Answer:
In general:
The heart muscle and the general cardiovascular system become more efficient. The exercise also helps the body to build muscle and burn fat. Unless you have arthritis or some other condition which restricts your tolerance to exercise, there are no negative side effects of exercise.
Short term effects:
Anticipatory heart rate, Heart rate at onset of exercise, Redirection of blood flow, Vasodilation, Vasconstruction.
Long term effects:
Cardiac hypertrophy, Increased stroke volume, Increased cardiac output, Decreased resting heart rate.
More information:
For additional information about the benefits of cardio (cardiovascular) exercise, see the page link, further down this page, listed under Related Questions.
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