Differences in neck muscle activity according to lying positions using a smartphone.

Area of Science:

• Ergonomics
• Biomechanics
• Digital Health

Background:

• Increased smartphone usage leads to prolonged device interaction in recumbent postures.
• Understanding the ergonomic implications of smartphone use in various lying positions is crucial for public health.

Purpose of the Study:

• To investigate and compare neck muscle activity during smartphone use in four distinct lying positions.
• To identify the optimal lying posture for minimizing neck muscle strain.

Main Methods:

• Electromyography (EMG) was used to assess activity in key neck muscles (SCM, anterior scalene, CES, UT).
• Muscle activity was measured in 23 healthy volunteers across supine, prone on elbows, side lying, and 45-degree head-turned side lying positions.

Main Results:

• Significant differences in sternocleidomastoid (SCM) and cervical erector spinae (CES) activity were observed across positions.
• Greater SCM asymmetry occurred in the 45-degree head-turned side lying position.
• Increased CES and upper trapezius (UT) asymmetry was noted in side lying positions.

Conclusions:

• The supine position demonstrated the lowest neck muscle activity and asymmetry.
• Adopting a supine posture while using a smartphone may effectively reduce neck muscle activation and associated strain.