Comparative analysis of spinal flexion angles during smartphone use in toilet: a randomized cross-over with three-period study.

: The purpose of this study was to quantify the impact of smartphone use while sitting on the toilet on the spinal flexion angles and the time effect. : Measurements of the spinal flexion angles in the sagittal plane were made by thirty participants while they sat on the toilet for 10 min, using a smartphone in either one, both, or neither hand. The individual's forehead, cervical, thoracic and lumbar spinal areas were each fitted with five different inertial motion sensors. SPSS 26.0 software was used to statistically evaluate all of the data. : People who used smartphones with both hands had considerably larger ( < 0.05) cervical and spinal flexion angles than those who did not. A statistically significant ( < 0.001) association was observed by regression analysis between time and spinal flexion angle ( = 0.747 for no smartphone, = 0.793 for a smartphone used in one hand and = 0.855 for a smartphone used in both hands). Consequently, when using the smartphone with both hands, the flexion angle of the spine entered a more stable state of angles. : The results showed that the cervical region's flexion angles change when using a smartphone while sitting on the toilet. Even when not using a smartphone, the flexion angle of the spine when sitting on the toilet will progressively increase.