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.
Study Type
OBSERVATIONAL
Enrollment
84
All participants will undergo a standardized assessment protocol including measurement of smartphone addiction level, daily smartphone screen time from the past 7 days, dominant hand grip strength, thumb pinch strength, wrist proprioception, and thumb proprioception in a single session
Saglik Bilimleri Universitesi
Istanbul, Uskudar, Turkey (Türkiye)
Hand Grip Strength
Hand grip strength will be measured using a hydraulic hand dynamometer. The participant will be in a seated position with the elbow flexed at 90 degrees. Three measurements will be taken with a 10-second rest between each, and the average value will be recorded in kilograms (kg).
Time frame: Single assessment at baseline
Thumb Pinch Strength
Thumb muscle strength will be measured using a pinchmeter. The participant will be seated with the elbow flexed at 90 degrees and the wrist in a neutral position. The average of three trials will be recorded in kilograms (kg).
Time frame: Single assessment at baseline
Thumb Active Joint Position Sense (JPS)
Measured using a standard transparent plastic goniometer. The researcher will passively move the thumb to a 30-degree abduction target position. The participant will be asked to actively reproduce this angle. The absolute error between the target angle and the reproduced angle will be recorded in degrees.
Time frame: Single assessment at baseline
Wrist Joint Position Sense (JPS)
Measured using a goniometer with the participant's eyes closed. The wrist will be passively moved to predetermined positions (30 degrees flexion, 30 degrees extension, 10 degrees radial deviation, and 15 degrees ulnar deviation). The participant will then actively reposition the wrist, and the absolute error will be calculated in degrees.
Time frame: Single assessment at baseline
Smartphone Screen Time
Objective measurements of the participants' smartphone use over the last 7 days will be obtained. Data will be collected using built-in features such as "Screen Time" for iOS devices or "Digital Wellbeing" for Android devices.
Time frame: Single assessment at baseline
Smartphone Addiction Scale-Short Form
The Smartphone Addiction Scale-Short Form (SAS-SF) was used to assess smartphone addiction. The scale comprises 10 items rated on a 6-point Likert scale (1 = strongly disagree to 6 = strongly agree), yielding a total score between 10 and 60. Higher scores reflect a higher risk or severity of smartphone addiction.
Time frame: Single assessment at baseline
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