Chris can i ask u smth,when i do australian pull ups.When retract my shoulder blades and starting to pull i feel smothing like pain in the lower back is it normal?
hmm. Try to visit a doctor or physiotherapist!
Hmmmm, it might be that since your body is on a kind of plank(horizontal position) your lower back may be holding some of your weight. It's not bad but you need to keep that in mind though. But like Chris said, it would be better to go to a doctor or physical therapist.