The effects of method of use, tool design, and roof height on trunk muscle activities during underground scaling bar use.

Epidemiologic studies have shown that the scaling bar, a hand tool used in underground mining, is frequently associated with the risk of back injury. An experiment was performed to investigate the effects of method of tool use, mine roof height, and tool design upon the activity of six trunk muscles and the ability to exert force with the bar. Roof height and scaling bar design had the largest effects on levels of muscle activation. Striking force did not differ significantly between tool designs. A biomechanical model was used to evaluate the collective effects of the trunk musculature activities upon spine loading. It was found that a significant reduction in predicted spine compression and shear forces can be achieved through the use of a counterbalanced scaling bar. The implications of these results are discussed. [ABSTRACT FROM PUBLISHER]