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If running, climbing, lifting or cycling doesn’t do it for you when it comes to your daily workout, we have good news. It turns out that breaking a sweat in bed is actually the best exercise you can do. According to new research, sex is the only physical activity that engages every single muscle in your body — giving us another good reason for getting (and staying) busy between the sheets.

There are 657 muscles in every human body (the penis isn’t one of them, in case you were wondering). Upbeat Active, which conducted the study, tallied how many are worked in everyday activities, determining that crying uses 17, texting 38, break-dancing 133 and a golf 137. But sex, if done correctly, actually uses all 657!

Related: The 6 Worst Foods to Eat Before Having Sex and the 5 Best

“We require every muscle to fire on all cylinders. In the bedroom, every muscle matters,” explains leading researcher Mike Aunger, a physiotherapist and muscle anatomy expert, to The Telegraph. “All your skeletal muscles are essential for movement, no matter how vigorous; all your autonomous (involuntary) smooth muscles play a ceaseless role in digestion, respiration, circulation and bodily function; and, of course, your cardiac muscles are integral for pumping blood into all the right places.”

The bulbospongiosus muscle, covering the bulb of the penis in men and the vestibular bulb in women (also known as the “sex hero muscle”) was found by researchers to be the most important muscle for sex. It is responsible for male erections and ejaculations as well as clitoral erections for women and orgasmic contractions for both sexes. The fun part is, the best way to train the bulbospongiosus, as well as all the other sex muscles, is having lots of sex.

Aunger cautions that inactivity is “one of the 10 leading risk factors for global mortality, according to the World Health Organization” and that “insufficient activity” can increase the risk of death by a whopping 20 to 30 percent.

“From birth to around your 30th birthday your muscles are capable of growing bigger and stronger. But once you hit your fourth decade your muscles are on the slide. This can leave you more at risk of injury and less equipped to handle the daily demands of everyday life. It’s never been more important to keep your muscles healthy,” he warns, adding that you can lose 3 to 5 percent of your muscle mass every decade you are physically inactive.

The best way to slow the decline? Regular exercise — including sexcapades — and “optimal protein nutrition.”

Another interesting point is that penis size or position don’t really matter when it comes to the sexual workout: The most important component is the time factor.

“Ideally it should last more than 30 minutes,” he explains, noting, “45 minutes would probably be better.”

While sex is great for working all your muscles, unless your marathons occur multiple times a day for long periods of time, you will probably need to supplement with other workouts. According to a 2013 study from the University of Montreal, women burn an average of 69 calories per romp and men 100, with the average session lasting 25 minutes from start of foreplay to finish.

To read about more of the benefits of sex, click here.

Related: The 6-Week Spring Shred With Anna Victoria

What Do YOU Think?

What are your thoughts on this interesting new study? Will it influence your sex life? Do you have any tricks for burning more calories during sex?