"Physiological Responses to Manual Pressure in Healthy Adults"

This randomized experimental study will investigate how different intensities and application patterns of manual pressure applied to the upper trapezius muscle affect physiological responses in healthy adults. Participants will be randomly assigned to one of three groups: (A) graded sustained pressure at a single point over the upper trapezius, (B) graded longitudinal kneading over a defined area of the upper trapezius, or (C) three standardized manual therapy protocols with increasing pressure (manual lymphatic drainage, light-pressure massage and moderate-pressure massage).

In groups A and B, five individualized pressure levels (0, 25, 50, 75 and 95% of each participant's pressure pain threshold) will be delivered for 2 minutes each in a single session. In group C, each participant will receive the three manual therapy protocols in separate randomized sessions. Autonomic (heart rate and heart rate variability), hormonal (capillary cortisol and VEGF in group C), sensory (mechanical pain thresholds), hemodynamic (blood pressure) and, in group C, vascular (left common carotid artery ultrasound) responses will be recorded before and after the interventions. The study will provide dose-response and mechanistic information to inform safer and more individualized manual therapy protocols.