Occupational exposure to excessive physical demands (e.g., lifting, manual handing, or awkward postures) is a known risk factor for negative health outcomes including, pain, musculoskeletal disorders, sickness absence, and early retirement due to disability. Exposure is typically characterized by assessment of load amplitude, frequency, and/or duration. While considerable attention has been paid to exposure amplitude as a predictor of negative health outcomes, less consideration has been given to the exposure variation, that is, ‘the change in exposure over time’. A rich tradition of studies in sports physiology has shown that the temporal pattern of physical activity is an important factor affecting health, both in terms of positive effects (training adaptations), and negative effects (injuries). Further, on shorter time scales, the temporal pattern of exposure has also been shown to be a strong determinant of fatigue and endurance. Occupational health scientists and practitioners now agree that further consideration of exposure variation at work is important to better understand adverse health outcomes. 

To date we have only weak and sporadic evidence of 1) how to best measure variation (including appropriate metrics), 2) the extent to which variation occurs in current jobs, 3) how variation can be manipulated (i.e., effective interventions), and 4) health effects of interventions designed to promote variation in physical work demands. To this end, even studies devoted to attitudes in the workforce towards variation, or reactions to interventions intended to influence physical exposure variation, are rare in the current literature. This challenge needs to be viewed in the context of work changing continuously over time, including hybrid configurations of jobs, introduction of robotics and automation, and changing demographics in the workforce.  

This symposium will highlight the importance of considering variation, including methods for how variation can be assessed and examples of organizational strategies that can be used to increase variation at work.  Many of the presentations are based on work that will be part of an upcoming Festschrift to honour the career of Professor Svend Erik Mathiassen, who has considered variation throughout his career. The symposium will begin with a short introduction of the topic and of Svend Erik’s work made by the guest editors of the Festschrift (and symposium chairs), have five presentations (10 min. each) on variation, and will conclude with a discussion panel: 

Does job rotation lead to increased physical exposure variation within workers? A systematic review (Jennie Jackson)Exposure Variation Analysis (EVA) in Ergonomics and Health: A Review of Applications, Methods, and Future Directions (Luiz Brusaca)Variation at (shoulder) work: do sex and handedness matter? (Julie Côté)Associations of trunk motor variability with fatigue and low-back pain in repetitive lifting. (Divya Srinivasan)Quantifying task diversity in slaughterhouse work: Development of an exposure score for optimizing job rotation (Mikkel Brandt Petersen)panel discussion