Distribution of grip force in three different functional prehension patterns.

Normative data of the grip force distribution necessary to complete functional tasks are limited. Small force sensors have been specially designed for accurate measurement of the dynamic handgrip force distribution by attaching them to the palmar surface of the hand. Seventeen healthy participants performed three different tasks, each requiring a different functional prehension pattern. When cylindrical objects were manipulated, the highest average grip forces were found at the fingertips and the thumb, followed by the middle finger. In a spherical grasp pattern, the contributions by the thumb, ring and small fingers always exceeded 71% of the total grip force. The highest local forces of 9.9 N were measured when a zip was closed with a tip pinch. Individual finger forces were found to differ by gender, but not by hand dimension and age. The results are useful for biomechanical modelling of the hand, for designing ergonomic tool grips, and for evaluating hand function.