Nowadays, there is more mouse use than ever. Websites and other new software require more mousing than word processing did in the past. Although mousing is fast and efficient, it can also cause ergonomic risk factors such as these:
Force – Some mouse buttons are sticky requiring more force from the fingers. Also, the farther away the mouse is the more force is required from the arm and shoulder to reach.
Repetitive motion – Mousing requires repetitive motion of the fingers, wrists, arm and shoulder.
Overuse – If you mouse on a frequent basis, you are using muscles in your fingers, wrists, arms and shoulders continually. If you mouse all day at work and then go home to use the computer at night, these muscles don’t get a break. Each day you do this, the muscles have less time to recover, increasing the chance for injury.
Contact stress – The most common place for is contact stress when mousing is on the inside of your wrist where the carpal tunnel is located. This area does not have a great deal of protection from contact stress. There is only a thin layer of skin (no cushioning fat) with the tendons and veins visible and exposed. When contact stress is placed on this area, pressure builds up in the carpal tunnel causing narrowing and reduced nerve and blood supply. This puts people at the risk of carpal tunnel syndrome and tendonitis. Another area to watch is the forearm. Depending on where the mouse is located, some people rest their forearms against the sharp surface of the desk causing an even more forceful and localized type of contact stress.
Awkward postures – The mouse is usually located to the right of the keyboard beyond the numeric keypad. Because of this, reaching with the right arm is required resulting in awkward postures. The elbow can’t stay at 90 degrees of flexion and it can’t stay next to the torso where there is little to none requirement for muscle use. The wrist also becomes more extended the farther away the mouse is. With each degree of extension, the awkward posture becomes more pronounced and the risk for injury increases.
To make matters worse, when there is a combination of risk factors – for example, repetitive motion and awkward postures together – the risk for injury increases. But there are many ways to combat risk factors by improving technique which I will discuss in my next post.