Lin J-H, McGorry R W, Chang C-C, Dempsey P G
Liberty Mutual Research Institute for Safety, 71 Frankland Rd., Hopkinton, MA 01748, USA.
Ergonomics. 2007 Jun;50(6):859-76. doi: 10.1080/00140130701237618.
Powered hand tools produce reaction forces that may be associated with upper extremity musculoskeletal disorders. The handle displacement, grip force and upper limb muscle activity (electromyography (EMG)) due to the effects of operator experience, working height and distance, type of tool and fastener joint hardness were measured in this study with 15 experienced and 15 novice nutrunner users. The results show that when pistol grip handles were used to work on a horizontal surface, experienced users allowed an average handle displacement of 7.9 degrees, while novice users allowed 11.5 degrees. Average EMG scaled by reference voluntary contraction (RVC) at forearm flexors, forearm extensors and biceps were greater for experienced users (318% RVC, 285% RVC, 143% RVC, respectively) than for novice users (246% RVC, 219% RVC, 113% RVC, respectively). Experienced users exerted more grip force than novice users when using right angle handles, but less force when using pistol grip handles. The results suggest that it is possible to minimize tool handle displacement by adapting the workplace layout to permit different working postures for each user group.
电动手动工具会产生反作用力，这可能与上肢肌肉骨骼疾病有关。本研究对15名经验丰富的螺母拧紧器使用者和15名新手使用者，测量了由于操作者经验、工作高度和距离、工具类型以及紧固件接头硬度的影响而产生的手柄位移、握力和上肢肌肉活动（肌电图（EMG））。结果表明，当使用手枪式握把在水平面上作业时，经验丰富的使用者平均手柄位移为7.9度，而新手使用者为11.5度。经验丰富的使用者在前臂屈肌、前臂伸肌和二头肌处，经参考自主收缩（RVC）缩放后的平均肌电图，分别为318%RVC、285%RVC、143%RVC，高于新手使用者（分别为246%RVC、219%RVC、113%RVC）。经验丰富的使用者在使用直角手柄时比新手使用者施加的握力更大，但在使用手枪式握把时施加的力更小。结果表明，通过调整工作场所布局，为每个用户群体提供不同的工作姿势，有可能将工具手柄位移降至最低。
