1. The shortcomings of the normal
keyboard - the factors that cause
stress at the wrist
Place both your forearms on the desk without bending your wrists, as you would place them at a normal typewriter. If you look at the relation between the surface of the back of your hands and the horizontal plane of the desk, you will notice that the surface of the back of your hands is inclined (and not parallel to the horizontal plane of the desk).
 This incline is made possible due to the forearm's pronator and supinator
muscles stretching in opposite directions.
Moreover, if you observe your fingertips carefully when the back of your hand is inclined naturally without the wrists bending, you will notice that the tips of the thumb and index finger are not at striking position of the home position key.
 In order to strike the home position key, you have to rotate your forearm
inward as the surface of the back of your hand becomes parallel to the
horizontal surface of the keys;
then, you have to bend/stretch your wrist to reach the home position key.
The independent rotation action and the bend/stretch action are both natural operations of the joints, but the combination of rotation and bend/stretch, i.e. the “twist” action, will cause stress at the wrist.
A typical symptom of the “twist” action is the carpal tunnel syndrome.
During the development of this syndrome, a sharp pain shoots through the carpal joint, making it difficult to stretch the fingers.
An easy way to understand this is as follows. Wrap four fingers around the thumb of the same hand and clench the fist. Now, try to rotate your hand inward and bend your wrist towards the side of the little finger.
The stress at the wrist on the side of the thumb leads to pain. (Caution: Do not attempt this exercise with much force!)
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