Slow Breathing and Resistance Exercise in Fibromyalgia (Breath-fibro)

February 4, 2026 updated by: Elena R. Serrano-Ibáñez, University of Malaga

Impact of Slow Breathing and Its Interaction With Psychological Variables From the Fear-Avoidance Model of Pain on Heart Rate Variability and Resistance Exercise Performance in Women With Fibromyalgia.

This randomized controlled trial investigates whether slow breathing techniques influence heart rate variability, exercise self-efficacy, and resistance exercise performance in women with fibromyalgia. Participants will be randomly assigned to one of three breathing conditions (slow breathing with visual pacer, slow breathing without pacer, or spontaneous breathing) before performing a biceps curl resistance exercise. The study will examine how breathing patterns interact with psychological variables (anxiety sensitivity, pain catastrophizing, pain hypervigilance, and kinesiophobia) to affect physiological and performance outcomes.

Study Overview

Status

Enrolling by invitation

Conditions

Intervention / Treatment

Detailed Description

Background: Fibromyalgia is considered one of the most representative central sensitivity syndromes, where central sensitization is the predominant characteristic. Resistance and strength training have demonstrated efficacy as therapeutic strategies for fibromyalgia patients. Slow breathing has been shown to reduce anxiety, perceived stress, and pain intensity while increasing heart rate variability (HRV), a biomarker of stress reactivity. The Fear-Avoidance Model of Pain demonstrates that anxiety sensitivity, pain catastrophizing, hypervigilance, and fear of pain/movement largely determine activity levels in chronic pain patients. However, no studies have examined how slow breathing interacts with these psychological variables to enhance resistance exercise performance in fibromyalgia patients.

Study Design: Single-session, three-arm randomized controlled trial with parallel group assignment.

Experimental Procedure:

Phase 1 - Baseline Assessment:

  • Semi-structured interview for demographic and clinical information
  • Administration of self-report questionnaires (detailed below)
  • 5-minute baseline HRV measurement (seated, eyes open, spontaneous breathing)
  • Respiration rate inferred from HRV

Phase 2 - Resistance Exercise Preparation:

  • Determination of optimal weight for biceps curl exercise using submaximal protocol
  • Warm-up: 3 minutes walking + 10 unloaded practice repetitions
  • Progressive weight testing to determine 50% 1-RM equivalent

Phase 3 - Breathing Intervention (8 minutes): Participants randomly assigned to:

  • Condition A: Slow breathing with visual pacer (6 breaths/min: 4-sec inhale, 6-sec exhale) displayed continuously
  • Condition B: Slow breathing without pacer (same pattern, brief training then self-paced)
  • Condition C: Spontaneous breathing at participant's natural rate
  • HRV continuously recorded during all breathing conditions. Respiration rate inferred from HRV.

Phase 4 - Resistance Exercise Test:

  • Biceps curl exercise at 50% estimated 1-RM
  • Maximum repetitions to voluntary exhaustion
  • Proper form maintained (back against wall, arms close to body, full range of motion)

Phase 5 - Post-Exercise Assessment:

  • Immediate measurement of dependent variables (detailed below)
  • 8 min. of rest
  • HRV recording 5 min.

Safety Monitoring: Continuous observation by trained evaluators; clear stopping criteria.

Study Type

Interventional

Enrollment (Estimated)

159

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Spain
    • Málaga
      • Málaga, Málaga, Spain, 29010
        • Asociación de Fibromialgia y Síndrome de Fatiga Crónica de Málaga (AFIBROMA)
      • Málaga, Málaga, Spain, 29010
        • Asociación de Pacientes de Fibromialgia y Síndrome de Fatiga Crónica de Málaga (APAFIMA)

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  1. Female sex
  2. Age ≥ 18 years
  3. Medical diagnosis of fibromyalgia confirmed by physician
  4. Capacity to understand and sign informed consent form
  5. Fluency in spoken and written Spanish

Exclusion Criteria:

  1. Current or past severe mental illness or neurodegenerative disease
  2. Current treatment for oncological pathology, degenerative disease, or terminal illness
  3. Musculoskeletal injury contraindicating biceps curl exercise
  4. Connective tissue disease or arthritis
  5. Inability to perform biceps curl exercise due to physical limitations

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Slow Breathing with Visual Pacer
Participants perform 8 minutes of paced slow breathing (6 breaths/min) with continuous visual guidance before resistance exercise test.
Behavioral: Slow Breathing with Visual Pacer
Participants receive brief training using a visual pacer displayed on computer screen showing a line that rises during inhalation and falls during exhalation. The pacing is set to 6 respiratory cycles per minute (4 seconds inhalation, 6 seconds exhalation). Participants place one hand below chest and abdomen to monitor diaphragmatic movement. After training, participants continue slow breathing with the visual pacer continuously displayed, maintaining the prescribed respiratory rate.
Experimental: Slow Breathing without Visual Pacer
Participants perform 8 minutes of self-paced slow breathing (6 breaths/min target) after brief training, without continuous visual guidance, before resistance exercise test.
Behavioral: Slow Breathing without Visual Pacer
Participants receive identical brief training using the visual pacer to learn the slow breathing pattern (6 cycles per minute: 4 seconds inhalation, 6 seconds exhalation). Hand placement below chest and abdomen to monitor diaphragmatic movement. After training, the visual pacer is removed and participants attempt to maintain the slow breathing pattern independently without external guidance.
Experimental: Spontaneous Breathing
Participants breathe naturally at their spontaneous rate for equivalent duration before resistance exercise test.
Behavioral: Spontaneous Breathing (Active Control)
Participants spend equivalent time breathing at their natural, spontaneous rate. They receive similar attention from evaluators but no specific breathing instructions. Participants are instructed to breathe normally at their usual pace and rhythm.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Heart Rate Variability (HRV) - Change from Baseline
Time Frame: Measured: 5 min baseline, 8 min during breathing intervention, and 5 min post-exercise recovery.
Root mean square of successive differences (RMSSD) in milliseconds
Measured: 5 min baseline, 8 min during breathing intervention, and 5 min post-exercise recovery.
Number of Biceps Curl Repetitions
Time Frame: Immediately during the resistance exercise test (single session).
Number of properly executed biceps curl repetitions at 50% estimated 1-RM performed to voluntary exhaustion with proper form maintained.
Immediately during the resistance exercise test (single session).

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Exercise-Related Self-Efficacy
Time Frame: Immediately post-exercise.
Single-item 0-10 numeric rating scale.
Immediately post-exercise.
Fatigue
Time Frame: Immediately post-exercise
Borg Rating Of Perceived Exertion. Rating of perceived exertion is an outcome measure scale used to gauge one's exercise intensity without the need to rely on physiological parameters. The scale rates exertion from a scale of 6 (no exertion) to 20 (maximum effort).
Immediately post-exercise
Change in Current Pain Intensity
Time Frame: Immediately post-exercise
Numeric Rating Scale (NRS) 0-10
Immediately post-exercise
Change in Anxiety
Time Frame: Immediately post-exercise.
Numeric Rating Scale (NRS) 0-10
Immediately post-exercise.
Perceived effort required to do the biceps exercise
Time Frame: Immediately post-exercise
Numeric Rating Scale (NRS) 0-10.
Immediately post-exercise
Breathing Difficulty
Time Frame: Immediately after breathing intervention.
Numeric Rating Scale (NRS) 0-10
Immediately after breathing intervention.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Malaga

Collaborators

Asociación de Pacientes de Fibromialgia y Síndrome de Fatiga Crónica de Málaga (APAFIMA)
Asociación de Fibromialgia y Síndrome de Fatiga Crónica de Málaga (AFIBROMA)

Investigators

  • Principal Investigator: Marcin Czub, PhD, University of Wrocław
  • Principal Investigator: Rosa Esteve, PhD, University of Malaga
  • Principal Investigator: Elena R. Serrano-Ibáñez, PhD, University of Malaga
  • Principal Investigator: Joanna Piskorz, PhD, University of Wrocław

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

February 1, 2026

Primary Completion (Estimated)

April 1, 2026

Study Completion (Estimated)

May 1, 2027

Study Registration Dates

First Submitted

February 4, 2026

First Submitted That Met QC Criteria

February 4, 2026

First Posted (Actual)

February 11, 2026

Study Record Updates

Last Update Posted (Actual)

February 11, 2026

Last Update Submitted That Met QC Criteria

February 4, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • UW-UMA_177-2025-H

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

We will share the joint database through a web link for public access.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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