Smartphone App-guided Inspiratory Muscle Strength Training for Lowering Systolic Blood Pressure

April 27, 2026 updated by: Douglas Seals, University of Colorado, Boulder
This clinical trial aims to assess the efficacy of inspiratory muscle strength training (IMST) guided by a smartphone app vs. IMST delivered in a clinical research setting for lowering systolic blood pressure in adults 18 years and older with elevated blood pressure. Participants will perform IMST for 5 minutes a day, 6 days a week, for 6 weeks.

Study Overview

Status

Status

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

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

Having above-normal blood pressure, i.e., ≥120 mmHg systolic blood pressure (SBP) and/or ≥80 mmHg diastolic blood pressure (DBP), increases risk of developing cardiovascular diseases, cognitive decline/dementia, chronic kidney disease, and other chronic health problems. Approximately 60% of all US adults have above-normal BP, primarily driven by above-normal SBP.

Currently, above-normal SBP is the single largest modifiable risk factor for cardiovascular mortality in the United States. Thus, developing novel strategies for lowering SBP is an urgent public health and biomedical research priority.

Guidelines emphasize regular aerobic exercise as a first-line intervention for all stages of above-normal systolic blood pressure (SBP). Current guidelines call for ≥150 minutes of aerobic activity per week. However, only ~50% of US adults meet these aerobic exercise guidelines. The greatest reported barrier to achieving aerobic exercise guidelines is lack of time. High-resistance inspiratory muscle strength training (IMST) is a time-efficient (5 minutes per session) lifestyle intervention consisting of 30 inspiratory maneuvers performed against a high resistance. Preliminary data suggest 6-weeks of IMST performed 6 days/week reduces SBP by 9 mmHg in adults with above-normal SBP (i.e., greater than 120 mmHg) at baseline. Importantly, this reduction in SBP is equal to or greater than the reduction in blood pressure typically achieved with time- and effort-intensive healthy lifestyle strategies like conventional aerobic exercise.

The investigators hope utilizing a smartphone app to guide IMST will promote the translation of IMST for widespread use and improving public health. The investigators will conduct a randomized, controlled, single-blind, parallel group design clinical trial to assess the efficacy of 6-weeks of IMST (55%-75% maximal inspiratory pressure) delivered in the research clinic by the study investigators vs. IMST delivered entirely via a smartphone app without investigator involvement, for lowering resting and home SBP in adults aged 18 years and older with above-normal SBP (120-160 mmHg) at baseline. The investigators will also assess the effect of IMST on endothelial function, large-elastic artery stiffness, and potential mechanisms of action.

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 (Actual)

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 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

  • United States
    • Colorado
      • Boulder, Colorado, United States, 80309
        • University of Colorado Boulder

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
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Age 18+ years
  • Ability to provide informed consent
  • Willing to accept random assignment to condition
  • Systolic blood pressure 120-160 mmHg
  • Owns an Apple or Android smartphone
  • Body mass index <40 kg/m2
  • Subject report of being weight stable in the prior 3 months (<2 kg weight change) and willing to remain weight stable during the 6-week intervention period
  • Subjects taking antihypertensive medications will be included provided they meet the other inclusion criteria, including systolic blood pressure. Medication regimen (prescription and dosing) must be stable for at least 3 months prior to enrollment in the study and must remain stable during the 6-week intervention period. These medications will not be withheld prior to experimental protocols.

  • If woman of childbearing age:

    • Not pregnant (defined as self-report of pregnancy)
    • Willing to be abstinent or use approved contraception (i.e., hormonal contraception, intrauterine devices, barrier methods such as condoms with spermicide, and surgical sterilization) throughout the duration of the study

Exclusion Criteria:

  • Age <18 years
  • Participant report of a chronic overt medical condition (e.g., unstable cardiovascular disease, recent myocardial infarction or stroke, cancer) that may make it unsafe to participate in the study under the discretion of the study Medical Director.
  • Inability to abstain from consumption of alcohol for 12 hours on experimental days.
  • Report of blood donation within 8 weeks prior to enrolling in the study or unwillingness to abstain from donating blood for 8 weeks after completing the study
  • Participant report of current ruptured eardrum or any other current condition of the ear
  • Participant report of recent abdominal surgery (past 3 months) or current abdominal hernia
  • Participant report of current asthma with very low symptom perception, frequent and severe exacerbations, or abnormally low perception of dyspnea
  • Participant report of past or current costochondritis (inflammation of the cartilage that joins the ribs to the breastbone)

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: 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.
Experimental: App-Based Inspiratory Muscle Strength Training
Using a handheld device, participants will perform 30 breaths a day, six days a week, for six weeks. Training will be guided by a smartphone application.
Device: App-Based Inspiratory Muscle Strength Training
Participants will perform inspiratory muscle strength training guided by a smartphone application. Participants will perform 30 breaths a day at 75% of maximal inspiratory pressure, 6 days a week, for 6 weeks. All training sessions will be guided by the smartphone application.
Active Comparator: Clinic-Based Inspiratory Muscle Strength Training
Using a handheld device, participants will perform 30 breaths a day, six days a week, for six weeks. Training will be guided by researchers.
Device: Clinic-Based Inspiratory Muscle Strength Training
Participants will perform inspiratory muscle strength training guided by researchers. Participants will perform 30 breaths a day at 75% of maximal inspiratory pressure, 6 days a week, for 6 weeks. One training session each week will be performed in the research clinic.

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 Casual Systolic Blood Pressure
Time Frame: 6 weeks
Change in systolic blood pressure at rest in the clinic setting
6 weeks
Change From Baseline in Home Systolic Blood Pressure
Time Frame: 6 weeks
Change in systolic blood pressure measured at rest in the home
6 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
Change From Baseline in Endothelial Function
Time Frame: 6 weeks
A procedure called brachial artery flow-mediated dilation will be used to assess endothelium-dependent vasodilation. During this procedure a blood pressure cuff will be placed on the forearm and then inflated for 5 minutes to restrict blood flow. During the procedure a video of the brachial artery will be taken with an ultrasound. The video will be analyzed to determine the peak change in the blood vessels diameter. Blood flow response after cuff deflation will also be assessed.
6 weeks
Change From Baseline in Maximum Inspiratory Pressure
Time Frame: 6 weeks
Participants will use a hand-held breathing device to assess their maximum inspiratory pressure once a week during the intervention. During the maximum inspiratory pressure test, participants will inspire into the device as powerfully as they can. Results from the maximum inspiratory pressure tests will be assessed.
6 weeks
Difference in Adherence to Inspiratory Muscle Strength Training
Time Frame: 6 weeks
Percentage of days performing inspiratory muscle strength training during the intervention between each group
6 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 Colorado, Boulder

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: Daniel H Craighead, PhD, University of Colorado, Boulder

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.
June 27, 2024

Primary Completion (Actual)

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.
December 31, 2025

Study Completion (Actual)

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.
December 31, 2025

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).
January 16, 2024

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.
January 26, 2024

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.
January 29, 2024

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 19, 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.
April 27, 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.
April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

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.
  • 23-0411

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

Yes

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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