His back injury: here's what happened... he overstrained/injured it during those strenuous activities in his youth. The intervertebral muscles (that link 2-3 vertebrae at a time) atrophied, as they do during injury. These musles stabilize the spine, and prevent it from moving in painful ways. Without exercises (like pilates bridges) to cause them to regenerate... he will always have pain.
I do recommend that he go to a physical therapist if he doesn't believe me, or even a spinal pain clinic to get a referral to a PT. Whatever. Even if its degenerative disk disorder, pilates are the most effective treatment.