Division of Safety Research, National Institute for Occupational Safety and Health, 1095 Willowdale Rd., Morgantown, WV 26505, USA.
Appl Ergon. 2011 Jul;42(5):672-81. doi: 10.1016/j.apergo.2010.10.002. Epub 2010 Nov 11.
The risk of falls from height on a construction site increases under conditions which degrade workers' postural control. At elevation, workers depend heavily on sensory information from their feet to maintain balance. The study tested two hypotheses: "sensory enhancement"--sub-sensory (undetectable) random mechanical vibrations at the plantar surface of the feet can improve worker's balance at elevation; and "sensory suppression"--supra-sensory (detectable) random mechanical vibrations can have a degrading effect on balance in the same experimental settings. Six young (age 20-35) and six aging (age 45-60) construction workers were tested while standing in standard and semi-tandem postures on instrumented gel insoles. The insoles applied sub- or supra-sensory levels of random mechanical vibrations to the feet. The tests were conducted in a surround-screen virtual reality system, which simulated a narrow plank at elevation on a construction site. Upper body kinematics was assessed with a motion-measurement system. Postural stability effects were evaluated by conventional and statistical mechanics sway measures, as well as trunk angular displacement parameters. Analysis of variance did not confirm the "sensory enhancement" hypothesis, but provided evidence for the "sensory suppression" hypothesis. The supra-sensory vibration had a destabilizing effect, which was considerably stronger in the semi-tandem posture and affected most of the sway variables. Sensory suppression associated with elevated vibration levels on a construction site may increase the danger of losing balance. Construction workers at elevation, e.g., on a beam or narrow plank might be at increased risk of fall if they can detect vibrations under their feet. To reduce the possibility of losing balance, mechanical vibration to supporting structures used as walking/working surfaces should be minimized when performing construction tasks at elevation.
建筑工地高处坠落的风险在降低工人姿势控制能力的情况下会增加。在高处，工人主要依靠脚部的感觉信息来保持平衡。该研究检验了两个假设：“感觉增强”——脚部足底表面的亚感觉（无法检测到的）随机机械振动可以提高工人在高处的平衡能力；和“感觉抑制”——超感觉（可检测到的）随机机械振动在相同的实验环境中会对平衡产生不利影响。六名年轻（20-35 岁）和六名年老（45-60 岁）建筑工人在仪器化凝胶鞋垫上以标准和半并脚姿势站立时进行了测试。鞋垫向脚部施加亚感觉或超感觉水平的随机机械振动。测试在模拟建筑工地高处狭窄木板的环绕屏幕虚拟现实系统中进行。使用运动测量系统评估上半身运动学。通过传统和统计力学摆动测量以及躯干角位移参数评估姿势稳定性效果。方差分析没有证实“感觉增强”假设，但为“感觉抑制”假设提供了证据。超感觉振动具有不稳定性作用，在半并脚姿势下更为明显，并且影响了大部分摆动变量。与建筑工地高振动水平相关的感觉抑制可能会增加失去平衡的危险。在高处作业的建筑工人，例如在梁或狭窄木板上，可能会因脚下能感觉到振动而增加摔倒的风险。为了降低失去平衡的可能性，在高处进行施工任务时，应尽量减少用作行走/工作表面的支撑结构的机械振动。
