School of Physical Therapy, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand.
Research Center in Back, Neck, Other Joint Pain and Human Performance (BNOJPH), Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, Thailand.
Ergonomics. 2021 Jul;64(7):900-911. doi: 10.1080/00140139.2021.1873423. Epub 2021 Jan 21.
This study compares the effects of different neck flexion angles on neck gravitational moment and muscle activity of users that stand and operate a smartphone. Thirty-two healthy young adult smartphone users performed texting tasks for three minutes at four different neck flexion angles (0°, 15°, 30°, and 45°) while standing. Neck gravitational moment and cervical erector spinae (CES) and upper trapezius (UT) activity were investigated. When the neck flexion angle increased, the gravitational moment of the neck increased significantly. The muscle activity of CES significantly increased when the neck flexion angle increased, whereas that of UT decreased. The lowest gravitational moment of the neck at 0° flexion was consistent with the lowest CES muscle activity and the lowest neck discomfort score. In conclusion, for texting while standing, adults should maintain their neck posture at 0° flexion to reduce the gravitational force acting on the cervical spine and alleviate neck discomfort. During smartphone use when standing, excessive neck flexion (30° and 45° flexion) should be avoided. The suggested neck posture when operating a smartphone while standing is 0° flexion. CES: cervical erector spinae; UT: upper trapezius; COG: centre of gravity; MSDs: musculoskeletal disorders; CROM: cervical range of motion; sEMG: surface electromyography; VAS: visual analogue scale; MVCs: maximum voluntary contractions.
本研究比较了不同颈部前屈角度对站立位操作智能手机的使用者颈部重力矩和肌肉活动的影响。32 名健康的年轻成年智能手机使用者在站立位下，分别以 0°、15°、30°和 45°四个不同的颈部前屈角度进行了三分钟的短信输入任务。研究了颈部重力矩以及颈伸肌（CES）和上斜方肌（UT）的活动。当颈部前屈角度增加时，颈部重力矩显著增加。随着颈部前屈角度的增加，CES 的肌肉活动显著增加，而 UT 的肌肉活动则减少。0°前屈时颈部的最小重力矩与 CES 肌肉活动的最小和颈部不适评分的最小一致。总之，对于站立位发短信，成年人应将颈部姿势保持在 0°前屈，以减少颈椎所受的重力，减轻颈部不适。在站立位使用智能手机时，应避免过度的颈部前屈（30°和 45°前屈）。建议站立位操作智能手机时的颈部姿势为 0°前屈。CES：颈伸肌；UT：上斜方肌；COG：重心；MSDs：肌肉骨骼疾病；CROM：颈椎活动度；sEMG：表面肌电图；VAS：视觉模拟评分；MVCs：最大随意收缩。
