NCT07393815

"Physiological Responses to Manual Pressure in Healthy Adults"

Physiological Responses to Graded Manual Pressure in Healthy Adults: a Randomized Experimental Study on Autonomic, Hormonal, Sensory and Vascular Outcomes

• Status: Not Yet Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 90 (estimated)
• Sponsor: Universidad Europea de Madrid · Academic / Other
• Sex: All
• Age: 18 Years – 65 Years
• Healthy volunteers: Accepted

Summary

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.

Detailed description

This prospective randomized experimental study will be conducted in healthy adults to characterize acute physiological responses to different intensities and patterns of manual pressure applied to the upper trapezius muscle. Participants will be randomly allocated to one of three experimental groups: * Group A - Graded sustained pressure: a personalized pressure scale is defined based on the individual pressure pain threshold (PPT) measured with an algometer. Five pressure levels are set at 0% (contact without pressure), 25%, 50%, 75% and 95% of PPT, and applied as sustained pressure at a single point over the upper trapezius. * Group B - Graded longitudinal kneading: the same personalized pressure scale (0, 25, 50, 75 and 95% of PPT) is applied as longitudinal kneading distributed over a predefined area of the upper trapezius. * Group C - Manual therapy protocols: each participant receives three standardized manual therapy protocols in separate sessions, with randomized order: manual lymphatic drainage (approx. 40 minutes at \~40 mmHg), light-pressure massage (0.5-0.8 N/cm², 20-30 minutes) and moderate-pressure massage (2-3 N/cm², 20 minutes), all targeting the upper trapezius and related regions. In groups A and B, the five pressure levels are each applied for 2 minutes in a single experimental session, in randomized order, with rest periods of at least 5 minutes between levels (extended if needed until heart rate returns within ±10% of baseline). In group C, each manual therapy protocol is applied in a separate session with at least one day between sessions. In all groups, heart rate and heart rate variability are recorded continuously with a chest strap, and skin temperature and skin conductance are continuously monitored with surface sensors. Blood pressure, mechanical pain thresholds (von Frey filaments at predefined trapezius and forearm sites), and capillary blood samples for cortisol are obtained at baseline and immediately after each pressure level or massage protocol. In group C, VEGF is also measured in capillary blood. In group C only, duplex ultrasound of the left common carotid artery is performed under standardized conditions (semi-recumbent position, head rotated 45° to the right) before the manual therapy protocol and 10 minutes after its completion, to assess luminal diameter, intima-media thickness and peak systolic velocity. All pressure applications in all groups are monitored with a pressure-sensing system (Loadpad) placed on the therapist's hand. A separate visit includes whole-body dual-energy X-ray absorptiometry (DEXA) to characterize body composition (total and segmental lean mass and fat mass). The main outcome is a heart rate variability index (e.g., RMSSD), while hormonal (cortisol, VEGF in group C), sensory (pain thresholds), hemodynamic (blood pressure) and vascular (carotid ultrasound in group C) measures are considered secondary outcomes. The study is powered assuming a large effect size on HRV based on previous massage research, with a planned sample size of 30 participants per group (N = 90).

Conditions

• Healthy Participants

Interventions

Type	Name	Description
OTHER	"Manual Pressure Protocol"	Manual pressure is applied over the upper trapezius muscle using five individualized pressure levels (0, 25, 50, 75 and 90% of the pressure pain threshold). Each level is applied for 2 minutes in a single experimental session, with randomized order and rest periods between applications. In the Sustained Pressure arm, pressure is maintained at a single point. In the Longitudinal Kneading arm, the same pressure levels are distributed along a predefined area using a kneading technique.
OTHER	Manual Therapy Protocols (DLM, light and moderate-pressure massage)	Three standardized manual therapy protocols targeting the upper trapezius and related regions are applied in separate sessions with at least one day between them and randomized order: (1) manual lymphatic drainage (approx. 40 minutes at \~40 mmHg), (2) light-pressure massage (0.5-0.8 N/cm², 20-30 minutes) and (3) moderate-pressure massage (2-3 N/cm², 20 minutes). Pressure is monitored continuously with a hand-worn pressure sensor.
OTHER	Graded Sustained Pressure	Manual pressure applied over the upper trapezius using five individualized pressure levels (0, 25, 50, 75 and 95% of the pressure pain threshold) delivered as sustained pressure at a single point, 2 minutes per level in a single session, with randomized order and rest periods between applications.

Timeline

• Start date: 2026-03-01
• Primary completion: 2026-05-01
• Completion: 2026-07-01
• First posted: 2026-02-06
• Last updated: 2026-02-06

Locations

1 site across 1 country: Spain