Cas Long wrote in a different thread:
In my experience, Yonkyo proves more effective on the thinner, more tensile arm , & is more "difficult" to apply on an arm which is thicker.....this is because the technique relies on the compression of the radial nerve which appears closer to the surface of the first type of arm than the latter.
I'd have to disagree with the above. In my opinion, yonkyo is not
a pain compliance technique. In fact, I don't think any
technique in aikido relies on pain but on kuzushi or balance breaking.
Sure, the pain part might be there, but it needn't be nor should it be relied upon. Better in my opinion to treat techniques like nikkyo and yonkyo as balance breaking techniques than pain-producing ones. The pain is just the icing on the proverbial cake in my mind...