Knuckle Hardening

[TAZ]

since i started karate, doing pushups the regular way just doesnt feel right, we also at the end of every class, do knuckle jumps as well

What are knuckle jumps? Could you explain? And why would you do them at the end of class and not at the end of the conditioning exercises?

[cleung]

That's what I use to do too in training for board breaking. It just desensitizes the knuckles. I don't do it anymore since I no longer break boards.