Cupping is a good tool for Sports Medicine; however, cupping may not be a good idea for an elite athlete prior to an event.
Cupping causes several physiological events to happen. First, the vacuum pressure from the cups pulls in blood and interstitial fluid causing hyperemia (increased blood flow) along with skin stretching and opening of the pores.
Second, the pressure in the small capillary beds for blood within the dermis rupture and hemorrhage to form a hematoma (bruise).
Third, the capillary beds then undergo hemostasis (clotting) to stop the leaking of blood into the interstitial spaces.
Forth, an inflammatory response occurs to remove damaged tissue and mobilize cellular proliferation to the site.
Fifth, tissue repair begins along with angiogenesis (formation of new blood vessels).
Now that you know what cupping does, why would you intentionally break down blood vessels, create inflammation, increase opportunity for fatigue, and compromise the skin’s shielding effect immediately before a world championship competition when winning and losing is measured within a one-thenth of a second?
In my opinion, this specific case of cupping in sports is for a psychological advantage and not a physiological one. If an athlete thinks cupping or Kinesio tape will give them an edge then maybe it will, even if it is just a boost in their confidence.
This confidence may well be nullified by an equal boost in the confidence of competitors by suggesting a weakness or injury.