The Effects of Smartphone Addiction on Pinch Strength, Muscle Stiffness, and Hand/Wrist Function in Young Adults

July 26, 2026 updated by: Aysem Ecem Ozdemir, Istanbul Gelisim University

The Effects of Smartphone Addiction on Pinch Strength, Muscle Stiffness, and Hand and Wrist Function in Young Adults: A Cross-Sectional Study

Smartphones have become an indispensable part of daily life, and their increasing use has raised concerns about various health effects, including musculoskeletal symptoms. Repetitive movements of the thumb and hand muscles can lead to issues such as tendinosis, myofascial pain syndrome, and a decrease in pinch strength. Studies have shown that musculoskeletal symptoms related to smartphone use are common among young adults and university students. Additionally, an increase in device size may place greater strain on the wrist and finger muscles. Repetitive movements can cause stiffness changes in the thumb muscles, and the relationship between these changes and pinch strength is considered an important research topic. In this study, we aimed to investigate the effects of smartphone addiction on pinch strength, muscle stiffness, hand/wrist pain, and function in young adults.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

This study was designed as a cross-sectional study. Volunteers eligible to participate were first screened based on the results of the Smartphone Addiction Scale-Short Version (SAS-SV), and they were divided into two groups as Smartphone Addiction and Non-Smartphone Addiction, with a cutoff score of 31 for males and 33 for females. Subsequently, the determination of dominant hand was performed. All assessments were conducted on the participants' dominant extremity. The assessments were carried out in the following order: Patient-Rated Wrist/Hand Evaluation Questionnaire (PRWHE), the Finkelstein test, muscle stiffness measurement, and finally, pinch strength assessment, as it was considered to potentially cause fatigue. All assessments were conducted by expert physiotherapists within a total duration of 30 minutes, and participants were not followed up afterward, nor recieved any intervention.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
134

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • Turkey (Türkiye)
    • Kağıthane
      • Istanbul, Kağıthane, Turkey (Türkiye), 34320
        • Istanbul Kent University

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Sampling Method

Non-Probability Sample

Study Population

University student from Istanbul Kent University and Istanbul Gelisim University.

Description

Inclusion Criteria:

  • Willing to participate in the study
  • Have been using a smartphone for more than one year
  • Aged between 18 and 25 years
  • Send 25 or more text messages or emails per day
  • Spend more than 2 hours browsing the internet and/or play games for more than one hour a day

Exclusion Criteria:

  • Having radiating/radicular pain in the upper extremity
  • Having neck pain
  • Congenital deformities in the upper extremity and neck
  • A history of diagnosed neurological, rheumatic, musculoskeletal, or cardiovascular diseases
  • Having previously undergone surgery on the neck and/or upper extremity
  • Having been diagnosed with De Quervain's disease or tendinopathy in the hand/hand wrist muscles before

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Smartphone Addiction Group
Individuals classified as having smartphone addiction based on the Smartphone Addiction Scale-Short Version (SAS-SV). Participants in this group scored 31 or higher for males and 33 or higher for females on the SAS-SV, indicating problematic smartphone use that meets the threshold for addiction.
Other: No intervention.
Participants allocated to the groups were assessed only once. No intervention was applied, and they were not followed up.
Non-Smartphone Addiction Group
Individuals who are not classified as having smartphone addiction based on the Smartphone Addiction Scale-Short Version (SAS-SV). Participants in this group scored below 31 for males and below 33 for females on the SAS-SV, indicating that their smartphone use does not meet the threshold for addiction.
Other: No intervention.
Participants allocated to the groups were assessed only once. No intervention was applied, and they were not followed up.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Muscle Stiffness
Time Frame: Baseline
Muscle stiffness (Abductor Pollicis Brevis, Abductor Pollicis Longus and Extensor Pollicis Brevis) was measured using the MyotonPRO (Myoton SA, Tallinn, Estonia) device. A brief mechanical impulse was applied to the muscle and then quickly released. Stiffness (N/m) is a parameter related to the capacity to withstand an external force. The reliability of the device has been proven in healthy individuals. The measurement site was marked on the skin with a pen. In all applications, the MyotonPRO probe was placed perpendicular to the skin, and in multi-scan mode, three measurements were recorded with 10 pulses at 1-second intervals. The average of the three measurements was used for analysis.
Baseline
Pinch Strength
Time Frame: Baseline
Lateral and palmar pinch strength were measured in kilograms using a Jamar hydraulic pinch gauge (ICC: 0.94-0.99). The measurements were performed in the standard position recommended by the American Society of Hand Therapists: seated, with the shoulder in adduction and neutral, elbow in 90 degrees of flexion, forearm in mid-rotation and supported, and wrist in neutral. Three consecutive measurements, each lasting five seconds, were taken, with one-minute rest intervals between each measurement to prevent muscle fatigue. The average of the three trials was used for analysis.
Baseline

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Smartphone Addiction Scale-Short Version (SAS-SV)
Time Frame: Baseline
The SAS-SV is a 10-item scale developed by Kwon and colleagues to measure the risk of smartphone addiction in adolescents. It is evaluated using a six-point Likert scale. The scale items are scored from 1 to 6. The scale scores range from 10 to 60, with higher scores indicating an increased risk of addiction. The scale is unidimensional and does not have subscales. In the Korean sample, the cutoff score is 31 for males and 33 for females.
Baseline
Patient-Rated Wrist/Hand Evaluation Questionnaire (PRWHE)
Time Frame: Baseline
This form consists of two subscales: a pain subscale with five items, a specific function subscale with six items, and a daily function subscale with four items. Each item is scored on a scale from 0 to 10. In this scale, pain and function problems are weighted equally, and the total score is measured out of 100 points.
Baseline
Finkelstein Test
Time Frame: Baseline
The Finkelstein test, one of the most commonly preferred clinical examination tests for diagnosing De Quervain's disease, was used. Participants were asked to make a fist with their thumb inside, and the researcher passively deviated the fist ulnarly. The presence of tenderness and pain at the radial styloid indicated a positive test.
Baseline
Smartphone Surface Area
Time Frame: Baseline
The dimensions of the smartphones used by the participants were measured by the researchers. Using a measuring tape, the width and length of the smartphone were recorded in centimeters. The value used for statistical analysis was determined as the surface area of the smartphone (width × length).
Baseline

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Istanbul Gelisim University

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Istanbul Kent University
Istanbul University - Cerrahpasa

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 15, 2024

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 5, 2026

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 5, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 18, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 22, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 25, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
July 28, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
July 26, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
July 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • IUC002

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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