When swimmer Michael Phelps showed up to the 2016 Rio Olympics Games with circular purple bruises on his back, spectators were confused. Numerous online publications shed light on why he had the bruises, revealing that were the result of a recent cupping therapy session. Since then, cupping therapy has become more popular among professional athletes, celebrities, and everyday people.

Cupping therapy is nothing new. It's a healing modality that's been used in traditional Chinese medicine (TCM) for thousands of years, according to Shari Auth, D.A.C.M., L.Ac., L.M.T., certified doctor of acupuncture and Chinese medicine and co-founder of WTHN, a wellness studio in New York. But as with other TCM healing therapies, such as acupuncture or ear seeding, cupping therapy has recently grown in popularity in the Western world. Fans of the treatment (including Jennifer Aniston and Gwyneth Paltrow), swear by its restorative effects on aching pains and sore muscles.

If you're curious about the TCM practice, keep reading to learn more about the treatment, including cupping therapy benefits and how it works.

"Cupping therapy is a healing modality in traditional Chinese medicine that involves the use of cups to create suction on your skin," says Auth. "This suction stimulates circulation to help relieve muscle tension, increase the body's natural detox processes, and alleviate respiratory congestion." (Related: Should You Work Out When You're Sore?)

The cups used in cupping therapy are typically made from glass, but other materials, such as bamboo, animal horns, and shells have been used for thousands of years, explains Gudrun Snyder, D.Ac. M.Sc. L.Ac., a doctor of East Asian acupuncture and founder of Moon Rabbit Acupuncture.

The process begins with your practitioner creating a vacuum on your skin with the cups, explains Auth. Once the cup is on your skin, the natural vacuum draws your skin into the cup. Then the cups are left on your body for anywhere from ten to 45 minutes, according to Auth.

There are many forms of cupping therapy, but two of the most common types are fire cupping and pneumatic cupping, explains Snyder. "For fire cupping, [a practitioner will] place a flame inside glass cups to create a vacuum (aka the suction)," she says. The practitioner lights a match inside the cup before extinguishing the fire and then placing the warm cups on your body.

"For pneumatic cups, [a practitioner will] remove the air from inside the cups to create a suction," says Snyder. Typically, the studios will use plastic cups and a suction gun to remove the air and create the suction, explains Auth. Some studios, including WTHN, will only offer pneumatic cupping for ease and safety, she says.

Cupping therapy can be performed by several types of practitioners including, acupuncturists, chiropractors, massage therapists, medical doctors, and physical therapists, according to the Cleveland Clinic.

Think of cupping therapy as a massage, but without the possibility of pain from too much pressure. "Instead of pressing down, the cups pull up on the muscular fascia," explains Snyder. In case you're unfamiliar, fascia is the connective tissue that surrounds and supports your muscles, bones, tendons, ligaments, organs, nerves. Fascia is able to stretch when you move, but when stressed, it can tighten around muscles, causing limited mobility and painful knots to develop, according to John Hopkins Medicine. Your fascia can become stressed from poor posture, a lifestyle with limited mobility, overworking your body either through working out or repetitive movements, or trauma, such as an injury, reports John Hopkins Medicine. "The cups help reset this fascia and relax it, releasing knots and tightness," says Snyder. A cupping treatment can also stimulate blood circulation, promoting blood flow where the cups are placed, which has a healing effect, says Auth.

One of the pros of this treatment is that you can experience results after just one cupping session. "After cupping, people often report feeling a release of tight muscles and a sense of relaxation," says Snyder. Depending on your concerns, though, you may benefit from regular sessions. "There's no one-size-fits-all cupping routine, [but] your acupuncturist can recommend the frequency required to achieve your health goals," says Auth. "In general, around once per month will keep your muscles feeling great." (Related: CrossFit Athletes Share Their Tips for Dealing with Delayed-Onset Muscle Soreness)

Cupping therapy is loved by active people for its ability to treat sore, achy muscles in all parts of the body, such as the upper back, shoulders, and neck, says Snyder.

In case you're still not sold, some studies show that the benefits go beyond soothing muscular pain. Cupping therapy can promote relaxation and enhance circulation, according to Auth. If you're someone who experiences chronic muscular pain, tension, or stress, you might find the intervention helpful.

It can also help with respiratory issues caused by the common cold. "Cupping [is used] to treat lingering upper respiratory issues such as a phlegmy cough or congestion by increasing the circulation in the upper body and drawing toxins to the surface for easier elimination," says Snyder.

One of the biggest concerns surrounding cupping therapy is the infamous circular bruises that happen afterward. (Insert photo of Michael Phelps circa 2016 here.) However, rest assured that the bruising looks worse than it feels.

"Cupping can result in temporary discoloration of the skin, what we call petechiae," explains Snyder. "These marks are a result of improved blood flow to the area and will dissipate either the day of treatment or up to two weeks [later], depending on the level of injury and underlying health."

Despite how it looks, the marks don't actually feel like a bruise. "These cupping marks do not hurt. In fact, you [won't] even know they [are] there," says Auth. The color of the marks can range from dark purple to light pink, or sometimes no marks at all, she explains. "A darker mark can indicate a higher level of tension, but the cups are still working even if you don't have marks." That said, you might not want to undergo cupping therapy if you have a special event coming up.

Additionally, you might need to avoid cupping therapy altogether if you have any bleeding or blood clotting disorders such as hemophilia, and those with psoriasis or eczema may also find the therapy irritating, according to the Cleveland Clinic. When in doubt, it's best to consult with a doctor if you have any concerns.

Ultimately, though, if you're someone who's experiencing aches, pains, or tension, and feel like you aren't finding relief no matter how much you foam roll, stretch, or soak with Epsom salts, cupping therapy might be just the thing you're looking for.