Extreme cupping therapy - GIF

[Jon]

You can probably dig up a few small cohort studies that demonstrate its efficacy, and a few famous people who swear by it.

There is no known mechanism to support it as a general medical therapy, and good luck trying to separate it from a placebo. You would have to create a viable "fake" cupping method. This is actually what they did with acupuncture studies, using a non-penetrating acupuncture needle so that they could at least single-blind the studies.

Localized stimulation - like how you grab and rub a part of your body immediately after injuring it - has some small positive effect. These pseudomedical treatments combine that, plus difficulty of double blinding, plus placebo effect, and voila: "healing".