I had RSI years ago and needed to go to a physiotherapist for that and that was in a gym. I just had to train muscles. She also let me train my back. It was 10 maybe 20 times that I went there and training my back just a few minutes every time and it wasn't heavy, but after that the whole back pain was gone. I had had back pain for ages.Sometimes when I sit too long and get up quickly my back will have an ache for a few minutes until I straighten up fully. It started happening after my last surgery and I was told that I need to strengthen the muscles in my back. But it's been a year, so I don't know.