BACKGROUND & AIM:​ The use of technology has become a global phenomenon and has changed how individuals socialize, work, play, and perform leisure activities. However, the use of technology can result in forward slumped head and neck postures and static muscle loading when used for long durations of time. This may cause or contribute to neck pain (NP) in healthy users and increase the severity of NP in subclinical NP users. The purposed of this thesis was to:​ 1) determine if slumped/flexed head and neck postures during long duration mobile device use will increase discomfort in both groups, or if a subclinical NP group would experience higher discomfort levels, and increased neck muscle activity and 2) examine if the subclinical NP group produces different cervical spine kinematics compared to healthy individuals.

METHODS:​ Eighteen UOIT students (10 healthy participants with no NP during the last 6 months [5 females and 5 males] and 8 subclinical NP participants who have had NP within the last 12 months [5 females and 3 males]) participated. Participants completed two mobile device tasks:​ 1) A laptop task that was one hour in duration and 2) A smartphone task that was 30 minutes in duration. Participants completed three questionnaires (mobile device usage/frequency, the Neck Disability Questionnaire and the Chronic Pain Grade Scale. Head and thorax kinematics were monitored during each condition, surface electromyography (SEMG) was monitored from six upper extremity muscles bilaterally (cervical extensors, upper trapezius and anterior deltoid) and electrocardiogram (EKG) monitored heart rate and breathing.

RESULTS & DISCUSSION:​ The laptop and smartphone tasks had similar discomfort scores reported across the same body segments used in the discomfort score questionnaire (posterior head, posterior neck, posterior left shoulder, posterior thoracic, posterior lumbar and posterior right hand and forearm). No significant differences were found for cervical extensor muscle activity. An EMG gaps analysis identified significant differences within the smartphone task for the number of gaps and average gap time for the right cervical extensor (CE), left anterior deltoid (AD) and left upper trapezius (UT). Average head/neck flexion angles were greater for the smartphone tasks than the laptop tasks. There was a difference of 7.7° of head flexion for healthy participants and 12.2° of head flexion for subclinical participant between smartphone and laptop tasks. The smartphone tasks had more gaze angles greater than -45° than the laptop tasks.

CONCLUSION:​ This work is important because it evaluated long duration smartphone and laptop computer usage, which has seen limited attention in the academic literature to date. Further investigation should attempt to determine if the differences found between groups can help identify or pre-determine if an individual may be predisposed to NP or injury due to increased device use.