The Ergonomics Laboratory, Department of Industrial and Manufacturing Systems Engineering, Iowa State University, Ames, IA 50011-2164, USA.
Ergonomics. 2010 Aug;53(8):1024-32. doi: 10.1080/00140139.2010.493957.
Lifting loads that have a horizontal velocity (e.g. lifting from a conveyor) is often seen in industry and it was hypothesised that the inertial characteristics of these loads may influence lifting technique and low back stress. Seventeen male participants were asked to perform lifting tasks under conditions of four horizontal load speeds (0 m/s, 0.7 m/s, 1.3 m/s and 2.4 m/s) and two lifting frequencies (10 and 20 lifts/min) while trunk motions and trunk muscle activation levels were monitored. Results revealed that increasing horizontal load speed from 0 m/s to 2.4 m/s resulted in an increase in peak sagittal angle (73 degrees vs. 81 degrees ) but lower levels of peak sagittal plane angular acceleration (480 degrees /s(2) vs. 420 [corrected] degrees /s(2)) and peak transverse plane angular acceleration (200 degrees /s per s vs. 140 degrees /s per s) and a consistent increase in trunk muscle co-activation. Participants used the inertia of the load to reduce the peak dynamics of the lifting motion at a cost of increased trunk flexion and higher muscle activity. STATEMENT OF RELEVANCE: Conveyors are ubiquitous in industry and understanding the effects of horizontal load speed on the lifting motions performed by workers lifting items from these conveyors may provide some insight into low back injury risk posed by these tasks.
从传送带上提起具有水平速度的负载（例如从传送带上提起）在工业中很常见，有人假设这些负载的惯性特征可能会影响举重技术和腰部压力。研究人员要求 17 名男性参与者在四种水平负载速度（0 m/s、0.7 m/s、1.3 m/s 和 2.4 m/s）和两种举重频率（10 次/分钟和 20 次/分钟）下进行举重任务，同时监测躯干运动和躯干肌肉激活水平。结果表明，水平负载速度从 0 m/s 增加到 2.4 m/s 会导致峰值矢状角增加（73 度对 81 度），但峰值矢状面角加速度（480 度/s²对 420 [校正]度/s²）和峰值横平面角加速度（200 度/s/s 对 140 度/s/s）降低，躯干肌肉协同激活增加。参与者利用负载的惯性来降低举重运动的峰值动态，代价是增加躯干弯曲和更高的肌肉活动。相关性声明：输送机在工业中无处不在，了解水平负载速度对工人从这些输送机上提起物品时的举重动作的影响，可能有助于了解这些任务对腰部受伤的风险。
