Effects of a standing aid on loads on low back and legs during dishwashing.

In order to prevent low back pain during dishwashing, we developed a standing aid for supporting the forward bending posture, and then evaluated the effects of the standing aid on decreasing load on the low back and legs. Eight female volunteers were asked to wash plates for 60 minutes in each of three working postures: (a) without the standing aid, (b) with the standing aid under the thighs, and (c) with the standing aid under the shins. The following were measured: electromyogram (EMG), electrocardiogram (ECG), the force applied to the standing aid, the ground reaction force, the bending angle of the trunk, the bending angle of the knee, and local discomfort in body regions. While using the standing aid under the shins, the muscle load decreased in the low back and legs. While using the standing aid under the thighs, the muscle loads decreased in the low back but increased in the legs. It was suggested that the standing aid under the shins was more effective in decreasing the load on the low back and legs than the standing aid under the thighs.