Originally Posted by Donald Lee
Allowing your back to round with heavy weights and relatively moderate reps or light weight and high reps can both induce injury.
I was not trying to talk about air squats used for conditioning purposes.
Except the whole debate is about whether air squat form is, or is not, applicable to weighted squat form. And specifically, whether attempting to eliminate "buttwink" in air squats will overexaggerate the lumbar curve, leading to bad form on weighted squats.
If you don't *do* air squats then the question simply doesn't arise.