One of the first documentations of washing a person's mouth out with soap is in a story entitled “Scaramouches at School,” which was published in a periodical in the 1860s.

As recently as the 1940s, it was a common hazing ritual in the British Royal Navy.

In 1996, the American Academy of Pediatrics classified it as an alternative to spanking.

But it's a bad idea in many ways (soap ingredients can make you sick, and it's abusive), and now we know about one more serious drawback: It turns out that killing off bacteria in your oral biome can actually interfere with the positive effects of cardiovascular exercise.

A study of 23 adults published in the journal Free Radical Biology and Medicine found that one hour after exercise, people who had used an antibacterial mouthwash earlier experienced less cardiovascular benefit than those who rinsed with water.

It seems that post-exercise reduction in systolic blood pressure (that's a standard reaction) was about two and a half times less when participants used the mouthwash than when they didn’t.

Why does the antibacterial rinse make a difference?

Because it interferes with the body's post-exercise production of blood-vessel dilating nitric oxide — a process that depends on certain bacteria being alive and well in the mouth and saliva.

If you're concerned with bad breath, make sure you're flossing daily, brushing twice a day or more, seeing a dentist every six to 12 months, and don't smoke.

That's what it takes to have decay-free teeth and good breath, and promote body-wide health.