Increased blood volume and red blood cell mass
Increased skeletal muscle capillary density, mitochondrial mass, and oxidative capacity
Increased left ventricular mass, end-diastolic dimension, and stroke volume
Increased diameter of coronary arteries
Decrease in resting heart rate
Likely increase in ventricular fibrillation threshold
Explain the different cardiovascular responses to volume overload and pressure overload.
Exercise is commonly characterized as being either endurance or strength-promoting. Most activities have some component of each. At the two extremes are pure endurance training as exemplified by long-distance running, and strength training as exemplified by weight-lifting. These two forms of exercise exert different loads on the cardiovascular system.
The endurance athlete experiences long periods of elevated cardiac output and heart rate, resulting in increased preload. Blood pressure is elevated modestly.
In contrast, the power athlete performs short bursts of intense exercise, with extreme elevations in blood pressure and only small increases in cardiac output. Intra-arterial pressures of 500/200 mmHg have been measured during maximal lifting in elite power athletes. The result is increased afterload.
In afterload stress, septal and free wall thickness increase to normalize myocardial wall stress. Left ventricular cavity dimension does not change. In preload stress, the increase is primarily in ventricular end-diastolic cavity dimension, with a proportional increase in septal and free wall thickness to normalize myocardial wall stress.