prone jackknifes are no problem, how to challenge it?
Hi everybody, I just started to do NROL4W and "accidently" did 2x15 prone jackknifes in A1, instead of 2x8. It was hard, but I could finish it. So far it's great, but I want to challenge myself, therefore the question: what can I do to increase intensity? Do it with only one leg? I'm looking forward to your ideas! Thanks!
