Originally Posted by LT Ice Cream
Well I don't have access to a weight room. I've just been doing a lot of squats, lunges and calf raises with a heavy backpack on. Is this enough, or do I really need to pile on the heavy weights to make significant progress?
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.