Heart Rate Variability Biofeedback in Security Forces
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18-55
SponsorEgas Moniz - Cooperativa de Ensino Superior, CRL
About this trial
This exploratory study evaluates the effectiveness of a 12-session Heart Rate Variability Biofeedback (HRV-BFB) protocol in reducing distress and burnout while promoting psychological well-being among Portuguese National Republican Guard (GNR) professionals. Exposed to high occupational stress from unpredictable risks, shift work, and limited resources, these individuals face elevated vulnerability to chronic stress outcomes. The intervention leverages real-time HRV feedback to enhance autonomic regulation, breathing techniques, and emotional self-regulation.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
Operational military personnel of the Guarda Nacional Republicana (GNR) performing security, patrol, criminal investigation, or road safety duties
Any military rank or professional category within operational roles
Age between 18 and 55 years, inclusive
Both males and females
Disqualifiers
Extended sick leave or medical absence
Currently involved in serious disciplinary proceedings
Use, modification, or initiation of psychotropic medication (including antidepressants, anti-anxiety medications, antipsychotics, mood stabilizers) within the past 6 months
Trial design
Design model
Parallel
Treatments tested in this trial
Heart Rate Variability Biofeedback (HRV-BFB) Training
BehavioralParticipants receive a structured heart rate variability biofeedback (HRV-BFB) training protocol delivered over 4 weeks. The intervention uses a portable chest-worn ECG sensor (eSense Pulse) connected via Bluetooth to a mobile application that provides real-time visual feedback of heart rate variability. Each participant completes 12 individual sessions of 12 minutes each (one session every 2 days). Sessions take place in a quiet room and follow a standardized format: a brief preparation phase, followed by approximately 10 minutes of guided breathing at resonance frequency (around 6 breaths per minute) using a visual breathing guide. The application displays color-coded feedback indicating how closely the participant's physiological response matches the target HRV pattern, and participants are instructed to adjust their breathing and recall positive memories to maximize time in the desired state. The aim is to increase HRV, strengthen parasympathetic activation, and improve stress and
Treatment groups
50 Participants
are divided into 2 treatment groupsGroup A: HRV Biofeedback TrainingExperimental treatment 1 intervention
Group B: Control: No InterventionNo intervention 0 interventions
Trial outcomes
Primary outcomes
1
Change in Psychological Distress (Kessler Psychological Distress Scale - K10)
The Kessler Psychological Distress Scale (K-10) is a 10-item self-report measure assessing psychological distress over the past 30 days. Items measure anxiety and depressive symptoms on a 5-point Likert scale (1=never to 5=always). Total score range: 10-50 (higher scores indicate greater distress). Portuguese validation: α=0.91. Primary outcome is change from baseline to post-intervention (week 4) and follow-up (week 10).
Time frame
Baseline (Week 0), Post-intervention (Week 4), Follow-up (Week 10)2
Change in Occupational Burnout (Burnout Assessment Tool - BAT-12)
The Burnout Assessment Tool Short Form (BAT-12) is a 12-item self-report measure of occupational burnout across 4 dimensions: exhaustion (3 items), mental distance (3 items), cognitive impairment (3 items), emotional impairment (3 items). 5-point Likert scale (1=never to 5=always). Total score range: 12-60. Portuguese validation: α=0.85. Primary outcome is change from baseline to post-intervention and follow-up.
Time frame
Baseline (Week 0), Post-intervention (Week 4), Follow-up (Week 10)3
Change in Psychological Well-Being (WHO-5 Well-Being Index)
The WHO-5 Well-Being Index is a 5-item self-report measure of psychological well-being over the past 2 weeks. Items assess positive mood, vitality, sleep, daily functioning, and life satisfaction on a 0-5 scale. Total score range: 0-25 (higher=higher well-being). Primary outcome is change from baseline to post-intervention and follow-up.
Time frame
Baseline (Week 0), Post-intervention (Week 4), Follow-up (Week 10)Secondary outcomes
1
SDNN (Standard Deviation of NN Intervals) - Heart Rate Variability
SDNN measures the standard deviation of the average NN (R-R) intervals in milliseconds during a recording period. It is a general indicator of overall heart rate variability and reflects the body's overall capacity for physiological adaptation and autonomic flexibility. Higher SDNN values indicate better autonomic regulation.
Time frame
Baseline (Week 0), after each of 12 training sessions2
RMSSD (Root Mean Square of Successive Differences) - Parasympathetic Activity
RMSSD measures the root mean square of successive differences between adjacent NN (R-R) intervals in milliseconds. It is a primary time-domain measure of high-frequency heart rate variability and specifically reflects parasympathetic (vagal) nervous system activity and the body's recovery capacity. Higher RMSSD indicates stronger parasympathetic tone.
Time frame
Baseline (Week 0), after each of 12 training sessions3
Stress Index - Autonomic Balance Indicator
The Stress Index is a proprietary metric derived from heart rate variability analysis that quantifies autonomic nervous system balance. Lower values indicate better autonomic regulation and lower physiological stress levels. Higher values reflect sympathetic dominance and poorer stress adaptation.
Time frame
Baseline (Week 0), after each of 12 training sessionsSponsors and contacts
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Source ClinicalTrials.gov