Abstract
The purpose of this study is to clarify the relationship between whole body posture and types of pushing task. We evaluated whole body posture and physical workload on various body parts for each pushing condition. There were 12 total experimental conditions and the materials handled were arranged for each pushing condition. The types of pushing task were set at two different levels (instantaneous and continuous). The pushing direction was set at two different levels (forward and downward). The height of the material was set at three different levels (knee, waist and shoulder). The result showed that the effect of the types of pushing task was greater at knee height than waist and shoulder heights. In the continuous task at knee height, subjects tend ed to take a squat posture during forward pushing task unlike that in the instantaneous task. Under the same condition, subjects flexed knee joint and then inclined the upper-body trunk. The relationship between whole body posture and pushing direction was not clear; however, the relationship between pushing direction and physical workload was clearly shown. The result showed that lower back compression was high during downward pushing, and the elbow and shoulder joint torque was high during forward pushing. At shoulder height, subjects tended to push using upper limb movement without trunk inclination and knee flexion. At knee height, subjects took a squatting or forward-bending posture. The pushing force was higher at knee height than shoulder height. In the instantaneous task, the pushing force was higher than that in continuous task by 20 N, and the lower back compression and upper limb joint torque was greater than that during continuous pushing.
