Faculty of Physical Therapy, Mahidol University, Salaya, Nakhon Pathom, Thailand.
Department of Biomedical Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, United States of America.
PLoS One. 2023 Mar 23;18(3):e0283521. doi: 10.1371/journal.pone.0283521. eCollection 2023.
Although young adults regularly perform tablet writing, biomechanics during the tablet writing with different tilt angles has not been studied. The objective of this study was to compare posture, muscle activity, and discomfort at the neck and shoulder between tablet writing with 0° (horizontal) and 30° tablet tilt angles over 40 minutes in healthy young adults.
Twenty participants wrote continuously for 40 minutes on a tablet with both tilt angles in a randomized order. Between conditions, there was a 5-minute activity break. Differences in neck and shoulder posture, muscle activity, and discomfort between both tablet tilt angles and changes in the outcomes every 10 minutes over 40 minutes were investigated.
With the tilted tablet, there were lower neck flexion (Z = -4.637, P<0.001), lower shoulder extension (Z = -3.734, P<0.001), and lower neck Visual Analogue Scale (VAS) (left; Z = -4.699, P<0.001 and right; Z = -3.874, P<0.001) as compared to the no tilt condition. However, the right upper trapezius muscle activity was higher in the tilted condition as compared to the no tilt one. Over 40 minutes, the neck VAS (left; χ2(4) = 30.235, P<0.001 and right; χ2(4) = 32.560, P<0.001) and heart rate variability (χ2(4) = 12.906, P = 0.012) showed notable increases after 20 minutes compared to baseline.
In conclusion, adjusting the tablet tilt to 30° and limiting time spent to 20 minutes are recommended for young adults during the tablet writing to prevent neck problems.
尽管年轻人经常进行平板电脑书写，但不同倾斜角度下的平板电脑书写生物力学尚未得到研究。本研究的目的是比较健康年轻人在平板电脑上以 0°（水平）和 30°倾斜角度进行 40 分钟平板电脑书写时的姿势、肌肉活动和颈部及肩部不适。
20 名参与者以随机顺序在两种倾斜角度下连续 40 分钟在平板电脑上书写。两种条件之间有 5 分钟的活动休息时间。研究了两种平板电脑倾斜角度之间的颈部和肩部姿势、肌肉活动和不适的差异，以及 40 分钟内每 10 分钟的结果变化。
与无倾斜状态相比，使用倾斜平板电脑时，颈部屈曲（Z = -4.637，P<0.001）、肩部伸展（Z = -3.734，P<0.001）和颈部视觉模拟量表（VAS）（左侧；Z = -4.699，P<0.001 和右侧；Z = -3.874，P<0.001）更低。然而，与无倾斜状态相比，右侧上斜方肌的肌肉活动在倾斜状态下更高。在 40 分钟内，与基线相比，颈部 VAS（左侧；χ2(4) = 30.235，P<0.001 和右侧；χ2(4) = 32.560，P<0.001）和心率变异性（χ2(4) = 12.906，P = 0.012）在 20 分钟后显示出明显的增加。
总之，建议年轻人在平板电脑书写时将平板电脑倾斜度调整至 30°并限制使用时间至 20 分钟，以预防颈部问题。
