index of difficulty

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A measurement of the theoretical difficulty of performing an aiming movement. It is based on Fitt's law, and is expressed as log2(2A/W), where A is the amplitude of the movement required and W is the width of the target. It indicates that the difficulty of a movement is jointly related to the distance a limb moves and the narrowness of the target at which it is aimed.

Subjects: Sports and Exercise Medicine.

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