Kinematic and electromyographic assessment of manual handling on a supermarket green- grocery shelf.

BACKGROUND: There are few epidemiological data regarding musculoskeletal disorders (MSDs) in retail industry. Biomechanical risk assessment in ergonomics is commonly performed in retail sector using standardized protocols. However, such protocols have numerous limitations, such as the lack of objectivity or applicability and restrictive conditions. OBJECTIVE: The aim of this study was to analyze one of the most commonly used shelves in vegetable and fruit departments in order to investigate the effect of different shelf levels (i.e. with variations in height and horizontal distance) and load weights on the workers' biomechanical load. METHODS: We investigated trunk, shoulder, elbow, hip, knee and ankle joint ROMs, as well as the mean and peak EMG values of the upper limb, trunk and lower limb muscles. RESULTS: We found that shelf level has a significant effect on most of the parameters examined, whereas within this limited range of 6 and 8 kg, weight does not affect the biomechanical load. We also identified the shelf levels that place the least and most strain on the musculoskeletal system. CONCLUSIONS: We therefore recommend that the height and horizontal distance be carefully considered when shelves are being designed. Kinematic and EMG approach may help to objectively assess shelf-related risks. Our findings are in agreement with RNLE LI values and therefore support RNLE.

Biomechanical evaluation of supermarket cashiers before and after a redesign of the checkout counter.

An experiment was carried out on supermarket cashiers to evaluate the time, kinematic and electromyographic changes, in both sitting and standing positions, following the redesign of a checkout counter. The novelty of the prototype checkout counter is a disk wheel placed in the bagging area, which is designed to avoid the cashier having to manually push products along the bagging area. The kinematic evaluation was based on the upper limb and trunk range of motions (RoM). The electromyographic parameters assessed were mean and maximum muscular activations. Three factors were taken into account: design (before and after redesign), posture (standing or sitting) and bagging area (anterior or posterior). The results show that the RoM values are lowest after the intervention and in the standing position. Mean and maximum muscular activation patterns are similar. Differences related to the bagging area in which the goods were released also emerged. The disk wheel represents a valid aid for reducing biomechanical overload in cashiers; the standing position is biomechanically more advantageous. Practitioner Summary: EMG and optoelectronic motion analysis systems are useful for the quantitative assessment of the effects of the redesign of the workplace biomechanical risk. Our results suggest that a disk wheel positioned in the bagging area reduces the biomechanical risk for cashiers and increases time spent resting.

Kinematic analysis of post office employees' workstations.

This study analyzed a post office clerk's tasks, comparing two workstation models. The clerk was facing the client in one, and seated at 45 degrees to the counter in the other. We analyzed the most frequent tasks and those presenting the most critical points: 1) payment of a postal order; 2) accepting a registered letter, breaking them down into subtasks. We used an optoelectronic system for kinematic analysis, and calculated the range of motion of the trunk and arms in the three spatial planes. The 45( position required less torsion of the trunk and head when using the printer, placed to the left of the employee. A larger worktop improved the workstation, leaving more room for equipment and allowing the worker to sit frontally to the monitor. However, this solution involved a shorter distance between the worker and the client with longer extension of the shoulder and elbow and less trunk flexion. These findings suggested a modification in the layout that shortens the distance between the worker and client.