Effect of the cervical flexion angle during smart phone use on muscle fatigue of the cervical erector spinae and upper trapezius

Abstract

[Purpose] The purpose of this study was to examine the influence of the cervical flexion angle when using a smart phone on muscle fatigue of the cervical erector spinae (CES) and upper trapezius (UT). [Subjects] This study recruited 12 healthy adults. [Methods] Each subject sat on a chair, with his/her back against the wall and held a smart phone with both hands. Fatigue of the neck and shoulder muscles at different cervical flexion angles (0°, 30°, and 50°) was measured by electromyography. The following muscles were assessed: the right upper trapezius (RtUT), left upper trapezius (LtUT), right cervical erector spinae (RtCES), and left cervical erector spinae (LtCES). A cervical range of motion instrument was attached to the subjects’ heads to measure the cervical angle during the experiment. [Results] The RtUT and LtUT showed the highest muscle fatigue at a cervical flexion angle of 50° and the lowest fatigue at an angle of 30°. There was no significant difference in the muscle fatigue of the RtCES and LtCES at any of the cervical flexion angles. [Conclusion] UT muscle fatigue depends on the cervical flexion angle when using a smart phone.

The Effect of Visual Feedback of Head Angles With Using a Mobile Posture-Aware System on Craniocervical Angle and Neck and Shoulder Muscles Fatigue During Watching the Smartphone

“…And, they claimed that the craniocervical flexion angle should be maintained at 30° rather than 50° or 0°. 23 The other study reported that UT muscle activity was also significantly decreased with increasing of craniocervical angle correction by taping during computer work. 8 These previous studies indicate that the degree of fatigue of UT is affected by the angle of the neck and the angle of the arm.…”

“…Other previous study presented that higher shoulder flexion would increase risk of UT muscle activity level. 22 However, Lee et al 23 reported that the muscle fatigue of bilateral UT were highest at a cervical flexion angle of 50°…”

Shear wave elastography of the upper trapezius muscle in patient with chronic neck pain: is there a correlation between elastic modulus and intensity of pain?

“…Lee et al studied the relationship between activity of the upper trapezius and posture when a using smart phone. They found the alterations of muscle by electromyography (EMG) during cervical exion: The fatigue of the upper trapezius was − 0.2 ± 1.3 Hz at 0° neck exion and increased to − 3.5 ± 5.6 Hz at 50° [16]. Furthermore, for people with overhead work, the pressure-pain threshold of the upper trapezius was decreased by 1.4 lb after overhead work, which it veri ed that the ability of tolerance of pain was reduced when people had neck pain 35 .…”

“…People in certain professions such as computer and o ce workers have a higher risk of suffering from CNP. They usually sit for long periods with neck exion at a xed angle, which easily leads to discomfort and alteration of muscle fatigue [15][16]. The upper trapezius spanning the neck and shoulder is prone to structural muscle imbalance in poor posture.…”

Preventive effects of stretching and stabilization exercises on muscle fatigue in mobile phone users

“…Adult mobile phone usage was found to be one of the most important means of communication in an international study in 20071 ) . The rapid increase in the frequency of use of mobile phones among adults can adversely affect various aspects of human health, and numerous studies2,3,4 ) have investigated such adverse effects, particularly those focused on the neck and arms.…”