no no actually, I've passed that phase during the excercise itself, the problem is I feel something "in" my middle spine when I bend over to grab something or tie my shoes etc... it feels akward, it's like... like when you bend a wooden stick, it breaks and gets much more loosen so you can bend it to the other direction, right?
But when you bend it to the opposite direction after that it will break.. that's how my back feels now...
It doesn't hurt... it just feels if I put any presure to it it may snap... it doesn't hurt at all but... doesn't feel right

There must be some getbiger who has lots of experience... by the way,
71 year old doing over 100 reps

... it's on knees but still..