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Investigating reduced bag weight as an effective risk mediator for mason tenders.

Davis KG; Kotowski SE; Albers J; Marras WS
Appl Ergon 2010 Oct; 41(6):822-831
Masonry workers face some of the highest physical demands in the construction industry where large bags of masonry material weighing 42.7 kg are commonly handled by mason tenders who mix the mortar, distribute mortar and bricks/blocks, and erect/dismantle scaffolding throughout the day. The objective of this study was to determine the effectiveness of using half-weight bags (21.4 kg) on reducing the biomechanical loading, physiological response, and perceived exertions. Ten male subjects performed asymmetric lifting tasks simulating unloading bags from a pallet. Muscle activity, trunk kinematics, heart rate, blood pressure and subjective rating data were collected. Spine loads were predicted from a wellvalidated EMG-assisted model. Bag weight, lift type, bag height at origin, and asymmetry at destination significantly impacted the spine loads. While there was a 50% reduction in bag weight, the peak loads for the half-weight bags were only 25% less than the more available full-weight bags (a reduction of about 320 N of shear and 1000 N of compression). Lifts allowing movement of the feet reduced the loads by about 22% in shear and 27% in compression compared to constrained postures. Interestingly, cumulative spine loads were greater for the lighter bags than the heavy bags (w40%). The subjective ratings of exertion and risk were significantly lower for the lighter bags. Relevance to Industry: The reduction in peak spine loading for the half-weight bags, particularly at the higher heights and when the feet were allowed to move could significantly reduce the injuries of masonry workers. However, there were trade-offs with cumulative loads that may minimize the reduced risk. Overall, given the limited amount of time lifting bags, the reduction of peak loads...
Masons; Construction; Construction-materials; Construction-workers; Weight-factors; Physical-stress; Physiological-measurements; Physiological-response; Physiological-stress; Physiological-testing; Physiological-fatigue; Physiological-function; Heart-rate; Blood-pressure; Muscle-function; Muscle-stress; Muscles; Construction-industry; Biomechanics; Humans; Men; Manual-lifting; Manual-materials-handling; Materials-handling; Musculoskeletal-system; Ergonomics; Author Keywords: Spine load; Productivity; Low back injuries
Kermit G. Davis, Low Back Biomechanics & Workplace Stress Laboratory, University of Cincinnati, Cincinnati, OH 45267-0056, USA
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Journal Article
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NIOSH Division
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Applied Ergonomics
Page last reviewed: July 15, 2022
Content source: National Institute for Occupational Safety and Health Education and Information Division