Funnily enough, this seems to be common knowledge amongst gym instructors. Yet many of the people who routinely do pushups as part of the conditioning or warmup

Funnily enough, this seems to be common knowledge amongst gym instructors. Yet many of the people who routinely do pushups as part of the conditioning or warmup for indoor sports don't seem to know, even if people have been doing it for decades. Even worse, in the cases that I'm experienced with (for various martial arts) these pushups are done on mats that make it even worse because the wrist is even more over-stretched (because the ball of the hand sinks into the soft mat, while the fingers do so less); and doing push-ups on the knuckles is considered something 'for the hard core'.