Effectiveness aside, how skeptical were you when you heard that? It's easy to hear these explanations in hindsight, but I bet at the time you'd be, like, "What kind of advice is that? Are you just using a medical-grade magic 8 ball? 'Swim more'? "
Sorry, my original answer was cut short by an interruption!
She was a great physio -- afterwards I asked her to come back about another complaint (running injury) and she was the only physio (of 3) to improve that too. So it wasn't just "go swim more" but "do a bunch of things".
First she explained why I was getting RSI, which was due to overreaching caused by bad posture, laptop usage, etc. Gave me advice on how to stop it getting worse, which worked. I bought an ergonomic mouse, avoid some keyboard shortcuts, changed my chair.
Then she advised me to swim and walk (!) more. I had no expectations, just followed her instructions. I was particularly surprised to find that walking helped so much, but without doubt swimming was key. Swimming is so good because it works out so many muscle groups and stretches and expands your body. A colleague later told me that he'd had RSI and took up swimming to cure it.
My RSI is pretty much gone now, even working very long hours, but I've continued to swim every day. I'd recommend it, as it's much better than running for your joints and also avoids lifting weights, which I've never been keen on due to the competitive (slightly obsessive!) attitudes of those who attend crossfit, etc. Being able to swim well is a really useful skill.
