Maybe, he meant that if you have a spring mattress, you can take
advantage of the springs recoiling, "Sproing!!" to kinda propel you
back up when doing the sit-up.
I used to 'cheat' when doing sit-ups by doing just that...
i never use spring mattress.
besides oni 20-30 push ups wont really make u pespire.
i just tried it.
still dry.
if sit-ups, i think yeah. my back would be slightly wet.
i don't pespire like a waterfall =.=
