This observational cross-sectional study examined associations among second-to-fourth digit ratio, handgrip strength, problematic smartphone-use symptoms, problematic Internet-use symptoms, and self-reported smartphone usage time in university students from different regional backgrounds. The analytic sample included 173 students aged 17-26 years from Turkish, Middle Asian, African, and Asian regional backgrounds. Participants completed validated self-report scales for smartphone-use and Internet-use symptoms, and underwent anthropometric, hand morphology, and handgrip strength measurements. The study did not involve randomization, treatment assignment, intervention, or follow-up.
This exploratory observational cross-sectional study evaluated whether bilateral second-to-fourth digit ratio and handgrip strength were associated with smartphone-addiction symptom scores, Internet-addiction symptom scores, and self-reported smartphone usage time among university students from different regional backgrounds. The final analytic sample consisted of 173 participants aged 17-26 years, including Turkish, Middle Asian, African, and Asian students. Regional-background comparisons and sex-specific associations were analyzed using descriptive statistics, group comparisons, correlation analyses, and sensitivity analyses adjusted for age and body mass index. The study was observational only and did not include any intervention, random allocation, treatment exposure, clinical procedure, or prospective follow-up.
Study Type
OBSERVATIONAL
Enrollment
173
Bandırma Onyedi Eylül University
Balıkesir, Turkey (Türkiye)
Internet-addiction symptom score
Internet-addiction symptoms assessed using the Young Internet Addiction Scale-Short Form. Higher scores indicate greater Internet-use symptom severity.
Time frame: At baseline / single cross-sectional assessment
Smartphone-addiction symptom score
Smartphone-addiction symptoms assessed using the Smartphone Addiction Scale-Short Version. Higher scores indicate greater smartphone-use symptom severity.
Time frame: At baseline / single cross-sectional assessment
Second-to-fourth digit ratio
Right and left second-to-fourth digit ratios calculated from index and ring finger lengths measured using a digital caliper.
Time frame: At baseline / single cross-sectional assessment
Handgrip strength
Right and left handgrip strength measured using an electronic handgrip dynamometer.
Time frame: At baseline / single cross-sectional assessment
Self-reported smartphone usage time
Daily smartphone usage time reported by participants in hours per day.
Time frame: At baseline / single cross-sectional assessment
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