Duration-dependent effects of dry cupping on autonomic modulation and trapezius tissue compliance in smartphone users: a dose-finding study

Background Prolonged smartphone use is associated with forward head posture, increased trapezius stiffness, and altered autonomic nervous system regulation. Dry cupping applies localized negative pressure-mediated mechanical stimulation that may influence myofascial properties and autonomic activity; however, its interactive effects of pressure and duration remain unclear. This study investigated the effects of different pressure and duration combinations of dry cupping on autonomic modulation indexed by heart rate variability (HRV) and trapezius tissue compliance in smartphone users. Methods Thirty-two university students were classified into the smartphone addiction and control groups. A counterbalanced crossover design was implemented, in which each participant received four cupping protocols: ˗300 mmHg or ˗450 mmHg applied for 5 or 15 min. HRV, trapezius soft tissue compliance measured using a real-time monitoring system, and functional questionnaires were assessed before and after each intervention. Results HRV spectral indices indicated reduced sympathetic activity and did not reach statistical significance for parasympathetic activity (p=0.062) following cupping. Compared to 5-min sessions, 15-min protocols significantly increased total power as well as both low- and high-frequency components. Trapezius tissue compliance showed the highest improvement after ˗300 mmHg applied for 15 min. Functional disability scores remained unchanged. Conclusion In this subclinical population, dry cupping modulated autonomic activity and improved trapezius tissue compliance in a duration-dependent manner, with 15-minute applications generally producing greater effects than 5-minute applications. Treatment duration exerted a greater influence than pressure intensity, with moderate pressure sustained for 15 min producing the most pronounced autonomic and biomechanical responses.