Workload evaluation under unstable floor conditions

本研究的目的是客观评估不稳定站立状态下的工作量。得到了以下结果：1)当受试者在光滑的地板上行走时，受试者改变姿势以减小所需的摩擦系数。然而，下肢的肌肉共同收缩，肌肉活动整体上升。对下肢负荷的主观评价显示，受试者感觉上肢负荷低于下肢负荷。此外，防滑安全鞋可以有效地减少肌肉活动。2)在湿滑的地板上搬运行李时，随着行李变得更重、更大，肌肉活动趋于上升。足部压力测量表明，当地面湿滑时，施加在脚尖上的力的比例会增加。关于上半身的主观抱怨主要受行李大小和重量的影响，而腿部的主观抱怨主要受地板条件的影响。3)为了考察倾斜地板的影响，在前后倾斜和左右倾斜的地板上进行安静站立任务和步行任务。当梯度增加时，两种任务的肌电图活动都有所增加。此外，当受试者在倾斜的地板上时，他们的肌电图活动比在倾斜的地板上或倾斜的地板上时要高。当梯度增大时，所消耗的能量增大。向上倾斜楼层的主观抱怨率较高，横向倾斜楼层安静站立的主观抱怨率低于其他楼层。4)根据这两组实验数据，建立了不稳定状态下肌肉活动和能量消耗的负荷评估表达式。

The purpose of this study was to objectively evaluate the workload on an unstable standing condition. The following results were obtained.1)When subjects walk on a slippery floor, the subjects changed their postures to reduce the required coefficient of friction. However, the muscles of the lower limbs co-contract and muscle activity rises overall. A subjective evaluation of the load on the lower limbs revealed that subjects feel the load at upper leg was lower than those at lower leg. Moreover, the antiskid safety shoes were effective to reduce the muscle activity.2)At the luggage carrying task on a slippery floor, muscle activity tended to rise as the luggage became heavier and bigger. Foot pressure measurement has shown that the ratio of the force applied to the tiptoe increases when the floor is slippery. The subjective complaints concerning the upper body were affected mainly by the size and weight of the luggage, whereas those of the legs were affected mainly by the floor conditions.3)To examine the influence of an inclined floor, a quiet standing task and foot-stepping task were conducted on a floor that inclined from front to back and from side to side. Electromyogram activity rose during both tasks when the gradient increased. Moreover, electromyogram activity was higher when subjects were on a laterally inclined floor than when they were on an upwardly or downwardly inclined floor. When the gradient increases, the energy consumed increases. The subjective complaint on the upwardly inclined floor was high, and that by subjects in quiet standing on the laterally inclined floor was lower than the other floor condition.4)An expression to evaluate workload at an unstable condition according to both muscle activity and energy consumption was made based on these two sets of experimental data.