## 2 Materials and Methods
### Participants  
Participants were assigned to identical shift schedules. The range of their employment duration exhibited a moderate diversity, spanning from as short as half a year to as long as forty years, with an average tenure of 12.3 years. Our participant group consisted of two distinct categories: 42 individuals--machining workstation employees (MWEs) and 44 assembly workstation employees (AWEs). The MWE group had an average age of 41.9 years, with their body mass averaging at 79.9 kg and an average height of 1.76 m (Table 1). These employees were distributed across 12 different devices. In contrast, the AWE group, working on nine devices, were relatively younger, with an average age of 35.5 years, a body mass of 69.2 kg, and an average height of 1.69 m. Eligibility for participation in this research was determined based on specific inclusion criteria. Participants were required to have a minimum of six months of experience at their respective workstations. Additionally, the age cap was set at 60 years. An important health-related exclusion criterion was the absence of clinically diagnosed chronic or recurring musculoskeletal pain that might influence the participant's range or speed of movement, such as chronic lower back pain, joint pain associated with osteoarthritis, or ongoing pain resulting from prior musculoskeletal injuries. Mild or temporary musculoskeletal discomfort was not grounds for exclusion.  
Prior to the initial study, we conducted a comprehensive evaluation of manufacturing (MWE) and assembly (AWE) workstations in relation to work-related risk factors. These evaluations, carried out triennially, involve a series of \"ergo-checks\"--initial assessments for potential risk factors in the workplace environment. The methodology for these ergonomic assessments entails employing a bespoke risk evaluation checklist, designed in-house to identify high-risk factors. Repetitive movements are analysed in alignment with the European standard for handling of low loads at high frequency [35] and the OCRA method, while tasks involving the carrying, pushing, and pulling of objects are evaluated according to additional standards [36; 37]. One-handed lifting tasks are assessed following the standard for manual handling of machinery and component parts of machinery [38] whereas two-handed lifting tasks are examined using the NIOSH norm. Throughout the data-collection process, adherence to established ergonomic standards is maintained to ensure consistency and reliability.  
This research project received approval from the company's Health and Safety division and garnered support from the human resources department. The biomechanical procedures were ethically conducted in compliance with the Declaration of Helsinki on human experimentation. The study received approval from the Rector's Committee for Research Ethics at Wroclaw University of Economics and Business (case no. 33/2020). All participants were fully informed about the study's objectives and procedures and provided their informed consent, including permission to publish the data in an anonymised format.  
\begin{table}
\begin{tabular}{l l l} \hline \hline
**Parameter** & **MWE Group (n = 43)** & **AWE Group (n = 43)** \\ \hline Age (years) & 41.9 \(\pm\) 9.6 & 35.5 \(\pm\) 9.5 \\ Body mass (kg) & 79.9 \(\pm\) 13.6 & 69.2 \(\pm\) 13.3 \\ Bod height (m) & 1.76 \(\pm\) 0.07 & 1.69 \(\pm\) 0.10 \\ Work experience (years) & 12.8 (0.8–40) & 11.4 (0.5–32) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of demographic characteristics between machining workers (MWEs) and assembly workers (AWEs). Values are presented as the mean \(\pm\) standard deviation, with ranges indicated in brackets for work experience. A statistical analysis using the t-test for independent samples revealed no significant differences between the groups (\(p\) > 0.05).