Kinematic evaluation of two snow-shovel designs

摘要

The objective of this study was to determine how different shovel designs affect trunk motion during snow shoveling. A shovel having a straight shaft and a shovel having a bent shaft were evaluated across three levels of task asymmetry. The primary dependent variables were measures of lumbar kinematics in three directions with respect to the spine (sagittal, rotational, and frontal) recorded with a lumbar motion monitor. Ratings of perceived discomfort and measures of heart rate were also collected. In a laboratory experiment, 12 participants were required to stimulate snow shoveling in three different directions with each shovel. Results showed that the bent shovel significantly' reduced the lumbar velocity and acceleration in the sagittal plane without affecting motion in the rotational or frontal planes. Most sagittal and rotational motion parameters increased significantly as throwing direction became more asymmetric. The discomfort ratings indicated that the low back, arms, and wrist were the body regions most severely affected by the task, with some evidence of differences between the two shovel designs.