Lee P J, Granata K P
Musculoskeletal Biomechanics Laboratories, Department of Engineering Science and Mechanics, School of Biomedical Engineering and Science, Virginia Polytechnic Institute and State University, 219 Norris Hall (0219), Blacksburg, VA 24061, USA.
Ergonomics. 2006 Feb 22;49(3):235-48. doi: 10.1080/00140130500485285.
Handle or interface design can influence torso muscle recruitment and spinal load during pushing tasks. The objective of the study was to provide insight into the role of interface stability with regard to torso muscle recruitment and biomechanical loads on the spine. Fourteen subjects generated voluntary isometric trunk flexion force against a rigid interface and similar flexion exertions against an unstable interface, which simulated handle design in a cart pushing task. Normalized electromyographic (EMG) activity in the rectus abdominus, external oblique and internal oblique muscles increased with exertion effort. When using the unstable interface, EMG activity in the internal and external oblique muscle groups was greater than when using the rigid interface. Results agreed with trends from a biomechanical model implemented to predict the muscle activation necessary to generate isometric pushing forces and maintain spinal stability when using the two different interface designs. The co-contraction contributed to increased spinal load when using the unstable interface. It was concluded that handle or interface design and stability may influence spinal load and associated risk of musculoskeletal injury during manual materials tasks that involve pushing exertions.
在推的任务中，手柄或界面设计会影响躯干肌肉的募集和脊柱负荷。本研究的目的是深入了解界面稳定性在躯干肌肉募集和脊柱生物力学负荷方面的作用。14名受试者分别对着刚性界面产生自愿等长躯干屈曲力，并对着不稳定界面进行类似的屈曲用力，该不稳定界面模拟了推车任务中的手柄设计。随着用力程度增加，腹直肌、腹外斜肌和腹内斜肌的标准化肌电图（EMG）活动增强。使用不稳定界面时，腹内斜肌和腹外斜肌群的EMG活动大于使用刚性界面时。结果与为预测使用两种不同界面设计产生等长推力并维持脊柱稳定性所需的肌肉激活而实施的生物力学模型的趋势一致。使用不稳定界面时，协同收缩导致脊柱负荷增加。得出的结论是，在涉及推的用力的手工搬运任务中，手柄或界面设计及稳定性可能会影响脊柱负荷以及相关的肌肉骨骼损伤风险。
