If you’re sat your desk using a computer, the following you should check the following points
Make sure that the desk is high enough for you to comfortably rest your forearms on it, if it’s too low, you’ll either be forced to lean forward, or keep your forearms up.
This is extremely important. If you lean forwards, your upper back will curve away from the chair. If your forearms are left unsupported, you may develop RSI.
If the computer desk is too high, either adjust your chair, or sit on a cushion to raise yourself up. You must be able to support your forearms comfortably.
To increase your forearm support, ensure that your keyboard is flat, and rest your forearms on some magazines so that they’re level with, or slightly higher than, the keyboard. This will also lessen the strain when using the mouse.
If you’re using a separate computer keyboard and monitor, try to adjust the height of the monitor, so that it’s just below eye level. This won’t be possible when using a laptop, do not raise the height of your laptop as it’s more important to support your forearms correctly, than it is to adjust the height of the screen.
Position your computer keyboard towards the edge of the desk, If you have to stretch to reach the keyboard, either your back or shoulders will curve forwards.
Check your posture on a regular basis as it’s very easy to become engrossed in what you’re doing. As you concentrate more, you may find yourself bending forwards, tipping your head back, and slouching.