Evaluating hand performance and strength in children with high rates of smartphone usage: an observational study.

[Purpose] This study investigated the interaction effects between the levels of smartphone use and hand dominance on handgrip, pinch strengths, and functional hand performance in children. [Participants and Methods] A total of 60 children aged between 9 and 15 were assigned into two groups: Group A (high-frequency smartphone users) and Group B (low-frequency smartphone users). Use levels were determined according to the smartphone addiction scale-short version. A hand dynamometer and pinch gauge were used to measure handgrip and pinch strength respectively. Functions of the upper extremity and hand were scored using the Quick Disabilities of the Arm, Shoulder, and Hand questionnaire. [Results] Group A participants had reduced measurements in hand grip and pinch strength, especially in the dominant hand. However, Quick Disabilities of the Arm, Shoulder, and Hand scores indicated that hand function was decreased in the dominant hand whether the child was a high- or low-frequency smartphone user. [Conclusion] Results indicated that high levels of smartphone use diminished hand and pinch-grip strengths as well as and hand function. That is, hand and pinch-grip strengths were reduced in the dominant hands of high-frequency smartphone users. However, hand functions were affected in the dominant hands among both high and low-level smartphone users.