Should the weight be shifted more forwards (towards the points of the feet) or backwards (towards the heels) in pikes/J curls?
I feel that with the weight forwards the stretch is slightly more intense and it is easier to keep legs completely straight. For some reasons however, I feel like backwards is the way to go, and the one which allows a higher degree of folding. Not to mention that you don't risk to lose balance in J-curls.