How Different Breathing Methods Affect Brain Activity in Young Adults With Chronic Ankle Instability (BRAIN-CAI)

November 11, 2026 updated by: hyeongju Yoon, Gwangju Health University

Comparative Analysis of Breathing Intervention Types on Neural Activation in Young Adults With Chronic Ankle Instability: An fNIRS-EEG Randomized Controlled Trial

Chronic ankle instability is a common condition that can affect balance, movement control, and daily activities in young adults. Breathing exercises may influence brain function and attention, but their immediate effects on brain activity in individuals with chronic ankle instability are not well understood.

This randomized controlled trial aims to investigate the immediate effects of different breathing interventions on brain activity in young adults with chronic ankle instability. Participants will be randomly assigned to different breathing intervention groups. Brain activity will be assessed before and after the intervention using functional near-infrared spectroscopy (fNIRS) and electroencephalography (EEG). The findings may improve understanding of the relationship between breathing exercises and brain function and support the development of rehabilitation strategies for individuals with chronic ankle instability.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Background and Rationale Chronic ankle instability (CAI) is a common sequela of lateral ankle sprain, characterized by recurrent giving way, perceived instability, and impaired dynamic balance. Growing evidence suggests that CAI involves not only peripheral deficits but also altered central nervous system processing, including changes in prefrontal cortical activity. Breathing-based interventions may influence postural control as well as cortical and autonomic regulation. However, it remains unclear how different types of breathing interventions compare in their immediate effects on brain activity in individuals with CAI. This study compared three breathing interventions: diaphragmatic breathing training, VR-based breathing meditation, and neurofeedback-based brain relaxation training.

Study Design This was a parallel-group, assessor-blinded randomized controlled trial. Thirty-three young adults with CAI were randomly allocated to one of three groups (n = 11 per group): the Diaphragmatic Breathing Group (DBG), the VR-based Breathing Meditation Group (VMG), or the Neurofeedback Brain Relaxation Training Group (NRG). Outcome assessors were blinded to group allocation. Each participant received a single intervention session according to group assignment, and outcomes were assessed before and immediately after the intervention. The study was designed and reported in accordance with the CONSORT guidelines.

Interventions The DBG performed diaphragmatic breathing training. The VMG performed breathing meditation delivered through a virtual reality environment. The NRG performed brain relaxation training based on EEG neurofeedback. The three groups differed in the type of breathing intervention while all received a single session. Detailed intervention procedures are described in the Arms and Interventions section.

Outcome Assessment The primary outcomes were cortical activity and EEG-based self-regulation indices. Cortical activity was measured by functional near-infrared spectroscopy (fNIRS) as oxygenated hemoglobin (HbO2) concentration in prefrontal regions of interest, including the dorsolateral prefrontal cortex, frontopolar cortex, orbitofrontal cortex, and medial prefrontal cortex. Neural self-regulation was evaluated using indices derived from EEG neurofeedback. The secondary outcomes were diaphragm contractility, measured as diaphragm thickening fraction using ultrasound; dynamic balance, measured by the Star Excursion Balance Test (SEBT); and ankle instability. Detailed outcome definitions and time frames are described in the Outcome Measures section.

Statistical Analysis Between-group differences were analyzed using analysis of variance (ANOVA), and within-group changes from pre- to post-intervention were analyzed using paired t-tests. Associations among fNIRS, EEG, and balance variables were examined using Pearson correlation analysis. Effect sizes were reported as Cohen's d. Bonferroni correction was applied where multiple comparisons were made. The significance level was set at 0.05.

Significance The findings of this study are expected to clarify how different types of breathing interventions immediately modulate prefrontal cortical activity and neural self-regulation in individuals with CAI, and to provide a basis for neuroscience-informed rehabilitation strategies for CAI.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
33

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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

  • South Korea
      • Gwangju, South Korea, 62287
        • Recruiting
        • Gwangju Health University
        • Contact:
        • Contact:

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 34 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Young adults
  • CAIT-K score of ≤24
  • A history of at least one ankle sprain occurring at least 12 months prior to study enrollment
  • At least two episodes of ankle "giving way" within the 6months precending study enrollment

Exclusion Criteria:

  • A sprain of the involved ankle within 3 months prior to study enrollment
  • A History of lower-extremity surgery or fracture
  • A history of neurological disorder
  • The presence of cardiopulmonary disorder
  • Self-reported symptoms of cybersickness
  • Left-handedness

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

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Diaphragmatic brathing Training group

Participants in this group received diaphragmatic breathing training in a single session. Outcomes, including cortical activity, EEG indices, diaphragm contractility, dynamic balance, and ankle instability, were assessed before and immediately after the session.
Behavioral: Diaphragmatic Breathing Training

Participants assigned to this intervention will perform diaphragmatic breathing training in a single session. Participants will be guided to breathe using the diaphragm, and the training will be delivered under the supervision of a trained researcher.
Experimental: VR-based breathing meditation group

Participants in this group received breathing meditation delivered through a virtual reality environment in a single session. Outcomes, including cortical activity, EEG indices, diaphragm contractility, dynamic balance, and ankle instability, were assessed before and immediately after the session.
Behavioral: VR-based Breathing Meditation

Participants assigned to this intervention will perform breathing meditation delivered through a virtual reality environment in a single session. Participants will wear a VR headset and follow the breathing meditation content presented in the virtual environment.
Experimental: Neurofeedback relaxation training group

Participants in this group received brain relaxation training based on EEG neurofeedback in a single session. Outcomes, including cortical activity, EEG indices, diaphragm contractility, dynamic balance, and ankle instability, were assessed before and immediately after the session.
Behavioral: Neurofeedback Brain Relaxation Training

Participants assigned to this intervention will perform brain relaxation training based on EEG neurofeedback in a single session. Participants will receive real-time feedback on their EEG activity and will be trained to achieve a relaxed brain state.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change in dorsolateral prefrontal cortex oxygenated hemoglobin (HbO2) concentration measured by fNIRS
Time Frame: Baseline (before the intervention) and immediately after the single intervention session

Oxygenated hemoglobin (HbO2) concentration was measured by functional near-infrared spectroscopy (fNIRS) in the dorsolateral prefrontal cortex. Change was calculated as the difference between pre- and post-intervention values.
Baseline (before the intervention) and immediately after the single intervention session
Change in frontopolar cortex oxygenated hemoglobin (HbO2) concentration measured by fNIRS
Time Frame: Baseline (before the intervention) and immediately after the single intervention session

Oxygenated hemoglobin (HbO2) concentration was measured by functional near-infrared spectroscopy (fNIRS) in the frontopolar cortex. Change was calculated as the difference between pre- and post-intervention values.
Baseline (before the intervention) and immediately after the single intervention session
Change in orbitofrontal cortex oxygenated hemoglobin (HbO2) concentration measured by fNIRS
Time Frame: Baseline (before the intervention) and immediately after the single intervention session

Oxygenated hemoglobin (HbO2) concentration was measured by functional near-infrared spectroscopy (fNIRS) in the orbitofrontal cortex. Change was calculated as the difference between pre- and post-intervention values.
Baseline (before the intervention) and immediately after the single intervention session
Change in medial prefrontal cortex oxygenated hemoglobin (HbO2) concentration measured by fNIRS
Time Frame: Baseline (before the intervention) and immediately after the single intervention session

Oxygenated hemoglobin (HbO2) concentration was measured by functional near-infrared spectroscopy (fNIRS) in the medial prefrontal cortex. Change was calculated as the difference between pre- and post-intervention values.
Baseline (before the intervention) and immediately after the single intervention session
Change in EEG delta band power
Time Frame: Baseline (before the intervention) and immediately after the single intervention session

Delta band (0.5-4 Hz) power was measured by electroencephalography (EEG) at [electrode site(s)]. Change was calculated as the difference between pre- and post-intervention values. Unit: [µV²].
Baseline (before the intervention) and immediately after the single intervention session
Change in EEG theta band power
Time Frame: Baseline (before the intervention) and immediately after the single intervention session

Theta band (4-8 Hz) power was measured by electroencephalography (EEG) at [electrode site(s)]. Change was calculated as the difference between pre- and post-intervention values. Unit: [µV²].
Baseline (before the intervention) and immediately after the single intervention session
Change in EEG alpha band power
Time Frame: Baseline (before the intervention) and immediately after the single intervention session

Alpha band (8-12 Hz) power was measured by electroencephalography (EEG) at [electrode site(s)]. Change was calculated as the difference between pre- and post-intervention values. Unit: [µV²].
Baseline (before the intervention) and immediately after the single intervention session
Change in EEG sensorimotor rhythm (SMR) band power
Time Frame: Baseline (before the intervention) and immediately after the single intervention session

Sensorimotor rhythm (SMR) band (12-15 Hz) power was measured by electroencephalography (EEG) at [electrode site(s)]. Change was calculated as the difference between pre- and post-intervention values. Unit: [µV²].
Baseline (before the intervention) and immediately after the single intervention session
Change in EEG beta band power
Time Frame: Baseline (before the intervention) and immediately after the single intervention session

Beta band (15-30 Hz) power was measured by electroencephalography (EEG) at [electrode site(s)]. Change was calculated as the difference between pre- and post-intervention values. Unit: [µV²].
Baseline (before the intervention) and immediately after the single intervention session

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in diaphragm thickening fraction measured by ultrasound
Time Frame: Baseline (before the intervention) and immediately after the single intervention session

Diaphragm thickness was measured by ultrasound at end-inspiration and end-expiration, and the diaphragm thickening fraction was calculated as (end-inspiration thickness - end-expiration thickness) / end-expiration thickness × 100 (%). Change was calculated as the difference between pre- and post-intervention values.
Baseline (before the intervention) and immediately after the single intervention session
Change in dynamic balance measured by the Star Excursion Balance Test (SEBT)
Time Frame: Baseline (before the intervention) and immediately after the single intervention session

Dynamic balance was assessed by the Star Excursion Balance Test (SEBT), in which participants reached as far as possible with the free limb while standing on the affected limb. Reach distance was measured in each direction, and change was calculated as the difference between pre- and post-intervention values.
Baseline (before the intervention) and immediately after the single intervention session
Change in ankle instability measured by CAIT-K
Time Frame: Baseline (before the intervention) and immediately after the single intervention session

Ankle instability was assessed using [instrument name]. Change was calculated as the difference between pre- and post-intervention scores.
Baseline (before the intervention) and immediately after the single intervention session

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Gwangju Health University

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 14, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
February 14, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
March 30, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 4, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 11, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 13, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
November 13, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 11, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2026

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • P01-202610-01-075

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

De-identified individual participant data underlying the results reported in the publication will be shared with qualified researchers upon reasonable request to the corresponding author. Data will be available after publication of the main results.

IPD Sharing Time Frame

Data will be available beginning 6 months after publication of the main results

IPD Sharing Access Criteria

Qualified researchers may request access to de-identified individual participant data by contacting the corresponding author. Requests will be reviewed by the research team, and data will be shared for academic research purposes.

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • ICF

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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