Effect of reduced force requirements on neuromuscular inputs and movement patterns in manual materials handling tasks

起重是手工材料处理工作中最常见的任务之一，也是最常见的受伤原因。 机械离体提升辅助装置（即，起重机或手推车）减少了关节载荷并提高了效率，特别是在提升和移动重物以及操纵超出人类能力的笨拙物体时。 然而，当负载在人类提升能力范围内时，工人倾向于手动提升，因为大多数机械升降机和提升设备不能快速操作，并迫使工人减速。 虽然一种解决方案是制造更快的“离体”提升辅助装置，但另一种解决方案是设计“体上”提升辅助装置。 本申请的目的是检查一种新的动态“身体上”个人提升辅助装置（PLAD）对躯干和腿部肌肉活动以及脊柱上的力和力矩的安全性和有效性，以及在手动材料处理任务中产生的运动模式。 更具体地说，我特别感兴趣的是工人在佩戴动态辅助设备时如何举起重物，以及它是否是一种安全有效的设备。 为了实现这一目标，将进行四项研究。 第一项研究将检查无人体工程学移位辅助装置（无PLAD）和佩戴动态移位辅助装置（PLAD）对脊柱累积载荷的影响，包括：a）对L4/L5椎间盘累积力矩的影响; B）在振幅和频率域中处理的累积EMG; c）器械导致的技术变化; d）从举重开始到结束受试者之间举重技术的变化;以及，e）根据条件的主观和心率差异。 第二项研究将检查PLAD在静态保持和动态任务期间在不同躯干姿势角度和不同弹性元件张力下对躯干稳定性的影响。 在第三项研究中，将对男性和女性重复这些实验，以确定性别的差异效应。最后的研究将确定在工业环境中佩戴这种动态辅助设备超过八周是否会导致肌肉的去调节和/或运动模式的改变。

Lifting is the one of the most common tasks performed in manual materials handling jobs and is the most frequently reported cause of injury.  Mechanical off-body lifting aids (i.e., hoists or trolleys) reduce joint loading and increase efficiency, especially when lifting and moving heavy loads and manipulating awkward objects that are beyond human capability.   However, when loads are within human lifting capacity, there is a tendency for workers to lift manually since most mechanical hoists and lifting devices cannot be operated quickly and force workers to slow down.  Although one solution is to make faster 'off-body' lift assists, another solution is to design 'on-body' lifting assists.  The purpose of this application is to examine the safety and effectiveness of a new dynamic 'on-body' personal lift assistive device (PLAD) on the trunk and leg muscle activity and forces and moments on the spine and the resulting movement patterns in manual materials handling tasks.  More specifically, I am particularly interested in how workers lift loads when wearing a dynamic assistive device and whether it is a safe and effective device to use.  To accomplish this objective, there will be four studies.  The first study will examine the effects of no ergonomic lifting aid (no-PLAD) and wearing a dynamic lift assist (PLAD) on cumulative loading on the spine in terms of: a) the impact on cumulative moments at L4/L5 disc; b) cumulative EMG as processed in amplitude and frequency domains; c) changes to technique as a result of the device; d) changes in lifting technique between subjects from beginning to end of the lift; and, e) subjective and heart rate differences by condition.  The second study will examine the effect of the PLAD on trunk stability during both static holding and dynamic tasks at different trunk postural angles with different elastic element tensions.  In the third study, these experiments will be repeated for men and women to determine the differential effect of sex. The final study will determine if such a dynamic assistive device when worn over an eight week period in an industrial situation will cause de-conditioning of muscles and/or alterations in movement patterns.