Your heart rate is elevated. You’re working up a sweat. Your muscles are tensing up… Your heart rate is elevated. You’re working up a sweat. Your muscles are tensing up like you’re lifting twice your body weight. You don’t think you can go much longer.

And then you get out of bed.

Sex, according to experts, delivers many of the same benefits that more traditional forms of exercise do.

Researchers reported in The American Journal of Cardiology that men who have sex at least twice a week are half as likely to develop heart disease, the top cause of death in the United States.

Meanwhile, Australian researchers said men who have sex frequently when they are in their 20s are less likely to develop prostate cancer later in life.

And ladies, the benefits aren’t just for men. WebMD lists 10 surprising benefits of intercourse, and they include reducing general pain, improving self-esteem, and yes, even aiding insomnia. The website tells women that this benefit is “something to think about, especially if you’ve been wondering why your guy can be active one minute and snoring the next.”

There’s science behind all this. Sex releases endorphins in the brain, which lower pain levels and make you feel good, among other things. If you’ve heard of the runner’s high, this is the same mechanism.

Sex and exercise function similarly in many other ways. If it gets your blood pumping, your body gets a workout — it doesn’t matter if the reason you’re sweating is an early morning jog, afternoon football or late-night alone time with your significant other.

Both sex and traditional exercise cause an “afterglow,” a natural glow of the skin found especially among women. The website GreenOrganics.com also argues that sex clears the pores, lowers stress levels and makes “your hair shine and your skin smooth.”

Other sources agree with the claim that sex operates as a stress reliever. Scottish researchers reported in Biological Psychology that sexually active test subjects responded better to stressors and had lower blood pressure. Another study said that simple hugs work the same way.

With the promulgation of erectile dysfunction drugs, older couples can use sex to stay active in the autumn of their lives. According to a 20-year study by English researchers, intercourse helped abate strokes and cardiovascular problems. While you can’t stay active by means of football and hockey when you hit 70, you can always make love (and swim).

Sex might actually be one of the safer forms of exercise, albeit unorthodox. Major injuries during intercourse are rare — the odd injuries that sprinkle the Web are more sources of humor than serious words of caution.

Common injuries, according to a poll conducted by a British erotic retail chain, include brush burns and muscle pulls. Widespread injuries from jogging look similar: cuts and muscle soreness.

In terms of burning calories, sex ranks among other workouts, though studies struggle to pinpoint an exact number. One pessimistic study said 30 minutes of sex burns at minimum 85 calories, but another study argued sex can burn up to five calories per minute — or 300 per hour.

In the end, it depends on the individual. But Fitness Magazine devotes a section of its website to sexual exercise, or “sexercise.”

Though the exact details — and accompanying diagrams — may be unsuitable for publication, the site details what positions work out what muscles. “The more she does buttock squeezes, the more she could accentuate her riding toward him to give herself a good glute workout,” said Dr. Patti Britton, president of the American association for Sexuality Educators.

It goes on from there.

The ties between sexual pleasure and exercise go beyond the bedroom. Dr. Cindy Meston of the University of Texas at Austin reported that physical exertion beforehand heightens a woman’s sexual experience later. If a romantic candle-lit dinner doesn’t do the trick, try some tennis next time.

ABC’s Dan Childs reported last year that French President Nicolas Sarkozy saw “improved sex” because of “exercise that targets muscles in the pelvic floor.” And the French know love.

Even beyond sexual intercourse, activities like pole dancing and strip aerobics work out the body just like any other exercise.

So it turns out, though it probably isn’t your primary goal, having sex is great for your health — provided you don’t smoke after.