I am right handed. But I purposely mouse with my left hand.
A couple of years ago, I started having right shoulder problems. I would sit down at the computer and after a while my right shoulder would start to bother me. It wasn’t painful. But it was uncomfortable enough that I noticed it.
At first I just ignored these little “niggles” and got on with whatever computer work I needed to do.
Those “niggles” were my body whispering to me: “Something is amiss. Nothing bad is going to happen right this moment. But I am giving you adequate warning to do something about it soon so something really bad doesn’t happen in the not too distant future.”
I confess, I did not listen.
Things did not get better. In fact, the discomfort in my right shoulder would appear sooner and sooner after I sat down at the computer. It got to the point that just reaching for the mouse would set it off.
Resting and coming back to the computer did not help.
Because when I came back to the computer I was still moussing the same old way that was directly causing the pain.
I needed to do my moussing differently.
I have a wireless keyboard, so I tried sliding the keyboard over to the left so I could bring my mouse in closer when I was using it. This made my shoulder feel better.
But that was not a workable solution as often I am going back and forth frequently between moussing and typing and I needed my keyboard centered in front of me.
What I learned from this experiment was that my shoulder was happiest when my hands stayed within the width of my shoulders. The further outside the width of my shoulders my hands went, the more uncomfortable my shoulders were.
Ask any ergonomics consultant and they will tell you exactly what I found out by experimenting: try to keep your hands within the width of your shoulders.
The problem with my keyboard and most keyboards is that there is a number pad attached to the right side of the keyboard.
This means that if you use a traditional mouse as I do, it must be placed too far to the right to be comfortable. Each time you reach for it you are moving your right hand outside the width of your shoulder and that taxes the muscle.
But there wasn’t a number pad attached to the left side of my keyboard. So, I decided to try moussing on that side. It solved my problem immediately. It took me about 3 weeks to get used to moussing with the left hand. I was a bit slower at first and I had to pay more attention to it but it was well worth the effort. And it feels great to use my left hand as most of the time my right hand does most of the daily chores.
Check out this very good video by the Ergonomics Guy on this topic.