Collaborative project: Integration of activity-specific load alternation to reduce the physical demands during takt work

Status:

completed 08/2022

Aims:

The prevalence of repetitive work in the manufacturing industry contrasts with the health consequences for workers. For example, repetitive tasks are considered a major risk factor for the development of work-related musculoskeletal complaints and disorders. The aim of this research project is to provide proof of concept (PoC) that the integration of muscle-specific load alternations is a useful and appropriate approach reducing physical strain during cyclic, repetitive work. Based on this PoC, a methodology will be developed to enable occupational practitioners to integrate muscle-specific load alternations at workplaces with cyclic repetitive tasks. This approach aims to reduce the risk of musculoskeletal disorders (MSDs) and musculoskeletal complaints (MSBs) related to repetitive occupational work and to prevent occupational diseases in the long term.

Activities/Methods:

At the beginning, the requirements for the reference assembly process were defined on the basis of a literature research conducted for the proposal, interviews with experts from industry and collaboration of the Institute for Production Systems (IPS) of the TU Dortmund University and the Institute for Occupational and Social Medicine and Health Services Research (IASV) of the University Hospital Tübingen. Once defined, the experimental setup was derived, including an initial series of measurements, to generate the data basis for a reconfiguration of the assembly process. During the reconfiguration, successive partial activities with increased muscular demands in the upper trapezius muscle were interrupted by partial activities of lower muscular demands in order to give the muscles more opportunities for short-term recovery. In the subsequent data collection (PoC study), this reconfigured process with specific load alternations was compared with the initial reference assembly process. For this purpose, a total of 38 subjects were included in an experiment with within-subject design with measurement repetition. The influence of muscle-specific load alternations on muscular strain and complaint development was investigated objectively by means of surface electromyography (OEMG) and subjectively by means of physical complaints in the upper extremity. In addition, various work-economic, physiological, and subjective control parameters were collected to examine the comparability of the reconfigured assembly sequence with the reference process. The results were presented and jointly discussed in a final research committee meeting.

Results:

Within the scope of the research project, the potential superiority of the reconfiguration compared to the reference assembly process could not be confirmed due to a lack of significant effects. The relevance of the research topic for an ergonomic design of work systems was regularly emphasized by the research partners and the research advisory board during the project. In the course of the project, further research needs in different areas could be identified. These include the selection of load levels, learning times and effects, psychological effects on trapezius muscles and superposition effects. The identified research gaps are to be addressed by constructive studies in advance of a renewed examination of the research hypothesis.

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