Mining Publication: Effects of Lifting in Four Restricted Postures

The purpose of this study was to examine the lifting capacity of low-seam coal miners in four restricted work postures (roof heights of 36", 40", 44", and 48"), investigate the associated metabolic costs, and to examine electromyographic (EMG) data from eight trunk muscles during the lifting procedure. Subjects were thirteen underground miners accustomed to handling materials in restricted work postures. Each subject performed two twenty-minute periods of asymmetric lifting in each of four postures during the day of testing. The frequency of lifting was 10 lifts per minute. A specially designed lifting box incorporated microswitches in one handle of the box and another in the bottom of the box, in order to examine the trunk muscle function at specific points during the lifting cycle. The data collected will be used by the Bureau of Mines to make recommendations for lifting materials in low-seam coal mines.