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Introduction: Occupational exoskeletons (OEX) to reduce biomechanical workload and have been suggested to decrease musculoskeletal disorder (MSD; including back, neck and shoulder pain) risks. Many workers with MSDs believe they are directly caused by physical work, such as lifting. Ergonomic messaging can sometimes unintentionally reinforce these beliefs, potentially leading to nocebo effects where negative expectations influence health. Despite decades of research, evidence causally linking occupational load to MSDs is limited. Advances in pain research suggest that multiple dynamically interacting biopsychosocial factors contribute to MSDs. Also, nocebo and placebo effects have not been studied in OEX use, although they are likely relevant in this context.

Aims:

1. Investigate placebo and nocebo effects in OEX use during work;
2. Assess novice user experiences and examine how age and sex may influence device acceptance.

Methods: A three-week A-B-A Single Case Experimental Design (SCED) study. Workers from healthcare and construction, new to OEX, will be assigned to an experimental group (receiving detailed OEX benefits, risks, and uncertainties) or a control group (receiving standard instructions). Phases include a baseline week (regular work), an intervention week (OEX use with varied support), and a reversal week (regular work). Daily and weekly surveys will capture participant experiences of support, reassurance (reduced fears about pain), discomfort, productivity, and usability, followed by a final interview exploring adoption factors. Four passive OEX models for back and shoulder support will be tested, with comprehensive questionnaires collecting user experiences. Analyses will include repeated measures and mixed ANOVAs, paired t-tests, and descriptive statistics. Expected nocebo effects include lower reassurance and baseline discomfort scores in the experimental group, while placebo effects are expected as higher experienced OEX support, productivity, and acceptability scores.

Discussion: This innovative study is the first to explore placebo and nocebo effects in OEX use, utilizing a novel SCED approach in OEX research. Findings will advance understanding of biopsychosocial factors in OEX wear, highlighting OEX potential to enhance work sustainability and health in physically demanding roles. Preliminary results will be presented during the congress.