Discomfort
The 30° tablet tilt angle could reduce neck discomfort compared to the other tilt angle; however, this was inconsistent with the previous study that VAS discomfort was not significantly different between tablet tilt angles [Shoulder discomfort did not alter between either tablet tilt angles or time intervals. This was consistent with the study of Chiu et al. which found similar shoulder comfort among tablet tilt angles [For HRV, the LF/HF showed no significant difference between tablet tilt angles. This finding was inconsistent with the studies of Le and Marras [Over 40 minutes, the LF/HF showed notable increases from the baseline at 20 minutes which was consistent with the result of neck VAS. However, there was no change of LF/HF over 40 minutes of writing. This was consistent with the study of Weston et al. [Overall, tablet users had less neck flexion and shoulder extension during writing on the tablet with a 30° tilt angle as compared to no tilt angle. With less neck flexion, neck discomfort will be reduced due to decreased load on the cervical spine. Moreover, lower neck flexion at the tilted tablet should have reduce UT and CES muscle activity as in previous studies [