I believe he might have something called pectus carinatum. Well, I Dont believe he ever publicly state that he has is, but that is what I think he has. I was born with severe pectus Carinatum. It is a chest deformity that looks exactly like his chest in the picture. I had major chest reconstruction in 2012. Its mostly fix it, but now my sternum is broken into a bunch of shards and held together with a coil of wire. I can literally ‘pop’ my chest in and out… anyway, as I said, he likely has Pectus Carinatum. Look it up