[Fazc]

I doubt it has anything to do with the upper back. I only really do this just to show that wearing straps has nothing to do with it.

Edit - And for the lulz

When the grip starts to go or is under strain, like it would have been with Donnie's grip work, the upper back starts to round mid-lift. But an intentionally rounded upper back, staying in the same position throughout, is a different beast.

It's like the upper back rounding during a pull, if it rounds progressively more during the lift it's dangerous. If it starts rounded and straightens out, it's probably ok.