in the forearm and wrist occur in a typing position as the palms of your hand are turned face down and is parallel with the flat surface of the desk or floor. The majority of this turning involves the rotation of both forearm bones (the ulna and radius). Sustained pronation increases pressure on the forearm muscles and surrounding tissues and reduces blood circulation which can lead to fatigue and injury. Research demonstrates that a moderate elevation of the thumb side of the hand dramatically reduces this type of stress.
To reduce pronation Kinesis contoured keyboards elevate the thumb sides of the hands at a fixed lateral slope of approximately 20 degrees.