Electromyographic analysis of upper trapezius, abductor pollicis longus and abductor pollicis brevis during smartphone use in different positions among young male and female subjects.

Background: Smartphone use has increased tremendously in recent times and there are various adverse musculoskeletal consequences associated with its use. Alteration in the activation patterns of muscles in certain positions may be the reason behind the development of musculoskeletal disorders in smartphone users; however, it has not been thoroughly investigated by the existing literature.

Objectives: To investigate the electromyographic (EMG) activity of upper trapezius (UT), abductor pollicis brevis (APB) and abductor pollicis longus (APL) during smartphone use in three different positions (standing, sitting on the chair and sitting cross legged on the floor) in young male versus female subjects.

Methods: Twenty-six young male (age: 23.77 ± 2.47 years) and 26 young female (age: 22.45 ± 2.32 years) smartphone users were recruited from Centre for Physiotherapy and Rehabilitation Sciences, Jamia Millia Islamia, New Delhi, India. EMG activity of UT, APB and APL muscles was examined using surface electrodes during a smartphone task in three different positions, i.e. standing, sitting on a chair, sitting cross-legged on the floor. The smartphone task consisted of typing English quotations for 20 s 3 times with a rest period of 10 s between each quotation and a 5-min interval between each position, respectively.

Results: EMG activity of the UT muscle was found to be significantly reduced when sitting on a chair as compared to standing (p < 0.001) and sitting cross-legged (p = 0.008) during smartphone use. APB and APL muscle activity were not significantly different between the three positions (p > 0.05). Moreover, the activation patterns of these muscles did not differ in male and female subjects (p > 0.05).

Conclusion: The present study demonstrates that the UT muscle is least activated when sitting on chair as compared to standing and sitting cross-legged during smartphone use. Moreover, the activity of neck and thumb muscles does not vary significantly between male and female subjects during smartphone use in different positions. As UT muscle activation significantly varies with the position of smartphone use, thus, the position adopted during smartphone use should be taken into consideration and the position which causes least strain on muscles, i.e. sitting on the chair should be adopted.