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Minicute > Support |
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Mouse and Keyboard use in relation to RSI |
- Once described in the Western Journal of Medicine as a manifestation of an occupational epidemic the mouse has become essential to the everyday use of computers. Although being increasingly used the device itself hasnt fundamentally changed in design since its invention in 1968 by Douglas Engelbart. Today there are dozens of variations of the mouse such as, inverted mice also known as trackballs, hand held pointers, and countless ergonomically designed devices claiming to reduce or stop RSI. Some of these devices may in fact actually work as they claim but CTS and what is now being called MAS Mouse Arm Syndrome are still a workplace plague spreading to where-ever computers and mice are found.
MAS - Mouse Arm Syndrome is a form of RSI - Repetitive Strain Injury has been studied extensively in a number of countries. Today it is well known that prolonged use of a computer mouse can cause pain, stiffness and often even permanent damage to the muscles and tendons of the human body. Those who sit for long duration behind the computer without breaks may, over a period of time, develop RSI (Repetitive Strain Injury). This can lead to Mouse Arm, which relates directly to the prolonged use of the mouse.
- Mouse vs. Keyboard
It is very likely that prolonged repetitive use of both the keyboard and the mouse can contribute to the onset of RSI. Some recent studies have found an increased risk associated with the mouse as opposed to the keyboard.
One recent study in particular conducted in Denmark which involved nearly 10,000 people suggested that using a mouse device for more than 20 hours per week was associated with a risk of developing C.T.S. and in comparison found no significant risk associated with the keyboard. It has been estimated that one individual who uses a mouse on daily basis can turn out over 2,000,000 mouse clicks a year and travel over 100 km on there mouse pad and a proportion of this distance is attributed to just fidgeting about and moving unnecessarily over the mouse pad. These movements do not take into account the amount of time the hand is just holding onto or hovering over the mouse, during which time the muscles and tendons in the hand and wrist are tensed and stretched. A recent survey fielded for one of the largest mouse manufacturers in the world questioned 1000 internet users and found that 63% of respondents spent more time holding their mouse than any other commonly held objects including cell phones, remote controls steering wheels or even their lovers. The same manufacturer is currently turning out 270,000 units each day or 6,000,000 per month. Given these figures it seems likely the term Mouse Arm Syndrome will be heard more often in the future.
- Physical effects on muscle and tendon groups of mouse use
Below are some of the major problems when using a mouse with relation to which muscles and tendons that are mostly affected by repetitive and / or prolonged mouse usage.
Starting with the hand. When the hand is completely relaxed the fingers flex and the hand is half way between a fist and completely straight. This balances the tension between the flexors and extensors of the fingers. When the flexors are tight they can trap the median nerve and cause what is commonly but called "carpal tunnel syndrome." When the extensors are too tight they can cause epicondylitis or "tennis elbow." They can even trap the radial nerve and cause numbness in the hand. In order to prevent this the hand must be positioned so that it is not too straight and not closed too tight ie- relaxed .A regular mouse causes the extensors to tighten in order to hold the fingers slightly above the mouse buttons. They are under slight tension all the time which causes the cumulative injury effect.
Next the wrist. With a regular mouse the wrist is usually extended slightly. This is not a major problem but the tension on the wrist extensors to maintain this position is definitely a problem. When using a mouse the weight of the arm and shoulder is supported by the trapezius and levator scapulae muscles. The scalenes also tighten as the shoulder is supported. This is because you cannot rest the weight of the arm and shoulder on the mouse while using it. Almost everyone has felt that "burning" in the muscles between the neck and shoulder after using a mouse for any length of time. This causes damage to the tissues that builds up over time. These symptoms can be painful in the least and debilitating for an individual in extreme cases, which are becoming more common.
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