We saw Michael Phelps take home his 19th Olympic gold medal for the 4×100-meter freestyle relay. We also didn’t miss the massive pigmented circles covering the swimmer’s right shoulder. What exactly are these bruises? They’re evidence of cupping, an ancient Chinese therapy used to stimulate blood flow. Cupping is an ancient Eastern medicine practice that’s used to treat all sorts of ailments, from muscle soreness to blood diseases and arthritis.
Cupping involves cups and the air pressure within them to physically pull the muscles, skin, and blood up. This penetrates the skin up to a few inches beneath the surface for therapeutic effects. There isn’t much science though to support the effects beyond anecdotal evidence, which could be a result of the placebo effect.
How exactly does cupping work? Practitioners first clean a glass cup with alcohol, light a fire in the cup, then place the cup with the opening down onto the skin to extinguish the flame. As the air inside the cup cools, its molecules contract, creating suction that pulls the skin up into the cup. Cupping can also be performed using plastic cups and a manual air pump, no flame required.
How can athletes benefit from cupping? In theory, cupping can bring blood flow to the area to loosen muscles and increase your range of motion to help an individual perform better. There are some studies pointing to mild benefit in terms of reduction of soreness, increased mobility, and less stiffness. According to some researchers, it may make athletes feel better subjectively, but there is no solid evidence to support cupping as a method to enhance recovery from a pure physiological standpoint.
In Phelps’s case, he received it on the traps and deltoids on his right side, so it’s possible he was just trying to iron out any kinks and increase the flexibility in what could be his weaker side or, perhaps, a sore spot.