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EXERCISE CAN'T HURT A HEALTHY HEART
If you're afraid that exercise will hurt your heart, check with your doctor. 70 years ago, Paul Dudley White said "Exercise can't hurt a healthy heart," and no one has proved him wrong yet.
You become tired during exercise because your muscles feel tired. There are two reasons for muscle fatigue: Lack of fuel and lack of oxygen. Skeletal muscles use both fat and sugar for energy. When skeletal muscles run out of their stored sugar called glycogen, they can't contract and function adequately. They hurt and you will find it difficult to coordinate them.
A healthy heart will not tire you during exercise and can withstand all the exercise you can give it. Unlike skeletal muscles that can run out of fuel, your heart muscle can never run out of fuel because it uses fat and sugar carried in your bloodstream and a breakdown product of metabolism called lactic acid. Your heart cannot run out of oxygen unless the arteries that carry blood to your heart are blocked by plaques. Then your heart can hurt from lack of oxygen. So, the only way that your heart can hurt when you exercise is when it is damaged, and that usually means blocked arteries. If you develop chest pain during exercise, something is wrong and you should check with a doctor immediately.
Checked 8/31/05