Taken from my own lab: using cited information not cited here.
The effects of
aerobic exercise and conditioning are thus:
Aerobic
conditioning is defined as having worked out aerobically for the past 2 months, at least 3-4 times weekly (definition loosely based).
With
conditioning, the
cardiovascular system increases its ability to deliver
oxygen to
muscles, which can also utilize oxygen more easily. This is because with long-term training,
capillary density in muscles increases allowing a greater
extraction of oxygen from blood. Conditioning is also marked with an increase of
capillary density in the muscles, an increase of
mitochondria in muscle cells, and an increase in left
ventricular volume.
Overall, aerobic
exercise increases the body’s cardiovascular endurance and efficiency so that the lungs and heart can, with
less exertion exchange more air and pump more blood, therefore increasing the
efficiency of the system. The pumping
effectiveness of the heart is actually 40 to 50 percent greater in a conditioned person so that the heart can pump more blood with fewer heartbeats. Trained
athletes also have a lower resting heart rate and greater stroke volume.