Originally Posted by plowking
If there is one thing worse than ankle weights, I'd have to say its what you're doing at the moment. You never want a dragging weight on your back like a heavy backpack. Especially while doing explosive movements. Its going to play with your back.
If you were to do it with a backpack, you'd also want one at the front of equal weight, as stupid as it will look.
You're better off just getting a set of dumbells, about 22-25lbs and holding them while jumping. Jumping with 45lbs in your hands will help a lot.
Thanks for catching me b4 I messed myself up