What the experts say
"It increases blood flow, can reduce muscle tension, and allows athletes or patients to feel improvements in their range of motion," physical therapist Marcus Williams, who uses cupping in practice at Ohio State University Medical Center, says. He adds that while cupping lacks clinical evidence, there are basically three theories to explain why athletes and other people seek it as a form of treatment: it increases blood flow to a local area; the tensile force of stretching the skin helps dull pain signals being sent to the brain; and hormones, like endorphins, are released to help heal the area.
The scientific explanation ultimately doesn't matter much to Williams; patients he's treated say it works. "Just from a subjective standpoint... the patient or the athlete will tell you that they feel better, they feel like they have more range of motion, and less pain, and nine times out of 10 that’s an immediate impact."
Plus, since cupping is non-invasive, it's a pretty cheap and inexpensive treatment that allows them to continue training. "Athletes find that the anti-inflammatory response created by cupping allows them to recover faster," adds Dr. Michael Y. Mizhiritsky, a board-certified physiatrist and specialist of physical medicine and rehabilitation at New York Bone and Joint Specialists. "So, in the case of Olympic athletes who are competing several times per day, cupping is used as both a prevention and recovery mechanism."