Evaluation of a participatory ergonomic intervention aimed at improving musculoskeletal health.

BACKGROUND: Participatory ergonomic (PE) interventions have been increasingly utilized to deal with work-related musculoskeletal disorders (WMSD). METHODS: Using a longitudinal quasi-experimental design, a PE process was launched at one depot of a large courier company, with a nearby depot serving as a control. Evaluations focused on 122 employees across the two depots who participated in both pre- and post-questionnaires. An evaluation framework assessed the process of implementation, changes in risk factors, and changes in musculoskeletal health outcomes. Partial and multiple regressions explored the relationships in the evaluation framework. RESULTS: Changes in work organizational factors had a consistent impact upon changes in health outcomes. Greater participation in the process was associated with increased levels of job influence and communication (P = 0.0059 and P = 0.0940 respectively). Improvements in communication levels were associated with reduced pain intensity and improved work role function (WRF) (P = 0.0077 and P = 0.0248 respectively). Lower levels of pain post-intervention were related to greater WRF (P = 0.0493). CONCLUSIONS: A PE approach can improve risk factors related to WMSD, and meaningful worker participation in the process is an important aspect for the success of such interventions.

Study of the effectiveness of a participatory ergonomics intervention in reducing worker pain severity through physical exposure pathways.

A participatory ergonomics programme was implemented in an automotive parts manufacturing factory. An ergonomics change team was formed composed of members from management and the organized labour union. It was hypothesized that the physical change projects implemented as part of this process would result in decreased worker exposures to peak and cumulative physical demands and reduced worker perceptions of physical effort and pain severity. A quasi-experimental design was employed, utilizing a sister plant in the corporation as a referent group. A longitudinal questionnaire approach was used to document pre-post changes in worker perceptions. In general, the physical change projects were rated as improvements by workers and were successful at reducing peak and/or cumulative mechanical exposures. However, there were few systematic changes in perceived effort or pain severity levels. Explanations include the confounding effects of differential production rate and staffing changes at the intervention and referent plants and/or insufficient overall intervention intensity due to a relatively short intervention period, plant and team ambivalence towards the process and the low overall impact on exposure of the particular changes implemented.

The effects of job rotation on the risk of reporting low back pain.

Job rotation has been widely recommended as an administrative control to reduce the risk of developing work-related musculoskeletal disorders. However, evidence of its benefits are hard to find in the literature. The effect of job rotation on predictions for the risk of reporting low back pain was estimated using Low Back Pain Reporting (LBPR) and Time Weighted Average (TWA) approaches. Index scores calculated using the peak hand force, the peak L4/L5 shear force and the L4/L5 moment cumulated over the entire shift were used to estimate the effects of job rotation on the probability of reporting low back pain. Simulations of realistic rotations between two jobs showed that workers in low demand jobs who rotate into higher demand jobs experience a linear increase in reporting probability using the TWA approach. With the LBPR approach a step increase in reporting probability occurred because of the immediate exposure to the peak loading parameters associated with the more demanding job. With a 50-50 rotation the TWA and LBPR index scores increased by 39% and 57%, respectively. With the LBPR approach the redistribution of risk was not uniform with job rotation. The increase was greater for those who rotated into the demanding job compared to the reduction experienced by those who rotated out of the demanding job. The effects of job rotation are not easily estimated because of the complex effect that mixing jobs has on peak and cumulative tissue loading.