Comparison of Wrist Deviation Strength and Range of Motion in Food Service Workers With and Without Ulnar-Sided Wrist Pain

Chronic pain Food services Muscle strength Occupational diseases Range of motion, articular Wrist jointBackground: Modern service-oriented occupations have increased concern regarding workrelated musculoskeletal disorders (WMSDs).Food service workers (FSWs) are at elevated risk of wrist-related WMSDs because their duties involve repetitive wrist movements during cooking, utensil handling, and tray carrying.Although ulnar deviation is frequently used in these tasks, ulnar-sided wrist pain (USWP) may be accompanied by direction-specific limitations and functional imbalance.Objects: This study aimed to compare radial and ulnar deviation strength and range of motion (ROM) between FSWs with and without USWP.Methods: Thirty FSWs were classified into USWP (n = 15) and non-USWP (n = 15) groups.USWP was defined as dominant-side pain lasting more than 3 months, a numeric pain rating scale score of ≥ 4 during work, and tenderness reproduced by the ulnar fovea sign test.Active wrist radial deviation ROM (WRDR) and ulnar deviation ROM (WUDR) were measured using a goniometer.Maximal voluntary isometric radial and ulnar deviation strengths were measured using a Smart KEMA strength sensor and normalized to body weight.ROM and strength asymmetry index (AI) were calculated to quantify directional imbalance. Results:The USWP group showed significantly lower WRDR (p = 0.002) and a higher ROM AI (p = 0.001) than the non-USWP group.Normalized radial deviation strength (p < 0.001) and ulnar deviation strength (p = 0.036) were also significantly lower in the USWP group, whereas the strength AI was significantly higher (p < 0.001).No significant between-group differences were observed in WUDR or raw ulnar deviation strength.Conclusion: USWP in FSWs was associated with reduced radial deviation ROM, lower normalized wrist deviation strength, and greater directional asymmetry.These findings suggest that USWP should not be viewed as localized ulnar-sided pain, but as a condition involving altered wrist deviation function.Pain-related limitation or neuromuscular factors may have contributed; however, causality requires caution.