An ergonomic evaluation of knives for two poultry cutting tasks

The poultry deboning tasks, a hanging cut and a table cut,were stimulated in the laboratory. Six different knives, angled at -30, 0 and +30 degrees from the axis of the handles, and with two handle diameters, 3.43 and 4.09 cm, were utilized. Two goniometers measured wrist flexion/extension and radial/ulnar deviation. A specially instrumented glove with force sensitive resistors recorded grip force. Smooth, rectified flexor digitorum profundus electronyogram signals were also recorded. The traditional straight knife performed worst under any condition that was tested. A -30°-blade, in adagger grip, was best for the table cut (minimizing wrist extension, ulnar deviation, and the ranges of flexion/extension and ulnar/radial deviation), while the +30°-blade, held normally, was best for a hanging cut (minimizing the flexion/extension range, ulnar/radial deviation range, and the maximum extent at extension and flexion). Handle diameter was not significant.