Disturbance and recovery of trunk mechanical and neuromuscular behaviours following repetitive lifting: influences of flexion angle and lift rate on creep-induced effects

作者：Toosizadeh Nima; Bazrgari Babak; Hendershot Brad; Muslim Khoirul; Nus**aum Maury A^*; Madigan Michael L

来源：Ergonomics, 2013, 56(6): 954-963.

DOI：10.1080/00140139.2013.785601

• low back pain
• lifting
• trunk flexion
• stiffness
• reflex
• biomechanics

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 40min of repetitive lifting in all combinations of three flexion angles (33, 66, and 100% of each participant%26apos;s full flexion angle) and two lift rates (2 and 4lifts/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 20min of recovery. Simultaneous changes in both trunk stiffness and neuromuscular behaviours may impose an increased risk of trunk instability and low back injury. %26lt;br%26gt;Practitioner summary 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 20min.

• 出版日期2013-6-1
• 单位美国弗吉尼亚理工大学(Virginia Tech)