Field assessment of biomechanical and physiological demands in sand and limestone bagging operations

Abstract

Bagging operations are common in the mining industry and are associated with numerous musculoskeletal injuries. To better understand the physical demands of bagging operations, field evaluations quantifying low back loading and physiological costs of bagging tasks were performed at two bagging operations. A biomechanical model employing electromyography (EMG) and goniometry was used to estimate lumbar compression and a portable metabolic system used to assess heart rate and oxygen consumption. Manual palletizing of bags was found to generate a load of approximately 1,500 Newtons on the spine, with a few larger loads of 2,000-3,000 Newtons. The average oxygen cost for stacking was 5.3 METS, indicating moderately intense physical activity. Bag filling resulted in lower lumbar loads and a reduced physiological cost (3.2 METS), or a moderate level of energy expenditure. Use of a vacuum hoist resulted in a 39% reduction in the peak compressive load on the worker’s spine compared to manual lifting when palletizing 75-lb bags.