EFFECT OF SMARTPHONE ADDICTION ON PEAK TORQUE AND ENDURANCE OF SHOULDER ROTATORS : A Cross-Sectional Study

Background: Smartphones have become essential tools for communication, internet browsing, and entertainment. Over the past decade, the rate, duration, and frequency of smartphone usage have increased significantly. However, excessive smartphone use often leads to poor posture, such as forward head posture and rounded shoulders, which places undue stress on the shoulder complex and rotator cuff muscles that are critical for maintaining shoulder stability. Purpose: A correlational cross sectional study was conducted to evaluate the effect of smartphone addiction on peak torque and endurance of shoulder rotators measured from the scapular plane. Methods: A total of 79 individuals, ranging in age from 18 to 30, were included in the study. The Arabic short version of the smartphone addiction scale was applied for assessing subjects for smartphone addiction and the Biodex system 3 isokinetic dynamometer was utilized for measuring peak torque and endurance of the shoulder rotators. Results: Pearson correlation analysis demonstrated a strong statistically significant negative correlation between the SAS score and all tested outcomes: peak torque of internal rotators (r = -0.711, p < 0.0001), peak torque of external rotators (r = -0.669, p < 0.0001), and endurance of both internal (r = -0.732, p < 0.0001) and external rotators (r = -0.768, p < 0.0001). Conclusion: Elevated smartphone addiction levels correlate with significant reductions in both peak torque and endurance of the shoulder rotators, suggesting that excessive smartphone use may contribute to weakened shoulder musculature and reduced functional capacity, potentially increasing the risk of musculoskeletal dysfunction over time.