Alright, here’s some stuff from rock climbing:
They have this thing called a Campus Board. It’s a wall that’s tilted back about ten degrees, so standing in front of it, it’s slightly overhanging. On it are a series of rungs, ranging from an inch in width to about half and inch. so when you hang from a rung, you can only get your fingers on up to the second knuckle on the wide ones, to the first knuckle on the small ones. they’re usually spaced about six inches apart running up the wall, alternating thick/thin. You’d choose the thick ones, hang from the bottom rung, and pullup and slap up two rungs(as in SKIP the next thick rung, yes, grab the one TWO feet up from where you were hanging) then drop down to the one you skipped. that’s the pattern up the wall, up two, down one. or you can jsut sort of jog up and down it, hand over hand. don’t do this without STUPID tendon developement in your fingers.
i used to do laps. but i only weighed 155 at 5’9". and my forearms were nearly the width of my face.
this works good on the underside of a tall step ladder, if being under a ladder doesn’t superstish you out.