Just off the top of my head, he has to be at least 60. He was in his 20s or 30s in the Hulk, and that was in the late 70s or early 80s. Also, I think he has a physical condition (bone deformity, etc), which gives him a very unusual facial structure as well as his hearing disability. I'm not sure about exactly what that health issue is, but I remember hearing something about it. As with Arnold or Jack LaLanne, a great physique takes on a different look after retirement age, I guess.
Charles