An EMG-based model to estimate lumbar muscle forces and spinal loads during complex, high-effort tasks: Development and application to residential construction using prefabricated walls

Residential building construction is moving toward more industrialized construction methods (e.g., use of prefabricated wall or panels), yet remains one of highest risk sectors for work-related musculoskeletal disorders. The centralized design process inherent in the use of wall panels offers the potential for proactive control of musculoskeletal risks, consistent with the prevention-through-design (or PtD) philosophy. As part of an ongoing effort to incorporate ergonomics into panel design, estimates of low back loading and injury risk were needed over a range of tasks performed during panelized construction. Here, a free-dynamic, three-dimensional, electromyography-based model was developed to provide such estimates, which was a modification of an earlier, relatively coarser model. Specific modifications included a more detailed representation of lumbar muscle anatomy and contraction dynamics, high-pass filtering of electromyograms to better represent muscle activation levels, and an enhanced calibration procedure through which five model parameters are specified on an individual basis and used to estimate lumbar muscle forces. With these enhancements, the predictive ability of the model was assessed over a wide range of simulated panel erection tasks. Predicted model parameters corresponded well with values reported earlier. Reasonable levels of correspondence were found between measured and predicted lumbosacral moments, though predictive ability varied between tasks and rotation planes. Relevance to industry: Wall panels are representative of the current trend toward increasing use of industrialized methods in residential construction. Model-based estimates can be used as part of a larger project to facilitate proactive design of residential construction using panelized walls in order to reduce musculoskeletal exposures and spine injury risks. (C) 2011 Elsevier B.V. All rights reserved.