Moderate exercise decreases the risk for sudden heart attack. However, strenuous physical activity increases risk for heart failure for people with coronary heart disease. The coronary arteries supply oxygen in the blood to all cells in the heart. When an artery is partially blocked, blood supply slows or stops, and the muscle tissue begins to die causing heart failure.
Coronary Heart Disease
In coronary heart disease, the arteries may become narrow or close up and reduce or stop blood flow to your heart. The most frequent cause is fatty deposits building up on the inner walls of arteries. Without an adequate blood supply, your heart muscle cannot function properly and may beat more shallowly and not pump enough blood throughout your body.
Warning Signs
Be aware of unusual symptoms while exercising, shoveling snow or performing physically demanding tasks. Seek immediate medical attention for pain or uncomfortable pressure in the center of the chest lasting more than a few minutes. uncomfortable pressure, fullness or squeezing or pain in the center of the chest that lasts more than a few minutes or that spreads to the shoulders, neck or arms. Additional symptoms accompanying the pain may include nausea, sweating, difficulty breathing, feeling lightheaded or fainting, according to the American Heart Association's ""Guide to Heart Attack Treatment Recovery and Prevention."
Risk Factors
Age and having family members with heart disease are risk factors for heart attack that cannot be changed. Lifestyle changes may protect against heart attack, including quitting smoking, reducing cholesterol and controlling high blood pressure. Moderate aerobic exercise, like walking or swimming, strengthens your heart.
Rhythm Disturbances
An electrical pulse controls the heart's pumping action. In the April 9, 2004, issue of "Science," researchers at Columbia University College of Physicians and Surgeons reported that a protein called calstabin2 attaches to a receptor during the relaxation phase of the heartbeat in mice. This binding prevents a leakage of calcium through the channel that causes the electrical pulse. In mice unable to produce enough of the protein, strenuous exercise caused rhythm disturbances leading to death. The authors pointed out that individuals with a mutation of the receptorare at risk of exercise-induced arrhythmia and sudden cardiac death.
Shortness of Breath
Loss of breath during exercise occurs frequently in people with chronic heart failure. According to a study published in the July 1999 issue of "Chest," potassium stimulates breathing during exercise, and potassium levels increase from the release of potassium from skeletal muscles. Participants in the study with chronic heart failure developed decreased potassium levels circulating in the blood during exercise, leading to decreased aerobic capacity and breathlessness.
Diastolic Dysfunction
During the period between heartbeats, called diastole, the heart relaxes. In the November 2, 2005, issue of "Chest," researchers at Seton Hall University reported that 47 percent of participants with shortness of breath developed exercise-induced diastolic dysfunction without evidence of less oxygen being available to the heart. In this study of 32 patients, more females and patients with high blood pressure developed exercise-induced diastolic abnormalities.
References
- "Guide to Heart Attack Treatment Recovery and Prevention"; American Heart Association; 1996
- "Science"; Protection from Cardiac Arrhythmia Through Ryanodine Receptor-Stabilizing Protein; Xander HT Wherens et al; April 9, 2004
- "Chest"; Exercise-Induced Rise in Arterial Potassium in Patients With Chronic Heart Failure; Yasuhiko Tanabe et al; July 1999
- "Chest"; Exercise Induced Diastolic Dysfunction; VK Mithani MD et al; Nov. 2, 2005
