An examination of shoulder kinematics and kinetics when using a commercial trunk harness while sheep shearing

Sheep shearing is a very physically demanding occupation, especially on the low back, such that many commercial harnesses have been developed to help reduce the load on the back. Such harnesses have been shown to significantly reduce peak and cumulative low back loads; however, the effect that these harnesses have on the shoulders, which are also highly involved during sheep shearing, has not been previously examined. The purpose of this study was to examine the shoulder postures and cumulative shoulder moments of 12 New Zealand sheep shearers. The use of the trunk harness reduced the percentage of time spent in shoulder flexion greater than 90 degrees and the time spent in shoulder abduction greater than 45 degrees as well as reduced the cumulative net joint flexor, abductor, and adductor shoulder moments by a minimum of 21%, 14%, and 42%, respectively. Therefore, the use of a commercial trunk harness to reduce low back injury may also help to reduce the risk of shoulder injury while sheep shearing.