Sit up straight with your feet flat on the ground. Get a chair with good lumbar support. Adjust your monitor so that the top of it is as eye level. You've likely heard one or more of these kinds of tips for sitting at a desk and using a computer. They're all talked about in reference to computer ergonomics. UC Berkeley defines ergonomics as "the science of fitting jobs to people." And so by extension, it could be said that a major aspect of computer ergonomics is determining the best desk setup and computer accessories for people to use so that the experience is more natural.
As it turns out, a traditional computer mouse may not apply good ergonomics. I want you to do a little experiment to realize it. First, rest your hand and arm by your side. Take note of how it feels, and the orientation of your forearm in particular. Now move your arm into position as if you were using a mouse. Do you know what is happening inside your arm? Put your other hand around your arm to feel the change. The bones in your arm twisted, and the muscles tightened in order to do so. The orientation of our arm when using a mouse isn't even close to a natural resting position. Putting your body into unnatural positions for long periods of time can cause physical strain, or even injury.
Early last year I started looking for an alternative to your standard computer mouse. I switched from using trackpads on laptops to a desktop mouse after building my first PC, and it didn't take long for my use of a traditional mouse to start causing me discomfort, and sometimes minor pain, in my hand and wrist. (Before I go any further I'd like to say that myself nor anyone at Tested is offering medical advice. If you think you have a problem, please seek a medical professional if at all possible.)
Do as I say, not as I do. I've yet to see a doctor about my joint issues. My problem is likely two fold. First, when using a traditional mouse I don't use the proper technique; moving primarily with your shoulder and elbow. I'll move my wrist side to side, and plant my wrist to use only my fingers. While this level of control is great for precise production work or playing first person shooters, it's also a fast track to a repetitive motion injury like carpal tunnel syndrome. Additionally, joint problems run in my family, specifically rheumatoid arthritis. That is very likely not doing me any favors. As a result of these factors I'm not able to use a traditional mouse for long periods of time.
So I started usng a vertical mouse.