## 2 Materials and Methods  
A review was conducted on papers with focus on occupational exoskeletons, published from 2011 to the first quarter of 2023 in the scientific database Science Direct, PubMed, IEEE Xplore and in the public document repositories of the US Occupational Safety and Health Agency (OSHA) [15] and the European Occupational Safety and Health Agency (EU-OSHA) [16]. Research studies, conference proceedings, literature reviews, guidelines, research projects, and reports, were included in this study. Figure 1 illustrates an upward trend in the number of publications related to exoskeletons over the period from January 2011 to March 2023. The picture shows a steady increase in the number of publications each year, indicating a growing interest in this topic among scholars and practitioners. This trend indicates that the subject of occupational exoskeletons is gaining increased attention from the scientific community as well as authorities like as the US OSHA and the EU-OSHA, which is expected to lead to new breakthroughs and improvements in the field, in the near future.  
The keywords adopted for the search are \"exoskeleton\", \"industrial\" and \"occupational\". A total of 4197 documents was collected using the combination of such three keywords, of which 121 were included in this study (Figure 1). The selection of this limited amount of publications from the literature (4%) was based on the article selection protocol in Figure 2, for considering only those that align with the objectives of the present study. Specifically, the article selection protocol consisted of three phases. The first contained the inclusion criteria related to the characteristics of the article: language (i.e., English); type of document (i.e., research studies, conference proceeding, review, guideline, research project, or report); year (i.e., published from January 2011 to March 2023). The second phase of the protocol employed an inclusion condition for the extraction of the documents that focused on the interaction between the user and the occupational exoskeleton, while disregarding publications that solely focus on exoskeleton development and design stages. The condition was verified by reading the document title and the abstract. Then, in order to identify the aspects related to the objective of the literature review, four research questions were elaborated:  
Q1 \"Which parameters were analyzed to investigate the interaction between the user and the exoskeleton?\"; Q2 \"What were the effects of using the exoskeleton on the user's health and safety?\"; Q3 \"Did the use of the exoskeleton have a demonstrable impact on the operator's job performance during the defined task?\"; Q4 \"What was the impact of the exoskeleton on user acceptance and perceptions?\". These research questions guided the  
Figure 1: Publication trends on the topic of occupational exoskeletons from January 2011 to March 2023.  
inclusion condition in the third phase of the protocol and the documents were thoroughly read. Data from the 121 documents that met the inclusion criteria and conditions were analyzed and organized according to the research questions Q1, Q2, Q3 and Q4. Hence, data on the exoskeletons investigated in the selected publications were categorized based on the type of exoskeleton (active, passive or hybrid), the technology readiness level (prototype or commercial device), and the supported body area (e.g., spine, lower limbs and upper limbs). An assumption is made on the findings in this paper, i.e., the present review synthesizes information gathered from various studies that have examined the utilization of exoskeletons across different types and sectors, in regard to the impact on workers' health, safety, performance and acceptance. Data on the same exoskeleton that appeared in multiple papers, e.g., in a research paper and in a review study, were included in the present research once. The full list of the 121 publications included in this research is in the document Appendix A.