Exercise provokes changes in your heart muscle as it gains strength and pumps with greater efficiency. This transition frequently causes an irregular heart rhythm that may feel like a heavy thumping or an occasional flutter in your chest. Often, these symptoms are harmless, but they also could be a warning sign of the onset of heart or vascular disease.
Exercise Impact
Exercise makes your heart pump harder and, over time, this strengthens your heart muscle and lowers your risk of heart disease by as much as 45 percent, according to the University of Maryland Medical Center. In your first six to 12 weeks of regular exercise, your resting pulse may decrease by 5 to 10 percent because your heart pumps more efficiently as it gains strength and it needs fewer contractions to accomplish its task of circulating blood throughout your body.
Premature Beats
Premature beats are a form of irregular heartbeat, or arrhythmia -- a phenomenon that is common among athletes. A premature beat may feel like a fluttering in your chest or a skipped beat that happens as your heart changes rhythm. For example, your heart may produce two beats in rapid succession, followed by a slight pause to bring the beating back into rhythm. Premature beats usually are not dangerous, but they can be a warning sign of heart disease. It is normal for your heart to skip a beat periodically as it adjusts to its new way of pumping blood, but it if you experience a skipped beat more than once every 20 minutes, see your doctor.
Paroxysmal Supraventricular Tachycardia
Paroxysmal supraventricular tachycardia, or PSVT, also is common in athletes. It results from an irregularity in the electrical signals that govern the heart's pumping rhythm. The electrical pulse re-enters the two atria -- the upper chambers of the heart -- and causes extra heartbeats. This makes you feel like your heart suddenly starts beating very fast and then abruptly returns to a slower rhythm. This phenomenon is not dangerous, and it is most common among young people, particularly during vigorous exercise, according to the National Heart, Lung and Blood Institute.
Risk Factors
Certain medical conditions increase your risk of heart attack or stroke when exercising. These include high blood pressure, uncontrolled diabetes, congenital heart defects, a previous heart attack or any condition that provokes seizures. Use of steroids also increases your risk. In many cases, the benefits of exercise outweigh the risks, but you should exercise under medical supervision if you have any of these conditions. Your doctor may advise against intense exercise, such as running or tennis, but she likely will encourage more moderate forms of exercise, such as an elliptical trainer or walking.
Warning Signs
If you feel dizzy or faint, or if you experience shortness of breath or chest pains when exercising, consult your doctor. Simple tests can determine if your heart is healthy or if you need treatment to help prevent serious consequences, such as a heart attack or a stroke. You also could be overtraining and stressing your heart muscle, so your doctor may recommend that you scale back on your exercise a bit. In most cases, treatment for heart disease does not preclude exercising, and your doctor likely will encourage certain forms of exercise to help strengthen your heart.
