I don't know all of the personal details here -- but, if your muscles are underdeveloped your at risk for RSI issues. I'm taking a guess, at that height and weight your muscles are underdeveloped.
Since I switched to very basic body weight strength training nearly 2 years ago, problems I thought I would have until I died vanished. Nothing I ate or drank, no amount of aerobic exercises did anything to address those issues.
You should not be developing back pain from standing. Everything else should be getting sore. Back pain, that I've seen, generally occurs from people who either slouch forward at work, have major stress issues, or have some type of actual injury.
Great, but how much can you squat or deadlift relative to your bodyweight? Your posterior chain, from your mid-back down to your ankles, is far more important to your long-term stability and comfort.
It's key to your complaint of discomfort standing up, and it's key to avoiding back or knee problems long-term.
Since I switched to very basic body weight strength training nearly 2 years ago, problems I thought I would have until I died vanished. Nothing I ate or drank, no amount of aerobic exercises did anything to address those issues.
You should not be developing back pain from standing. Everything else should be getting sore. Back pain, that I've seen, generally occurs from people who either slouch forward at work, have major stress issues, or have some type of actual injury.