Date of Graduation


Document Type


Degree Name

Master of Science in Kinesiology (MS)

Degree Level



Health, Human Performance and Recreation


Kaitlin Gallagher

Committee Member

Erin K. Howie

Second Committee Member

Lesley Vandermark


Reliability, Smartphone Use


The accessibility of mobile technology has improved productivity but can contribute to musculoskeletal disorders due to the posture associated with using such devices. Neck flexion, a posture assumed by smartphone users, has been shown as a risk factor for the development of clinical neck pain if sustained for prolonged periods. Determining the individuals who are naturally more predisposed to develop flexion-induced neck pain can aid in the prevention and treatment of musculoskeletal disorders. The purpose of this thesis is to assess the repeatability of clinical tests between trials over the course of two days in young adults who do and do not develop neck pain after 30 minutes of smartphone use. Healthy participants (n=41) ages 18- 29 (21.6 ±2.12) underwent a battery of clinical tests used in populations with chronic neck pain. Tests included pain pressure threshold (PPT) testing, cervical and craniocervical flexion, and a cervical extensor (CE) fatigue assessment. Afterwards, each participant spent 30 minutes using their personal smartphone for a series of predetermined tasks. During the 30 minutes, participants completed 5 visual analog scales (VAS) that helped categorize them into 2 separate pain groups: pain developers (PD) or non-pain developers (NDP). Clinical tests were repeated after the smartphone use intervention and participants returned for a second data collection 1 to 2 weeks later. Intraclass correlation coefficients (ICC) were calculated for pre- and post- smartphone use variables between days 1 and 2 to determine repeatability of the clinical tests in this population. A McNemar chi-square test was used to determine the number of participants who remained in their initial pain groups on day 2 of data collection. NPD had greater between day reliability for PPT measurements taken before the intervention, while PD had higher ICC values after 30 minutes of smartphone use. The cervical extensor fatigue assessment and cervical flexion protocols had higher reliability before and after the smartphone use intervention in the PD group. An assessment of the pain response to pressure stimulus, cervical flexion, and CE fatigue are recommended as protocols to differentiate individuals who do and do not develop pain after 30 minutes of smartphone use.