The heart is the strongest muscle in the human body. Hardwired to beat automatically, the heart is a sophisticated combination of muscles and nerves that control and modulate your heart rate. According to the Yale University School of Medicine, the heart beats more than 100,000 times per day and circulates 2,000 gallons of blood that is distributed over 60,000 miles of blood vessels. The less sturdy aging heart is vulnerable to problems such as rhythm disturbances aggravated by exercise.
The Aging Heart
Diseases such as hypertension and coronary heart disease are more prevalent in people older than 70 years of age, with the latter condition being the major cause of death in the elderly population. Physiologically, the muscles of the aged heart relax less in between beats. Wall motion of the ventricles is stiff making the pumping action of the heart less efficient. The heart's conduction system, which is responsible for the initiation and conduction of electrical stimulus that cause the muscles of the heart to contract, also shows evidence of wear that manifests as disturbances of cardiac rhythm that can be felt during and after exercise.
Effects of Exercise on the Heart
The heart's electrical conduction system responds to the increase in adrenalin that occurs during exercise. Adrenalin causes the heart rate and blood pressure to increase. Likewise, there is an increases in the vascular resistance of arteries. Heart conditions such as plaque in the coronary arteries can compromise the delivery of additional oxygen required by the heart during exercise, which favors arrhythmia. The adrenalin released during exercise can be a potent stimulus for arrhythmia, especially if the heart has underlying structural problems.
Rhythm Disturbances
The heart's electrical conduction system that controls your heart beat is arranged in a circuitous pattern within the atria and ventricles of the heart. The initial impulse for the heart to beat normally originates from an area at the beginning of the circuit called the sinus or SA node. The impulse then spreads serially along the conduction pathway from the atria to the ventricles. A breakdown along this pathway can result in arrhythmia. The type of arrhythmia that occurs depends upon where in the electrical pathway the breakdown has occurred. Adrenaline exerts a pro-arrhythmic stress on a diseased heart.
Atrial Fibrillation
A small percentage of the elderly population have a rapid arrhythmia called atrial fibrillation or a-fib. A-fib occurs when the heart's conduction system receives many stimuli from the atria. The most common cause for a-fib is hypertension but other conditions such as cardiomyopathy, coronary artery disease and valvular heart disease can be associated with it as well. Dizziness, fainting, stroke and shortness of breath are some of the symptoms of a-fib.
Exercise and caffeine are potent triggers of a-fib, and people with this arrhythmia often complain of irregular heartbeats during and after exercise. According to Dr. Brian Olshansky, a-fib is more common in men, but women are more likely to feel and be aware of the arrhythmia. People with a-fib should not start an exercise program without first consulting a health-care practitioner. An irregular heart beat requires an EKG for diagnosis to rule out a-fib or other arrhythmia. If you have irregular heartbeats after exercise, promptly seek the advice of your health-care provider.
