Department of Industrial and Systems Engineering, Virginia Tech, Blacksburg, VA 24061, USA.
Ergonomics. 2013;56(6):954-63. doi: 10.1080/00140139.2013.785601. Epub 2013 Apr 16.
Repetitive lifting is associated with an increased risk of occupational low back disorders, yet potential adverse effects of such exposure on trunk mechanical and neuromuscular behaviours were not well described. Here, 12 participants, gender balanced, completed 40 min of repetitive lifting in all combinations of three flexion angles (33, 66, and 100% of each participant's full flexion angle) and two lift rates (2 and 4 lifts/min). Trunk behaviours were obtained pre- and post-exposure and during recovery using sudden perturbations. Intrinsic trunk stiffness and reflexive responses were compromised after lifting exposures, with larger decreases in stiffness and reflexive force caused by larger flexion angles, which also delayed reflexive responses. Consistent effects of lift rate were not found. Except for reflex delay no measures returned to pre-exposure values after 20 min of recovery. Simultaneous changes in both trunk stiffness and neuromuscular behaviours may impose an increased risk of trunk instability and low back injury.
An elevated risk of low back disorders is attributed to repetitive lifting. Here, the effects of flexion angle and lift rate on trunk mechanical and neuromuscular behaviours were investigated. Increasing flexion angle had adverse effects on these outcomes, although lift rate had inconsistent effects and recovery time was more than 20 min.
重复性举重与职业性下腰痛风险增加相关，但这种暴露对躯干机械和神经肌肉行为的潜在不良影响尚未得到很好描述。本研究旨在全面研究三种屈伸角度（每个参与者全屈伸角度的 33%、66%和 100%）和两种举升速度（2 和 4 次/min）组合下，12 名性别均衡的参与者重复举重 40 分钟对躯干行为的影响。使用突发扰动在暴露前后和恢复期间获得躯干行为。结果：暴露后，躯干固有刚度和反射性反应受损，较大的屈伸角度导致刚度和反射力下降更大，反射反应延迟。未发现升力速率的一致影响。除了反射延迟，在 20 分钟的恢复后，没有任何测量值恢复到暴露前的值。同时改变躯干刚度和神经肌肉行为可能会增加躯干不稳定和下腰痛的风险。
重复性举重会增加下腰痛的风险。本研究旨在探讨屈伸角度和举升速度对躯干力学和神经肌肉行为的影响。增加屈伸角度对这些结果有不良影响，尽管举升速度的影响不一致，而且恢复时间超过 20 分钟。
