Exercise can produce many physical changes in the heart. According to heart researcher Gerald Dorn, these changes are known as cardiac remodeling, or "athlete's heart." Athlete's heart, according to researchers Booher and Smith, occurs because the heart must increase in mass to supply working muscles with appropriate nutrition. The magnitude of heart adaptation is related to the intensity and duration of exercise. According to Dorn, prolonged endurance activities are most likely to promote an enlarged heart.
Short Term Effects
Booher and Smith report that maximal endurance exercise can result in a four to sixfold increase in cardiac output, a threefold increase in heart rate and a twofold increase in stroke volume. During exercise, an increase in the diameter of veins and capillaries causes enhanced blood flow and oxygen to the muscles. This causes an increase in cardiac output, the amount of blood ejected with each beat of the heart, which is needed to supply the muscles with blood and oxygen. These effects are short term and occur within the first few seconds of exercise.
Long Term Effects
Chronic exercise, Booher and Smith report, results in long-term hypertrophy of the heart, particularly the left ventricle. As the heart becomes accustomed to intense, long-term training, it will adapt to more efficiently provide blood and oxygen to the body. This includes an increase in both the size of the heart and the strength of its walls. A training program of 30 to 60 minutes at 60 to 70 percent of one's maximal oxygen uptake at least three to four times a week is needed to produce a significant training effect, Booher and Smith say.
Gender Differences
Gender differences can influence heart adaptations, Booher and Smith report. On average, females have maximal oxygen consumption levels of about 20 to 30 percent less than males with the same amount of training. Women have smaller absolute cardiac mass and thickness, Booher and Smith report, which is a result of having smaller body size and lean body mass. Relative adaptations based on body size, however, are similar in males and females.
Effects on Performance
According to the National Strength and Conditioning Association, an enlarged heart supplies more blood and oxygen to muscles, increasing maximal oxygen consumption. Maximal oxygen consumption is related to endurance performance, so athletes who train intensely for long periods of time will notice less fatigue, less plateau, improved intensity for longer durations and quicker recovery following exercise.
Therapeutic Applications
In addition to performance benefits, Dorn believes that exercise can prevent heart disease. According to Dorn, exercise's positive influence on heart cavity size, metabolic function and improved vascular diameter and function can assist patients who have had heart attacks or heart failure. Increased blood flow and oxygen throughout the body can limit blockage leading to severe heart conditions.
References
- Hypertension; "The Fuzzy Logic of Physiological Cardiac Hypertrophy"; Gerald W. Dorn, II; March, 2007
- Clinics in Sports Medicine; "Physiological Effects of Exercise on the Cardiopulmonary System"; Mark A. Booher and Bryan W. Smith; 2003
- "Essentials of Strength Training and Conditioning"; Thomas R. Baechle and Roger W. Earle (eds.); 2008
