Exploring the effects of task design on the flexion-relaxation phenomenon in the lumbar spine during repetitive lifting
研究了重复举重任务中，不同负荷和重复次数组合对腰椎屈曲-放松角度变化的影响，发现男性在低负荷高重复条件下、女性在高负荷低重复条件下屈曲-放松起始角增加，提示任务设计对腰椎的影响存在性别差异。
Repetitive forward flexion of the lumbar spine can result in creep deformation which can disrupt load sharing between active and passive tissues. Lumbar spine kinematics and lumbar erector spinae (LES) electromyography were used to measure flexion relaxation (FR) angle changes across two lifting conditions matched for cumulative external load (Condition 1: 75 lifts of 13 kg load, Condition 2: 150 lifts of 6.5 kg load). Males showed increases in FR onset angle in response to the low load, high repetition condition, while females displayed increases in these metrics in the high load, low repetition condition. This work suggests that task design of a repetitive lifting task, and creep accumulation in the lumbar spine may be sex specific and future work should look to consider both task parameters, as well as worker demographics when designing and evaluating repetitive lifting task.