Influences of the position of the head on posture while lifting.

In clinical training of some lower back pain patients, teaching them to control their lumbar lordosis during lifting may be difficult. Therefore, another effective method for lifting technique is required. In standing, head cannot move without some compensating postural adjustment. The purpose of this study was to examine the influence of head position on lifting posture. Fourteen healthy male volunteers (22.6 +/- 4.4 years old) lifted a case while maintaining two different head positions; a downward position and an upright position. In the upright position, activities of the latissimus dorsi and vastus lateralis significantly increased, and these of the biceps femoris significantly decreased during the initial 100 msec phase of lifting. There were no differences in the activities of the upper trapezius, lumbar extensor muscles (L3, L5), and obliquus abdominis under the two conditions. There were also no differences in the lumbar angle when the case was lifted. The flexion angles of the hip, knee, and ankle significantly increased, and the lumbar spine moved closer to the case. Lifting posture was influenced by the head position. Advantages included being able to shift loads on the body from the lower back to the legs, to move the lumbar spine closer to the case, and to relatively increase the moment of lumbar extension. The weight of the head as it moved upward and back, and the weight of the rear part of the body as it moved downward and forward helped to maintain balance.