Regular exercise can reduce your blood cholesterol levels, but what happens if you stop working out?
When Dr. Gustav Schonfeld of Washington University in St. Louis asked several regular runners to stop running for several weeks, he found their blood cholesterol levels rose significantly after they stopped exercising.
When you stop exercising for just a couple of weeks, your blood level of cholesterol will return to its previous state. Then you will have to work even harder to control your cholesterol level by restricting fat even more or by beginning to take medicine.
If you have high blood cholesterol levels, you should start a low-fat diet. Diet is more effective than exercise in reducing cholesterol anyway. You should also start a controlled exercise program. If your combined diet and exercise does not reduce your cholesterol, you may need to take medication.
Q. Last week, while I was running to catch a plane, I felt a pain in my chest. I exercise regularly and have never felt anything like it, even when I work out very strenuously. What happened?
A. This pain is sometimes known as "airport angina" and is caused by a partial obstruction of blood flow through the vessels that carry blood to the heart.
The blood that is pumped inside your heart does not nourish the muscle. The oxygen your heart needs comes from blood vessels on its surface. As long as your heart muscle can get all the oxygen it needs, it should not hurt.
Even if the blood vessels on the heart's surface are partially blocked, the heart may still get enough oxygen when you engage in your normal activities. However, when your heart is forced to work overtime, it may not get enough oxygen and could begin to hurt.
When you walk while carrying a heavy weight, such as a suitcase, your arm muscles stay contracted, partially blocking the flow of blood. Your heart must work harder to pump against this increased resistance. The narrowed arteries may not allow enough blood to flow through, and your heart will not get the extra oxygen it needs. As a result, you may develop airport angina.
If you feel chest pain when you exert yourself, whether exercising in the gym or running for a plane, check with your doctor. You probably need a thorough evaluation.
Q. My sister won't exercise because she says it will cause osteoporosis. I thought it was just the opposite -- that exercise could help prevent that problem. Which one of us is right?
A. You are. Exercise cannot cause osteoporosis.
Reports of several recent studies have associated hard and protracted exercise -- such as marathon running, ballet and gymnastics -- with irregular menstrual periods, which cause women's bodies to stop making estrogen. Their bones become smaller and weaker and more likely to break. This is osteoporosis.
But the exercise itself does not cause the irregular periods. The usual cause is not eating enough food. Think about the near-starvation look of some ballerinas and gymnasts. When these women increase their intake of food and continue to exercise, their periods often become regular again.
These studies clearly do not show that exercise causes osteoporosis. Rather, they show that estrogen is necessary to keep bones strong. When a women's body stops making estrogen for any reason -- menopause, illness or an inadequate intake of food -- her bones start to lose calcium at an alarming rate.
Women who lack estrogen and do not exercise lose calcium from their bones at a much faster rate than those who lack estrogen but do exercise. Women who lack estrogen should take estrogen replacement, or another medication called etidronate, to keep their bones from weakening. They also need to take in the amount of calcium equal to that found in five glasses of milk each day, and they should exercise by lifting weights or pushing on special strength-training machines.
Dr. Mirkin is a practicing physician in Silver Spring specializing in sports medicine and nutrition.