Anyone who saw Michael Phelps' performances at the Rio games saw a perfect example of a dangerous double play proving that just because you are great at something doesn't mean you aren't a moron.
Phelps was displaying the remnants of cupping marks on his back. Having known cupping is utter nonsense for some time I was horrified when I witnessed his blood blistered back knowing full well the repercussions would be a new surge in cupping treatments and even worse, coverage by the media, which as expected covered Phelps' cupping treatments and the efficacy as fact.
I started to write an article about cupping and came across this on Science based medicine which hits the nail on the head.
PS Michael Phelps is obviously the greatest pool athlete of all time but it's very doubtful that cupping has anything to with it.