Prolonged gaze at a smartphone is characterized by pronounced flexion of the cervical spine and is associated with health risks. In addition, it is suspected that smartphone distraction could lead to gait changes. Therefore, the aim of this study was to detect smartphone-associated postural changes at thoracic and lumbar levels as well as gait changes. Spinal analysis was performed prospectively in 21 healthy men using the DIERS 4Dmotion®Lab in a controlled crossover design to evaluate posture-associated parameters while standing and walking. The examination sequence provided three randomized gaze directions: GN = Gaze Neutral; S1H = Smartphone one-handed; S2H = Smartphone two-handed. Results reveal a higher vertebra prominens (VP)-flexion in S1H (23.8° ± 6.9°; p ≤ 0.001) and S2H (22.4° ± 4.7°; p ≤ 0.001) compared to GN (17.6° ± 3.8°). Kyphosis angles were also different with higher values observed in S1H (58.8° ± 5.8°; p ≤ 0.001) and S2H (61.6° ± 4.9°; p ≤ 0.001) compared to GN (49.1° ± 4.6°). During walking, similar results were observed in kyphosis angles. No differences were observed in gait during smartphone use (p = 0.180-0.883). The study revealed a significantly increased inclination of the lower cervical and thoracic spine during smartphone use. However, the inclination was larger during S2H. Standing or walking conditions did not affect the measurement outcomes. Long-term smartphone use associated with a larger inclination of the cervical and thoracic spine might result in increased pressure and shear forces acting on vertebral bodies, intervertebral discs, and muscles, which potentially increases the risk of spinal pain and disease.
Keywords: biomechanics; gait analyses; mobile; motor control; spine; surface topography; treadmill.