The effect of handling products of different weights on trunk kinematics of supermarket cashiers

This study analysed the effect of handling products of different weights on trunk kinematics of supermarket cashiers. Eight participants performed a simulated task involving handling products of light (0.2 kg), intermediate (1.0 kg) and heavy (5.0 kg) weights, while 3D images of the trunk were collected. Light products required negligible changes in the trunk movements, while intermediate and heavy products caused greater amplitude of trunk flexion movements. Lateral trunk leaning increased as the weight of the product increased. Rotational movements of the trunk were not affected by the load weight, although rotation to the right (grasp) was up to four times greater than that to the left side (deposit). The data provided evidence against checkouts that require large amplitude of movement, which are repeated frequently each day. Postural problems may occur among checkout cashiers due to the strain imposed during the task. Supermarket cashiers remain at a high risk for occupational injury due to biomechanically incorrect workstations. Studies designed to quantify the impact of the workstation over the operators’ movements are required.