Phelps isn't the only one. Former Olympic swimmer Natalie Coughlin and gymnast Alex Naddour have displayed the distinctive circular welts too.
The New York Times, USA Today, and People all ran articles yesterday explaining what those nasty red bruises were all over Phelps' torso and shoulders. USA Today reported, unquestioningly, that athletes use cupping "to relieve tension in their muscles." The NY Times (from which we might expect a bit more skepticism) reported blithely that "Physiologically, cupping is thought to draw blood to the affected area, reducing soreness and speeding healing of overworked muscles." People used the same argument, and then added this bit of illogic:
"given that Phelps took home his 23rd Olympic medal last night, it's tough to argue."No, it's not. Cupping is ridiculous. There's no scientific or medical evidence that it provides any benefit. The NY Times did express a bit of doubt (though not much), summarizing two small experiments that showed that cupping worked no better than placebo. But the Times couldn't help itself, and went back to quoting anecdotal evidence from true believers.
Rather than review the evidence here, I refer you to a thorough takedown of cupping written last month by Orac, a well-known science blogger who is also a surgeon:
"Among the silliest of alternative medicine therapies is something called cupping.... The suction from cupping breaks capillaries, which is why not infrequently there are bruises left in the shape of the cups afterward."As Orac points out, repeated cupping in the same spot can destroy your skin and lead to dangerous infections. Another physician, Dr. Harriett Hall, in an article for Slate in 2012, made similar points.
I'm not sure who told Michael Phelps that cupping would help him swim faster, but I am sure that it's terrible advice–definitely not helpful and maybe harmful.
I know athletes are notoriously superstitious, and they get some psychological benefits from the various rituals they use to prepare for competition. There's no harm in believing that magic tape, or a lucky shirt, or always stepping onto the field with your left foot first–or whatever–will help you win. But Michael Phelps and his fellow Olympians should run as fast as possible from unproven treatments (and make no mistake, cupping is one of these) that can only cause them harm.