Relationships between cervical sagittal posture, muscle endurance, joint position sense, range of motion and level of smartphone addiction

Abstract Background: Frequent smartphone use in a pathological way forces the user to adopt a compromised posture. This gradually results in changes to both the postural and musculoskeletal systems. This study’s objectives were evaluation of head posture, muscle endurance, neck range of motion (ROM) and joint position sense in two separate smartphone user groups, one ‘Addicted’, the other ‘Non-Addicted’. Methods: A sample of convenience (n=60) were recruited from medical students (age 24.57±4.38, 53.3 % male) with a history of smartphones use >2 hours/day for 1-year. Based on the cut-off values of the smartphone addiction scale-short version (SAS-SV, male=31, female=33), participants were entered into each group. Neck muscle endurance time, joint position error and cervical ROM, along with forward head posture parameters of craniovertebral angle (CVA), shoulder angle (SA), sagittal head angle (SHA) and forward head distance (FHD)) were evaluated. A Mann-Whitney test and Spearman correlation coefficient were used to determine the difference between groups and the correlations between variables.Results: The difference between 'Addicted’ and ‘Non-Addicted’ groups was confirmed by the values for SAS-SV scores (25.23±5.5 versus 43.9±6.61) (p<0.001). There were statistically significant differences between groups for neck extensor muscle endurance (97±3.79 versus 74.86±2.23), (p=0.01) and between CVA and FHD parameters (p0.05).Conclusions: The positive correlation between smartphone addiction and both decreased extensor muscle endurance and changes in neck postural alignment is concerning.