Physical workload and low back disorders: Does fairness matter?

Back ground: While evidence suggests that psychosocial aspects of work impact low back disorders, previous studies had methodological shortcomings. Using objective measures of physical workload and low back function, this prospective study examines the perception of fairness in the workplace as a moderator between physical workload and low back function.

Methods. Warehouse employees (n = 301) provided data at baseline and six-month follow-up. Perceptions of management fairness were measured in a questionnaire with a 23-item scale (Cronbach alpha = .94) developed from a previous qualitative study. Physical workload was assessed by an ergonomist through systematic observation, and the number of exertions that exceed the threshold limit value was calculated for each job. Low back functioning was measured using a lumbar motion monitor. Linear regression was used to examine the association between the change in fairness perceptions and change in low back function for three levels of physical workload.

Results: For the employees in low physical workload jobs, fairness perceptions were not associated with change in low back functioning. For those with medium physical workload, higher fairness at baseline was associated with improvement of low back functioning (b=.094, p=.038). For those with high physical workload, consistently low fairness scores were associated with worsened low back functioning (b=-.182 p=.037).

Conclusion: Employees' perceptions of management fairness moderated the relationship between physical workload and change in low back functioning, but the direction and magnitude of moderating varied across different levels of physical workload. Implications for future research will be discussed.