Everyone will have their own private wisdom to dispense on this subject… and here’s mine!
I think the most important thing to understanding these modern ailments of the body is they are not primarily the result of repetitive movement - the body, after all, is designed for repetitive movement. The main problem is lack of movement. That is, for eighteen hours a day we are holding our hands in a particular position, often under tension. It is this continuous strain that causes injury more than anything else.
The solution to this problem is to move - not once a day, but often, ideally continuously. Connective tissue thrives on movement - if you don’t move, tendons lose their elasticity because they are not extended to their full range, fascia become sticky and muscle fibers begin to adhere to each other. Massage is a useful tool to solving some of these problems (breaking cell-cell adhesions or stretching tendons by physical manipulation).
The other important thing to understand is that your body is a connected system. Your wrists may have problems, but it doesn’t stop there. The tendons in your fingers are connected to muscles running all the way up to your elbow; accumulated tension in your forearms may also translate into poor shoulder position (turning in instead of lying back); along with a small keyboard this might result in a narrowing of the chest muscles, which may produce a forward-leaning posture. This posture may result in “gargoyling”, sticking your neck forward to crane at a monitor instead of sitting with your head sitting on your spine. This puts your neck muscles (which are only supposed to stabilize your head, not support its weight) under continuous tension for often eight hours, resulting in strain in the trapezius in the upper back (I often feel it in the band running between the shoulder blades). All of this because of bad wrist positioning!
The answer is: don’t try to fix only your wrists. Your whole body is suffering. Fix your entire posture. Sit up. Don’t crane your neck forward, let it rest above your (straight) spine. Open your chest, so that your pectoral is not compressed and pulling your shoulders forward.
Echoing @Simon_Clift I highly recommend a Kinesis split-key keyboard. It’s not a panacea, but it’s a start - it will allow your chest to be more open as you type. Throw your fucking Apple chiclet keyboard against the wall, they are pain in a beautiful form factor.
But mostly, GET THE FUCK UP. Stop expecting your body to work correctly if you sit in one bad position for ten hours a day. Stop expecting your body to work correctly if you sit in one GOOD position for ten hours a day. Lack of movement is the main cause of your problems. Move - it improves elasticity, it increases lubrication of your joints, it prevents muscle atrophy. A standing desk is a common tool, but again, will not solve all of your problems.
In the end the modern work situation is just not designed for our bodies - we need better input devices, desks and monitors that allow more movement, more comfortable body positions, and discourage static postures. We can seek out some of these things already - but mostly it’s on us to pick up healthier body habits.
