Dependence of finger pinch force on width and position of fingers

In order to utilize forces of finger muscles as a biomedical index, fundamental research on the forces was made using a finger dynamometer we made. This is an apparatus that can measure a force pinched by a pair of fingers: a thumb and a forefinger. The obtained results are summarized as follows:

(1) The largest force measured by parallel-shaped fingers is obtainable for L~1.4cm with best reproducibility of measurements and without discomfort pressure on fingers, where L means distance from the tip of the thumb.

(2) The pinch force measured by straightly stretched fingers does not depend on width between the thumb and the forefingers, where the best reproducibility of the measurement is obtainable when the fingers are parallel.

(3) The pinch force measured by C-shaped fingers does not depend on width of fingertips, where this pinch force is 0.6 times as small as that measured by parallel-shaped fingers.