Richter H O, Zetterberg C, Forsman M
Department of Occupational and Public Health Sciences, Faculty of Health and Occupational Studies, Centre for Musculoskeletal Research, University of Gävle, 801 76, Gävle, Sweden,
Eur J Appl Physiol. 2015 Jul;115(7):1501-12. doi: 10.1007/s00421-015-3125-9. Epub 2015 Feb 20.
To investigate if trapezius muscle activity increases over time during visually demanding near work.
The vision task consisted of sustained focusing on a contrast-varying black and white Gabor grating. Sixty-six participants with a median age of 38 (range 19-47) fixated the grating from a distance of 65 cm (1.5 D) during four counterbalanced 7-min periods: binocularly through -3.5 D lenses, and monocularly through -3.5 D, 0 D and +3.5 D. Accommodation, heart rate variability and trapezius muscle activity were recorded in parallel.
General estimating equation analyses showed that trapezius muscle activity increased significantly over time in all four lens conditions. A concurrent effect of accommodation response on trapezius muscle activity was observed with the minus lenses irrespective of whether incongruence between accommodation and convergence was present or not.
Trapezius muscle activity increased significantly over time during the near work task. The increase in muscle activity over time may be caused by an increased need of mental effort and visual attention to maintain performance during the visual tasks to counteract mental fatigue.
研究在视觉要求较高的近距工作过程中，斜方肌活动是否会随时间增加。
视觉任务包括持续注视一个对比度变化的黑白Gabor光栅。66名年龄中位数为38岁（范围19 - 47岁）的参与者在四个平衡的7分钟时间段内，从65厘米（1.5 D）的距离注视光栅：通过-3.5 D镜片双眼注视，以及通过-3.5 D、0 D和+3.5 D镜片单眼注视。同时记录调节、心率变异性和斜方肌活动。
广义估计方程分析表明，在所有四种镜片条件下，斜方肌活动均随时间显著增加。无论调节与集合之间是否存在不一致，使用负镜片时均观察到调节反应对斜方肌活动的并发效应。
在近距工作任务期间，斜方肌活动随时间显著增加。随着时间推移肌肉活动的增加可能是由于在视觉任务中为维持表现以对抗精神疲劳而对精神努力和视觉注意力的需求增加所致。
