If you are like most people, you hold on to your mouse the whole time you sit behind your computer, but you don't actually use it for most of that time! A lot of the time is spent reading, thinking, waiting or talking on the phone. Did you ever notice that your hand is 'hovering' on or over the mouse with your muscles tensed. By the end of the day you feel tired and stressed, your hand and shoulders are painful. This static muscle tension can lead to a more serious upper limb disorder.