WELLINGTON, Fla. -- You may have noticed some strange markings on some Olympic athletes. On Sunday, you could see dark, circular bruises across Michael Phelps' back and shoulders.
The bruises come from "cupping," a technique used to relieve muscle tension and get rid of toxins in your body according to Leanne Mitchell.
Mitchell is the owner of "Acupuncture and Wellness of the Palm Beaches" and is also an acupuncture physician there.
Mitchell uses the traditional form of "cupping" which involves putting a flame inside a glass cup then putting that glass on someone's skin.
She said the fire sucks the oxygen out of the glass and then creates a suction effect on the skin.
"Sometimes we move it around, sometimes we leave it on for about five minutes, sometimes less. It depends on the reaction of the body and the condition that we're treating," Mitchell said.
The darkness of the bruises will vary, she said.
"The more problematic the condition is, the more bruising will occur," Mitchell said.
She said the bruises can last anywhere from two days to a week.
Mitchell typically uses acupuncture along with cupping, and won't do the technique on people with weak immune systems or those prescribed blood thinners.
She said it's useful to people of all ages, and it's not just for athletes.
"A lot of time those stressors are accumulating along the neck or shoulders so we could all use a little bit of cupping," Mitchell said.
Terree Shields has the technique done on her back at least once a month.
Despite the bruises, she said it's not very painful, "It just feels like suction, like a vacuum cleaner hose or something but not even that intense. You feel pressure. A little bit of pressure."
Shields is a yoga instructor and said she sometimes feels pain and tightness in her back.
"I have found a lot of relief from muscle pain and it just helps me feel better. It just relaxes the muscles, it allows for fluid movement. It's really cool," Shields said.