Wow, I love the diversity to the answers. I do believe a person should be diagnosed by a physician or physical therapist. What could appear to be a rotator cuff injury could actually be cancer. So diagnosis is best left to professionals. That being said, I believe a trainer can be very beneficial to the injured or limitations client. Most of my clients tend to have some injuries, limitations, surgeries that limit range of motion, etc. And I myself am in my 50’s and have experienced some limitations. From life experience, I have learned rehab moves and strengthening moves to help my clients. I also teach yoga which tends to strengthen and balance out our weak areas. With assessment of each individual I am usually able to get them some release in their pain and a little farther range of motion. So a good, experienced, observant, and intuitive PFT could enhance healing for special populations once diagnosis has been made.