I’ve found ergorest forearm supports work, along with a keyboard without a number pad to reduce mouse reach. I’ve swapped between various split keyboards over

I’ve found ergorest forearm supports work, along with a keyboard without a number pad to reduce mouse reach. I’ve swapped between various split keyboards over the years, starting with the beta version of the Microsoft Natural keyboard - sadly most of these have a number pad and that creates a mouse reach issue for some. These days I use a ten key less gaming keyboard. Also small free weights to exercise arms frequently during the day at the desk seem to help.