This is called a static unmoving situation and can translate into immobility of joints and tension on the muscles that support those joints.I’m guilty of this and thought my stiffness was just part of getting old.
The biggest thing to help to prevent the stiffness is small breaks. I set a timer for every hour. Then I get up and take a walk. You can also stretch, do a five minute workout, whatever works for you. as long as you're moving those joints.This will help bring mobility back to the joints and stretch the muscles.
It’s also important to increase your activity when you finish writing; workout at the gym, take a yoga class or try Tai chi. These will help counter the time spent in one position, hunched over the computer.
You can also change the way you write. I know someone who uses a standing desk because of her back. There are other ergonomic desks you can try. Or use a fitness ball. It’s fairly inexpensive, helps with your core muscles and gets you moving a little more than a regular chair.You can also buy fitness ball chairs. (Who knew?)
If you're using a ball, keep your feet flat on the floor and you should be at eye level with your computer screen.
Whatever works for you, but you still need to take those breaks.
I’m bouncing along as I write this blog. I actually prefer it to the standard chair. And my timer just went so I’m off for a short walk to get more coffee. Anyone want to join me?