The thing about rubber dome keyboards is that they are the cheapest kind of keyboard. So you'll find a lot of absolutely awful ones out there. For example, you'll find ones where the amount of force you need to push in the key is unpredictable (keys feel "sticky"). You'll find ones where it takes too much time for the keys to come back up after they're pushed down. You'll find keyboards that have almost no weight, so you can't type without moving around the keyboard.
In contrast, people pay $100-$200 for a mechanical keyboard (they are a specialty item) and the build quality reflects that. For that money, you usually get something which has a weight in it (so it doesn't feel like you're typing on a hollow plastic shell), has reasonable ergonomics, and key action that is at least tolerable.
I find that I am a heavy typer (I press the keys hard) and I could never get used to mechanical keyboards. I was always "bottoming out." Unfortunately, the hard stop on a mechanical is even harder than the hard stop on a rubber dome. It's like hitting a wall. There are mods you can make to mechanicals to fix this, but you have to do it yourself. (For example, you can put rubber bands underneath each key, to get a more gradual stop when you bottom out.)
Right now I use a good quality rubber dome keyboard with an included trackpad. I find that keeping the keyboard in the correct position on my lap is a lot easier when I don't need a keyboard tray. It really is all about ergonomics.
My advice to you would be to stop lifting weights for a while. Just use machines or something to avoid putting pressure on your wrists. And then get a good quality keyboard. You will need to try it out before you find the right one for you. You'll probably have to order a few online before you find one you like. You will also need to start using good typing posture so be sure to research that.
