Evaluation of supermarket bagging using a wrist motion monitor.

The supermarket industry has one of the highest numbers of repeated trauma illnesses. Checkout departments have a rate of musculoskeletal injuries 2 to 3 times higher than that of other supermarket departments. The primary objective of this study was to quantify the wrist motions required to bag groceries using a wrist motion monitor. The wrist motions included deviations, velocities, and accelerations for flexion-extension, radial-ulnar, and pronation-supination directions. The independent variables were handle type and object location. Objects with finger-thumb couplings required more extreme pronations, greater wrist velocities for pronation-supination deviations, and greater wrist accelerations for pronation-supination deviations than did other objects. Objects with 10-cm hand couplings required more extreme flexion, larger ranges of movement for radial-ulnar deviations and pronation-supination deviations, and greater wrist velocities in the radial-ulnar and pronation-supination directions than did 5-cm objects. The right and front locations required more extreme deviations than did the left and back locations. Because finger-thumb and 10-cm hand couplings require larger wrist deviations and greater velocities, these objects may pose a greater risk of developing cumulative trauma disorders to the bagger. Potential applications of this research include engineering design of grocery packaging and supermarket bagging workstations.