Abstract
A repeated measures factorial design was employed to investigate the effects of technique, height, distance and load moment on electromyographic (EMG) mean amplitude (average effort) and EMG area (total effort) during standing lifting tasks. Another experiment with repeated measures on all factors was used to study the effects of direction of box movement and load moment on EMG mean amplitude and EMG area during seated lifting tasks. Thirty males and thirty females performed all combinations of standing and seated lifts while the EMG activity of the sacrospinalis, glutei and hamstrings was recorded. For standing tasks, the main effects of load moment, height, distance and technique were significant for both EMG mean and EMG area for both sexes, the exceptions being the sacrospinalis mean activity for males, and the EMG areas for the glutei and hamstrings of females, which only approached significance. In seated lifting tasks, load moment had significant effects on all EMG means and areas for both sexes. Direction of box movement did not, in most cases, have a significant effect upon the dependent variables. Findings are discussed as they relate to the design and analysis of manual materials handling tasks. (Contract No 099-74-0057)
Source Name
Physiology and Ergonomics Branch, NIOSH, Cincinnati, Ohio
