The sight of Olympic swimmer, Michael Phelps, with bruises on his body caused by cupping resulted in something of a media feeding-frenzy this week. He’s a great athlete so cupping must be responsible for his performance, right? Just as cupping must be responsible for the complexion of an earlier enthusiast, Gwyneth Paltrow.

The main thing in common between Phelps and Paltrow is that they both have a great deal of money. Money is something that allows you to indulge any whim, not matter how scientifically unfounded they may be.

The problem with all sports medicine is that tiny effects could make a difference. When three hour endurance events end with a second or less separating the winner from the rest, which is an effect of less than 0.01 per cent. Such tiny effects will never be detectable experimentally.

What is cupping?

That leaves the door open to every charlatan to sell silly 'miracle' treatments that might just work.

And out of all the snake oil techniques I've come across as a pharmacologist and someone whose job it is to debunk pseudoscience, cupping may be one of the silliest.

It’s a prescientific medical practice that started in a time when there was no understanding of physiology. In this way, it’s much like bloodletting – a standard part of medical treatment for hundreds of years, and killed countless people.

At first glance it seems implausible that putting suction cups on your skin would have any benefits – so it’s not surprising that there is no empirical evidence that suggests it does. The Chinese version of cupping is related to acupuncture, which has been very thoroughly tested. Over 3000 trials have failed to show any significant benefit. Acupuncture is no more than a theatrical placebo. And even its placebo effects are too small to be useful.

Cupping: On your marks for ancient treatment Show all 3 1 /3 Cupping: On your marks for ancient treatment Cupping: On your marks for ancient treatment Up for the cups: Chinese swimmer Wang Qun Getty Images Cupping: On your marks for ancient treatment Cupping: On your marks for ancient treatment Rob Sharp tries out the ancient therapy TeriPengilley

Luckily, cupping doesn’t inflict any lasting damage. Although we don’t know for sure because in the world of alternative medicine there is no system for recording negative effects (and there is a vested interest in not reporting them). In extreme cases, it can leave holes in your skin that pose a serious danger of infection, but most people probably end up with just broken capillaries and bruises. Why would anyone want that?

Cupping compared to doping by Russian TV news anchor

Sales people can’t even agree on what the benefits are alleged to be. It’s often claimed that it relieves pain, aids recovery, or increases performance for athletes. Yet no-one can point to any evidence that sucking up bits of skin into jars has any noticeable effect on blood flow in underlying muscles.

Exactly the same cupping methods are sold to celebs with the claim that their beauty will be improved because cupping will “boost your immune system”. This claim is universal in the world of make-believe medicine, when the salespeople can think of nothing else. There is no surer sign of quackery. No procedure is known to boost your immune system. And even if anything did, it would be more likely to cause inflammation and blood clots than to help you run faster or improve your complexion.