it off.

Recommended doses are: fenfluramine (Pondimin), 10 milligrams twice a day; and phentermine (Adipex, Fastin) 30 milligrams once a day.

If a patient does not lose weight on these low doses, he is given higher doses. The same regimen is used to treat alcohol and cocaine addictions.

I recommend checking with your doctor before using these drugs. I believe this drug combination may help some people lose weight, if they do not have a medical problem that may be aggravated by these drugs, and if they make a permanent change of lifestyle that includes a low-fat diet and exercise.

Q: Is there any treatment for acne that really works? -- V.G., Dunkirk, N.Y.

A: Acne used to cause terrible facial scars, but now dermatologists are able to treat it effectively.

Both men and women have male hormones, which increase oil production. Normally, oil is a colorless liquid, but when it can't get through to the skin's surface, it is converted to a solid white material called sebum, which causes the body to mount an immune reaction of swelling and redness.

Some women's bodies produce excessive amounts of male hormones. They usually have excessive body hair as well as acne and can be treated with drugs to block male hormones.

For the last 45 years, doctors have used antibiotics to block the conversion of liquid to solid oil, but its effect is only temporary so patients often have to stay on antibiotics for years.

The most effective treatment for acne is Accutane, which markedly reduces oil production. Given in doses of around 160 milligrams (four pills) per day for about three months, it can clear up severe acne and keep it clear long after the medication is stopped. However, it can cause muscle aches and very dry skin. Blood tests to check liver functions and blood fat levels have to be done each month, and women must be extraordinarily careful that they do not become pregnant while they are on it as it can cause serious birth defects. There is no evidence that it causes any damage after a woman stops taking it.

Dr. Mirkin is a practicing physician in Silver Spring specializing in sports medicine and nutrition.

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