Bent Hollow Body

Hello! I was wondering how my son's bent hollow body looks. He has just come back after months of being injured and doing PT, and is very weak now. Does he have the flat back syndrome or any other major problem? 

Thanks! 

I know it looks like he is squirming a lot, but he is trying to breathe while flexing his core. Any tips on how to continue breathing and minimize movement at the same time?

I would say compared to the instruction video try to get his feet closer to the ground, as that is harder begin with shorter holding times.

Breathing is ok.

Arms should be moved closer to the ground. be sure that the scapula region is moved off from the ground.

Thanks! He actually finds arms closer to the ground easier, but he'll try this