@contentandwell I wasn't exactly a trainer. I was a high impact aerobics instructor, which they have since found is too hard on the body. I did work for a kinesiologist though and so we were trained how to do the moves that we were doing. We also did floor exercises and stretching but no weights. So I had a certain amount of kinesiology training with all that. I have been to a weight trainer at the gym and I found that using weights that are too heavy just makes the problems worse. I'm sure you realise that, plus too many repetitions are not good. That is I think what gave me a lot of my skeletal problems, over use and too many repetitions. So ease into new exercises very carefully. I also think that music with a lot of energy can be dangerous because I used to fly when we used the high energy music. I loved it because it was like high energy dancing and I used to put the tapes together with really high energy music.
I think some of the You Tubes online are good for demonstrating how to do weight exercises and exercises for injuries. I know there are some good ones for thigh strengthening and it's worth a try. Strong thighs can also help the knees.