Effects of Isocapnic Respiratory Muscle Endurance Training in Healthy Adults

May 13, 2026 updated by: Jordan Guenette, University of British Columbia

The Effects of Isocapnic Respiratory Muscle Endurance Training on the Multidimensional Components and Neurophysiological Mechanisms of Exertional Breathlessness in Healthy Adults

Respiratory muscle training (RMT) strengthens breathing muscles and may improve exercise performance and reduce breathlessness. However, different training methods and devices create controversy in the field. Two main types of RMT exist: inspiratory muscle training (IMT) and respiratory endurance training, like voluntary isocapnic hyperpnea (VIH). While IMT is well-studied, the impact of VIH on breathlessness remains unclear. This study will use the Canadian-developed BreathWayBetter device to examine how 5 weeks of VIH affects breathing discomfort and muscle function. Findings may help personalize RMT for athletes and clinical patients, improving respiratory care and exercise tolerance.

Study Overview

Status

Status

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

Conditions

Conditions

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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

Purpose: to determine the effect of voluntary isocapnic hyperpnea (VIH) respiratory muscle training (RMT) using the BreathWayBetter training device on the multidimensional components of dyspnoea, as well as exercise performances measures.

Objectives and Hypothesis:

Objective 1: The first primary objective is to examine the effects of the BreathWayBetter (BWB) training device on the intensity and unpleasantness of dyspnoea during exercise, and to determine what sensory qualities of dyspnoea are primarily affected.

Hypothesis 1: Change in dyspnea intensity (pre vs post training) will be the same in the sham and training group, however, the reduction in dyspnea unpleasantness will be significantly greater in the training group. The training group will also have a greater reduction in breathlessness-related emotional ratings compared to the sham group.

Objective 2: The second primary objective is to examine the effects of the BreathWayBetter (BWB) training device on peak oxygen consumption (VO2peak) during the pre and post intervention incremental cycle exercise tests in both conditions.

Hypothesis 2: Change in VO2peak (pre vs post training) will be greater in the training group compared to sham group.

Objective 3: The secondary objective is to explore the relationship between exercise performance and the subjective perception of dyspnoea following training.

Hypothesis 3: The magnitude of change in exercise performance will be moderately correlated with the magnitude of change in dyspnoea in the training group.

Justification:

Respiratory muscle training (RMT) is a collection of techniques designed to enhance respiratory muscle function through improvements in strength and endurance. While several reviews state that RMT has been shown to improve exercise performance, respiratory muscle strength, and dyspnoea ratings, it remains a contentious field of research. This controversy may be driven, at least in part, due to the wide variation of training devices and protocols used throughout the literature. Two predominant forms of RMT are typically used in healthy adults, respiratory muscle strength training and respiratory muscle endurance training. The former, more commonly referred to as inspiratory muscle training (IMT), incorporates breathing against resistive loading, while the latter uses isocapnic hyperpnoea as a training stimulus.

Respiratory muscle endurance training in the form of voluntary isocapnic hyperpnea (VIH) requires individuals to perform purposeful breathing at a target frequency and depth to maintain over a set duration. In contrast to the high-force, and often unidirectional demands of respiratory strength training, VIH consists of low-force, high-velocity contractions of inspiratory and expiratory muscles, which may be more relevant breathing patterns for endurance sports such as running and cycling. However, previous research has largely focused on the use of IMT on sports performance and respiratory muscle strength. Interestingly, given the notable positive effect on respiratory muscle strength, the use of RMT to alleviate dyspnoea, or breathlessness has been poorly studied. Several studies have reported decreases in ratings of perceived breathlessness during exercise following IMT. However, these studies employed unidimensional measurements that capture only the overall severity of dyspnoea, lacking a qualitative assessment of its intensity, unpleasantness, or emotional response necessary for a comprehensive understanding of dyspnoea in response to VIH training.

While previous literature is sparse, several studies have suggested that reductions in perceptual ratings may provide insight into the etiology of the ergogenic effect of RMT. RMT may result in a delayed onset of respiratory muscle fatigue and subsequently attenuate the respiratory muscle metaboreflex at high intensities. This reflex reduces blood flow to the peripheral locomotor muscles in favour of redirection to the respiratory muscles. Therefore a reduction in competitive blood flow and improved lactate clearance may provide reasoning for the lower perceived exertion of the limb muscles and breathing discomfort ratings observed. It may be further suggested that reduced respiratory muscle fatigue stems from an improved aerobic capacity of the primary and accessory muscles due to RMT. Therefore, it is plausible that VIH RMT may reduce the energy cost of breathing and/or improve peripheral limb oxygenation, which subsequently may lessen the intensity and quality of exertional dyspnoea sensations. Lastly, VIH RMT may also lead to desensitization to continuous loading of the respiratory muscles and diminish the perception of dyspnoea, specifically in the affective dimension (i.e., unpleasantness and emotion).

There are no studies that have assessed the multidimensional components of dyspnoea following respiratory muscle endurance training (i.e., VIH) nor the physiological outcome measures that may be linked to improvements in the intensity and quality of dyspnoea. Accordingly, the investigators have designed a study that will perform a multidimensional analysis of dyspnoea to provide a more comprehensive understanding of the immediate perception and emotional response to VIH RMT.

The Isocapnic BreathWayBetter (Isocapnic Technologies Inc, Kelowna, Canada) is a commercially available, affordable, portable device, paired with the free user-friendly app that allows for personalized VIH training programs with visual guidance that can be performed anywhere. However, its efficacy in improving measures of perceptual responses, such as the distressing qualities of dyspnoea (e.g., unsatisfied inspiration) following a prolonged training regimen remains unknown. Therefore, the primary aim of this study is to investigate the effects of 5 weeks of respiratory endurance training with the BWB device on the multidimensional components of breathlessness.

Statistical analysis:

The normality of the data will be tested using the Shapiro-Wilk test. A two-way mixed analysis of variance (ANOVA) will be performed to assess whether there are significant differences in pre and post-test measures of Borg dyspnoea ratings and selected respiratory measurements at standardized exercise times. Additionally, this will assess if the changes from pre and post-intervention measures differ between the control and intervention groups. Peak exercise data (final 30 seconds) will be compared within groups with paired t-tests and between groups with independent t-tests. Spearman's correlation coefficients will be used to examine the association between change in exercise time and dyspnoea scores. In all cases, a P value < 0.05 will be considered statistically significant. All data will be presented as means ± standard deviation (SD).

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.
32

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 Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • Canada
    • British Columbia
      • Vancouver, British Columbia, Canada, V6Z 1Y6
        • Recruiting
        • St. Paul's Hospital
        • Contact:
        • Principal Investigator:
          • Jordan Guenette, PhD

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

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • 18-55 years of age (inclusive)
  • Male or Female (biological sex)
  • Body mass index greater than 18 or less than 30 kg/m2
  • Normal pulmonary function: FEV1/FVC > 0.70 and FEV1 ≥ 80%
  • Able to read and understand English
  • Regularly trains and/or competes at a regional, national, or international level as a road cyclist or triathlete
  • Access to a device with the capability to download the Isocapnic app (Apple IOS or Google Play/Android) or the ability to use the Web Based application.

Exclusion Criteria:

  • Currently smoke, vape, or use cannabis, or have a history of frequent smoking, vaping or cannabis use
  • History of, or current symptoms of cardiopulmonary (i.e., lung and/or heart) disease (excluding controlled asthma)
  • Heart problem; a serious infection within the body; a neuromuscular (nerve to muscle) or musculoskeletal (muscle, ligament and/or bone) disorder; or other health problem that will be made worse with exercise testing
  • Contraindications to exercise testing defined as anything that would prevent exercise under proper and safe conditions (e.g. a problem with the heart or lungs, muscle or bone injury, a serious infection)
  • Currently pregnant
  • Required to read and understand English due to the nature of the consent form and study materials, including questionnaires and training instructions, which are only available in English.

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: Double

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.
Sham Comparator: Low frequency and intensity training
Participant will perform a respiratory training following a low intensity and frequency protocol
Other: Sham respiratory muscle endurance training
Respiratory muscle endurance training program over 5 weeks following a sham training procedure that is meant to elicit no physiologic changes.
Active Comparator: Progressive high frequency and intensity training
Participant will perform a respiratory training following a progressive intensity and frequency protocol
Other: Respiratory muscle endurance training
Respiratory muscle endurance training program over 5 weeks.

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 from baseline in dyspnoea ratings on the 0-10 Borg scale after respiratory endurance training
Time Frame: Up to 7 weeks
Dyspnoea ratings on the 0-10 Borg scale will be recorded during and after incremental cardiopulmonary exercise testing on a stationary cycle ergometer. Dyspnoea ratings will then be compared between the pre- and post-intervention visits.
Up to 7 weeks
Difference in maximal oxygen consumption (VO2peak) following high intensity training program compared to sham comparator program.
Time Frame: Up to 7 weeks
Changes in peak oxygen consumption (VO2peak) will be measured during an incremental cardiopulmonary exercise test on a stationary cycle ergometer and compared between intervention conditions.
Up to 7 weeks

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
Correlation between changes from baseline in maximal oxygen consumption (VO2peak) and changes from baseline in dyspnoea ratings on the 0-10 Borg scale following respiratory endurance training.
Time Frame: Up to 7 weeks
Peak oxygen consumption (VO2peak) in units of ml/kg/min and dyspnoea ratings measured on the 0-10 Borg scale will be measured during an incremental cardiopulmonary exercise test on a stationary cycle ergometer and compared between the pre- and post-intervention visits.
Up to 7 weeks

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.
University of British Columbia

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Mitacs

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Jordan Guenette, PhD, University of British Columbia

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 (Actual)

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.
August 4, 2025

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.
August 1, 2026

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.
August 1, 2026

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).
July 10, 2025

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.
July 31, 2025

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.
August 5, 2025

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.
May 15, 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.
May 13, 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.
May 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.
  • H25-00744

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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