Workload evaluation under unstable floor conditions

本研究的目的是客观地评估不稳定站立条件下的工作负荷。实验结果如下：1）当被试者在光滑的地板上行走时，被试者会改变他们的姿势以减少所需的摩擦系数。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，受试者感觉大腿负荷低于小腿负荷。防滑安全鞋能有效地降低肌肉活动。2）在湿滑地面上搬运行李时，肌肉活动随行李重量的增加而增加。足部压力测量表明，当地板湿滑时，施加到脚尖的力的比率增加。上半身的主观抱怨主要受行李的大小和重量的影响，而腿部的主观抱怨主要受地板条件的影响。3）为了检验倾斜地板的影响，在从前向后和从一侧到另一侧倾斜的地板上进行安静的站立任务和步行任务。当梯度增加时，两项任务的肌电图活动都增加了。此外，当受试者在横向倾斜的地板上时，肌电图活动高于向上或向下倾斜的地板。当梯度增加时，消耗的能量增加。向上倾斜的地板上的主观抱怨较高，而在侧向倾斜的地板上安静站立的受试者的主观抱怨较低。4）根据这两组实验数据，建立了根据肌肉活动和能量消耗来评估不稳定条件下的工作负荷的表达式。

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.