I'd guess the walking probably contributed more. I've had issues with my back for most of my life. When I'm physically active (walking, resistance training, et

I'd guess the walking probably contributed more. I've had issues with my back for most of my life. When I'm physically active (walking, resistance training, etc) and strengthen my core, I find that the problems subside to the point where I rarely hurt myself. It still happens but with much less frequency. Posture and avoiding RSI-like outcomes helps too, but I genuinely think strengthening related muscle groups helps more. Not a doctor though, so take this opinion with an equivalently-sized grain of salt!