Jimmy M. said:If I were to offer either of these as advice, I'd probably say 90° just because I think it's an easy visual. However, I'm not sure how this differs from your hand being directly under your elbow. If your forearm hung straight down at 90°, wouldn't your hand be right under your elbow? Your hand is at the end of your forearm so, if your forearm is hanging straight down from your elbow, then your hand, being at the end of your forearm, would have to be beneath your elbow, right? Sure, you could argue that the elbow joint is, technically, directly above your pinky-finger knuckle if your arm were at an exact 90° angle but, for one, that knuckle is still part of your hand and, secondly, which is the main point I'm trying to make here, it doesn't have to be exact down to the millimeter. Either advice is a guideline; something to give you a mental image while you're down on the ball since, after all, you can't see if your arm is 90° or if your hand is directly under your elbow while you're down on the ball anyway. It's just an image to keep in your head to help achieve your goal, if that's what it is that you're working on.
idk. i always thought of the 90 as your forearm and biceips. if i do that then my hand is not perpendicular with the floor (or under my elbow). to me these are 2 different things.