Le Peter, Weisenbach Charles A, Mills Emily H L, Monforton Lanie, Kinney Micah J
Naval Medical Research Unit Dayton, Ohio, USA.
Oak Ridge Institute for Science and Education, Tennessee, USA.
Hum Factors. 2023 May;65(3):365-381. doi: 10.1177/00187208211019154. Epub 2021 Jun 2.
Assess neck muscle activity for varying interactions between helmet, posture, and visual stress in a simulated "helo-hunch" posture.
Military aviators frequently report neck pain (NP). Risk factors for NP include head-supported mass, awkward postures, and mental workload. Interactions between these factors could induce constant low-level muscle activation during helicopter flight and better explain instances of NP.
Interactions between physical loading (helmet doffed/donned), posture (symmetric/asymmetric), and visual stress (low/high contrast) were studied through neck muscle electromyography (EMG), head kinematics, subjective discomfort, perceived workload, and task performance. Subjects ( = 16) performed eight 30-min test conditions (varied physical loading, posture, and visual stress) while performing a simple task in a simulated "helo-hunch" seating environment.
Conditions with a helmet donned had fewer EMG median frequency cycles (which infer motor unit rotation for rest/recovery, where more cycles are better) in the left cervical extensor and left sternocleidomastoid. Asymmetric posture (to the right) resulted in higher normalized EMG activity in the right cervical extensor and left sternocleidomastoid and resulted in less lateral bending compared with neutral across all conditions. Conditions with high visual stress also resulted in fewer EMG cycles in the right cervical extensor.
A complex interaction exists between the physical load of the helmet, postural stress from awkward postures, and visual stress within a simulated "helo-hunch" seating environment.
These results provide insight into how visual factors influence biomechanical loading. Such insights may assist future studies in designing short-term administrative controls and long-term engineering controls.
在模拟“直升机弯腰”姿势下，评估头盔、姿势和视觉压力之间不同相互作用时的颈部肌肉活动。
军事飞行员经常报告颈部疼痛（NP）。NP的风险因素包括头部支撑重量、不良姿势和心理负荷。这些因素之间的相互作用可能在直升机飞行期间诱发持续的低水平肌肉激活，并能更好地解释NP的发生情况。
通过颈部肌肉肌电图（EMG）、头部运动学、主观不适、感知负荷和任务表现，研究了身体负荷（摘下/戴上头盔）、姿势（对称/不对称）和视觉压力（低/高对比度）之间的相互作用。16名受试者在模拟“直升机弯腰”座位环境中执行一项简单任务时，进行了8种30分钟的测试条件（不同的身体负荷、姿势和视觉压力）。
佩戴头盔的条件下，左颈伸肌和左胸锁乳突肌的EMG中位频率周期较少（这意味着运动单位的休息/恢复旋转，周期越多越好）。与中立姿势相比，不对称姿势（向右侧）导致右颈伸肌和左胸锁乳突肌的标准化EMG活动更高，并且在所有条件下侧弯更少。高视觉压力条件下，右颈伸肌的EMG周期也更少。
在模拟“直升机弯腰”座位环境中，头盔的物理负荷、不良姿势的姿势压力和视觉压力之间存在复杂的相互作用。
这些结果为视觉因素如何影响生物力学负荷提供了见解。这些见解可能有助于未来设计短期行政控制和长期工程控制的研究。
