This has reminded me of the Melzack & Wall gate theory of pain control..... is an interesting topic to read about.... and explains.why rubbing a bruised area brings relief to many. Acupressure may be explained by this.

https://www.verywellmind.com/what-is-gate-control-theory-2795208

https://www.sciencedirect.com/topics/medicine-and-dentistry/gate-control-theory#:~:text=The%20gate%2Dcontrol%20theory%20(Melzack,delta%20and%20C%2D)%20fibres.