High-Intensity Progressive Inspiratory Muscle Training in Class III Obesity and Obstructive Sleep Apnea

March 18, 2026 updated by: Karina Abreu, University of the State of Santa Catarina

High-Intensity Progressive Inspiratory Muscle Training in Class III Obesity and Obstructive Sleep Apnea: Study Protocol for a Prospective Nonconcurrent Multiple-Baseline Single-Case Experimental Design With Stability-Based Phase Transition

The purpose of this study is to evaluate the feasibility and effects of a 12-week high-intensity progressive Inspiratory Muscle Training (IMT) program in individuals with Class III obesity (BMI ≥ 40 kg/m²) and obstructive sleep apnea (OSA). Using a single-case experimental design (SCED) with multiple baselines, the study will investigate whether this respiratory intervention can reduce the severity of sleep apnea, as measured by the Apnea-Hypopnea Index (AHI), and improve inspiratory muscle strength and sleep quality. Participants will perform daily training sessions using a resistive loading device (POWERbreathe), with intensity progressing from 40% to 90% of their maximum inspiratory pressure.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

10

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 Contact

Study Contact Backup

Study Locations

  • Brazil
    • Santa Catarina
      • Florianópolis, Santa Catarina, Brazil, 88080-350
        • Santa Catarina State University - CEFID (Center of Health and Sport Sciences)
        • 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

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria: -Adults (≥18 years).

  • Of both genders.
  • Class III obesity (BMI > 40 kg/m²).
  • Diagnosis of OSA.
  • Without neurological conditions that would prevent them from responding to the study assessments.

Exclusion Criteria:

  • Systemic diseases (pulmonary, cardiac or renal).
  • Are using medications that may affect muscle performance.
  • Are currently using CPAP therapy.
  • Conditions that could compromise adherence to the study protocol.

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: Treatment
  • Allocation: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Experimental Group: High-Intensity IMT
Participants will undergo a progressive high-intensity Inspiratory Muscle Training (IMT) program using a resistive loading device (POWERbreathe).
Device: High-Intensity Progressive Inspiratory Muscle Training (IMT)
"The intervention consists of 12 weeks of inspiratory muscle training performed 5 days per week. Each session includes 30 breaths through a resistive loading device (POWERbreathe). The training intensity starts at 40% of the Maximum Inspiratory Pressure (MIP) and progressively increases to 90% of MIP. Training load is adjusted weekly based on new MIP measurements to ensure high-intensity stimulus. Compliance and adverse events will be monitored through a training diary."

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Apnea-Hypopnea Index (AHI)
Time Frame: Baseline (Phase A - three measurements) and Post-Intervention (Phase B - 12th week).
Number of apnea and hypopnea events per hour of sleep, measured via portable polygraphy (Type III)
Baseline (Phase A - three measurements) and Post-Intervention (Phase B - 12th week).

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Maximum Inspiratory Pressure (MIP)
Time Frame: Weekly assessments throughout Phase A (3 to 5 weeks) and Phase B (12 weeks).
Assessment of inspiratory muscle strength using a digital pressure manometer.
Weekly assessments throughout Phase A (3 to 5 weeks) and Phase B (12 weeks).
Epworth Sleepiness Scale (ESS) score
Time Frame: Baseline and Post-Intervention (12th week).
Validated questionnaire to assess the level of daytime sleepiness. Scores range from 0 to 24, where higher scores indicate greater sleepiness.
Baseline and Post-Intervention (12th week).
Pittsburgh Sleep Quality Index (PSQI) global score
Time Frame: Baseline and Post-Intervention (12th week).
Questionnaire to assess sleep quality over a one-month period. Scores range from 0 to 21; higher scores indicate poorer sleep quality.
Baseline and Post-Intervention (12th week).
International Physical Activity Questionnaire (IPAQ) - Short Form
Time Frame: Baseline and Post-Intervention (12th week).
Assessment of physical activity level. It classifies participants as sedentary, irregularly active, active, or very active based on metabolic equivalent task (MET-min/week).
Baseline and Post-Intervention (12th week).
Borg Rating of Perceived Exertion (RPE)
Time Frame: Daily during the 12 weeks of intervention (Phase B).
Scale ranging from 6 to 20 used to monitor the intensity of the respiratory effort during the IMT sessions.
Daily during the 12 weeks of intervention (Phase B).
Quebec Sleep Questionnaire (QSQ)
Time Frame: Baseline (Phase A) and Post-Intervention (12th week of Phase B).
A disease-specific quality of life questionnaire for obstructive sleep apnea. It consists of 32 items divided into five domains: daytime sleepiness, diurnal symptoms, nocturnal symptoms, emotions, and social interactions. Each item is scored on a 7-point Likert scale, where higher scores indicate better quality of life.
Baseline (Phase A) and Post-Intervention (12th week of Phase B).

Collaborators and Investigators

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

Sponsor

University of the State of Santa Catarina

Investigators

  • Study Chair: Darlan Laurício Matte, PhD, Santa Catarina State University (UDESC)

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)

May 1, 2026

Primary Completion (Estimated)

May 1, 2027

Study Completion (Estimated)

December 1, 2027

Study Registration Dates

First Submitted

March 9, 2026

First Submitted That Met QC Criteria

March 9, 2026

First Posted (Actual)

March 13, 2026

Study Record Updates

Last Update Posted (Actual)

March 23, 2026

Last Update Submitted That Met QC Criteria

March 18, 2026

Last Verified

March 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • CAAE86299625.1.0000.0118

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

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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