Model for analysis of weight lifting motion considering the abdominal pressure increased by Valsalva maneuver

This paper proposed the model to estimate the load on the lumber vertebra considering not only the value presumed from posture but also the increased amount by Valsalva maneuver of extrapolating from the vital capacity. The pressure force can be estimated to be reduced by about 30% by the effect of the abdominal pressure by using the proposed model as said so far. From the error of the presumed value of ground reaction force from an actual measurement, it is thought that the presumed accuracy of the lumbar vertebra load using the proposed model is smaller than 10%. Furthermore, two operations with extreme start-on posture were compared on transition of the compressive force and shear force on the lumbar vertebra. It was brought out that a start-on posture signficantly affects the maximum load on the lumber vertebra. The result suggests that optimal start-on posture may be between two postures.