I would stress varied exercises. Push-ups are known to exert stress on wrists, you need to do a variety of heavy lifting exercises (if you already have RSI, start gradually and watch YouTube videos how to do it right)

Also, stretch your arms.

For me, this book was a God-send:

https://www.amazon.com/Repetitive-Strain-Injury-Computer-Use...

I had pretty serious RSI issues a few years ago. Thanks to this book (and working out), I forgot all about it - you can do it, too!