Story highlights Increased blood flow helps explain why exercise leads to better sexual function

Those who exercise may be more likely to feel sexually desirable, which can lead to better sex

The following is adapted from "Fitter Faster: The Smart Way to Get in Shape in Just Minutes a Day" by Robert J. Davis with Brad Kolowich Jr.

(CNN) You've likely heard that regular exercise can reduce the risk of chronic conditions such as heart disease, diabetes or osteoporosis.

But a growing body of research shows it may have another, more surprising effect: improving your sex life.

In men, regular exercise appears to be a natural Viagra: It's associated with a lower risk of erectile problems.

In one small study, sedentary middle-aged men assigned to participate in a vigorous exercise program for nine months reported more frequent sexual activity , improved sexual function and greater satisfaction. Those whose fitness levels increased most saw the biggest improvements in their sex lives.

Research in women has found that those who are physically active report greater sexual desire, arousal and satisfaction than women who are sedentary.