Smartphone Use and Hand Function in Young Adults

The Relationship Between Daily Smartphone Use Duration and Dominant Hand Grip Strength, Thumb Strength, Wrist and Thumb Proprioception in Young Adults

This observational cross-sectional study aims to investigate the relationship between daily smartphone usage duration and hand function parameters in young adults. Specifically, the study will examine the association between smartphone screen time and dominant hand grip strength, thumb strength, and wrist and thumb proprioception. Healthy individuals aged 18-35 years will be included. All participants will undergo a single-session assessment including measurement of smartphone usage duration, hand grip strength, pinch strength, and joint position sense of the wrist and thumb. The findings are expected to provide insight into the potential effects of prolonged smartphone use on hand function and proprioceptive performance in young adults.

The widespread use of smartphones in daily life has increased significantly, particularly among young adults. While these devices provide convenience and accessibility, excessive smartphone use has been associated with various musculoskeletal and functional impairments, particularly in the upper extremity. Repetitive thumb movements, sustained grip positions, and prolonged device use may negatively affect muscle strength, joint proprioception, and overall hand function. Previous studies have reported that excessive smartphone use may lead to decreased grip strength, altered thumb mechanics, and impaired proprioception. However, there is limited research directly examining the relationship between objectively measured smartphone usage duration and detailed hand function parameters. This study is designed as a cross-sectional, observational, and analytical investigation. Healthy individuals aged 18-35 years will be recruited. Participants with a history of upper extremity injury, neurological disease, or musculoskeletal disorders affecting the hand and wrist will be excluded. All participants will be evaluated in a single session. Demographic data and clinical history will be recorded. Smartphone usage duration will be obtained from built-in device tracking systems (Screen Time for iOS and Digital Wellbeing for Android) based on the last 7 days of use.

Inclusion Criteria:

• Healthy adults
• Aged between 18 and 35 years
• Voluntary participation in the study

Exclusion Criteria:

• History of hand or wrist surgery
• Fracture or serious injury in the hand/thumb within the last 6 months
• Neurological disorders
• Rheumatologic diseases
• Cognitive impairment preventing understanding of instructions