I started back playing DB 4 years ago after a 35 year layoff. I started back very slowly. Open strings. Then scales. Then Simandl method book etudes. Careful about my ergonomics. I'm in my late 50's now. After a year or so and 15 or 20 minutes of playing I started to get tightening in the muscle between my thumb and index finger on my bow hand. I play French Bow. Once I joined a community orchestra it became apparent that very physical passages would be almost impossible as the muscle nearly froze up and had no flexibility after 15 minutes. So I looked up and then I went to a hand specialist who works with musicians in New York. She gave me mostly shoulder exercises that amount to stretching with low weights. She told me to do them every day. I do. after 4 weeks, I was playing nearly pain free and I asked for more exercises. All told, I spent $450 on her services. After three months I am a new musician and I can produce a big deep sound and play with no pain, with flexibility and power. I have amazing flexibility and can reach around my back and up to my shoulder blades with my hands--something that was unthinkable 3 months ago. I added in core exercises and now I can walk for miles like it's nobodies business and run up and down subway stairs. The shoulder exercises for my hands take about 20 minutes. The core exercises add another 20 minutes. I try to do them every day but have to miss every once in a while or do 10 reps instead of 15 or 20. If anyone would like more information please let me know. I was speaking with a Double Bass Player in a major orchestra, and he told me that most older bass players do not get PT for their injuries--they just let their playing go down hill if they are having problems and then retire. I was puzzled and asked him why and he said, sad to say, they are too macho to entertain the idea of physical therapy. I think and hope attitudes are changing.