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An occasional jump in your heart rate causes temporary changes in your body, but these changes have little if any long-term hemodynamic effect, a term that refers to how your heart circulates blood. When you exercise on a regular basis for a sustained period, your body responds in several very positive ways. One of the most significant, yet gradual changes are in your heart, with a more efficient hemodynamic response.
Increased Cardiac Efficiency
Regular exercise over an extended period actually causes your heart muscle to enlarge. While the chambers inside your heart essentially remain the same size, the muscle fibers in the walls surrounding these chambers thicken and get stronger. A person who exercises on a regular basis has a much more efficient hemodynamic response creating improved circulation and greater oxygen utilization, than a person who doesn't consistently exercise. This increased efficiency occurs because the heart becomes conditioned to pump a much larger volume of blood during exercise, and it remains efficient at rest as well.
One measure of your heart's efficiency or your hemodynamic status is stroke volume, which is the volume of blood moved by each contraction. The cardiac output is obtained by multiplying the stroke volume by the number of contractions per minute. The harder you exercise, the greater the stroke volume. In response to the increased demands made on your heart during exercise, your faster heartbeat enables your heart to pump more blood per minute.
A healthy resting heart rate is about 60 to 70 beats per minute, with cardiac output reaching up to 9 pints per minute. During aerobic exercise, such as running or jogging for instance, your heart rate can quickly reach 200 beats per minute, which also increases your cardiac output. This consistent hemodynamic response increases the efficiency of your circulation. Individuals in good physical condition tend to have a slower pulse at rest, yet each heart beat forces a greater volume of blood. A professional athlete can have a heart rate as low as 40 beats per minute.
Your hemodynamic response during exercise not only increases the efficiency of your heart and circulation, it also has a positive effect on your muscles. During sustained exercise your muscles frequently and rapidly contract and relax. To do this, your muscle cells need energy to contract, and this energy is gained by burning fats and glucose provided by the bloodstream. When you exercise on a regular basis, your improved hemodynamic status causes several significant changes. A greater volume of blood is channeled through your muscles, and the muscle cells become more efficient at storing and utilizing the energy that the blood provides.