Lifting strengths in different horizontal distances of objects to be lifted.

This study recruited eleven healthy males and thirteen healthy females to examine their maximum two-handed isometric back lifting strength, upper-body lifting strength, arm lifting strength and shoulder lifting strength in three different horizontal distances of objects to be lifted (toes were anterior to, aligned with, and posterior to the exerted handle). The results showed that human lifting strength decreased significantly as the toe position shifted from anterior of the vertical plane of the exerted handle to posterior of the vertical plane of the exerted handle. The strength order relationship between back lifting strength and upper-body lifting strength was dependent on the horizontal distance of objects to be lifted. This study also observed that the effects of the horizontal distance of objects to be lifted on human lifting postural angles for the four assessed lifting types mainly occurred in the upper extremities. This study recommends that practitioners should not overlook the effects of the horizontal distance of objects to be lifted on lifting strength when evaluating workers' lifting strength for screening purposes.