Exercise helps put off the inevitable.

The speed with which people age is affected significantly by whether or not they continue to be physically active throughout their lives, notes Charles Davie, an instructor in the University of Oklahoma Adult Fitness Program. "With disuse, we allow our bodies to decline both physically and mentally as our years increase. Although we can expect some decline in maximum performance as we age, leading a physically active lifestyle can prolong the diminishment of our youth."

In the aging process, which begins sometime after 25, depending on the individual, the changes in the cardiovascular system are most noteworthy. Aging people begin to experience an increase in systolic blood pressure and a reduction in over-all cardiac output at rest and during exercise. The valves of the heart may begin to deteriorate and heart muscles decrease in size, reducing the ability to pump large amounts of blood.

In addition, unless they decrease their dietary intake or increase their daily exercise, individuals tend to put on weight due to a decrease in their basal metabolic rate. Meanwhile, their bones and muscles weaken and decrease in size. So, the bad news is that growing older inevitably leaves people less healthy, fatter, and weaker, Davie points out.

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