Reduced Volume of Inspiratory Resistance Training (REVIRT)

Maintenance Dose of Inspiratory Muscle Strength Training to Preserve Cardiovascular Adaptations

This clinical research study will investigate the dose of inspiratory muscle strength training needed to maintain cardiovascular adaptations induced by a six-week loading dose.

Study Overview

• Status: Not yet recruiting
• Conditions: Hypertension
• Intervention / Treatment: Behavioral: Inspiratory muscle strength training

Detailed Description

Cardiovascular disease (CVD) is the leading cause of death in the US and worldwide. Although it is well-known that lifestyle changes (e.g., diet, exercise) lower blood pressure (BP) and risk for cardiovascular events, an estimated ~98% of US adults with above-normal BP do not adhere to the recommended lifestyle behaviors. Common barriers to exercise, including lethargy, low exercise self-efficacy, fear of exercise-related pain, and lack of time, make adherence to traditional exercise strategies particularly difficult. The need for novel/different forms of exercise that are i) time-efficient, ii) well-tolerated, and iii) effective has never been greater.

Inspiratory muscle strength training (IMST) is a novel, time-efficient respiratory exercise, comprising just 5 sets of 6 inspiratory efforts with 1-minute rests between sets. This training takes just 5 mins/day, 5 sessions/wk, for a total weekly training time of 25-30 minutes. Distinct from other forms of traditional aerobic or high-intensity interval-type exercise, IMST is performed on a hand-held device in sitting or standing. Participants make repeated inspiratory efforts against a resistance and generate large negative pressures that are 2-4-fold greater than those generated during rest breathing, deep breathing, or high-intensity aerobic exercise. The investigators have shown that IMST performed 5 days/wk for 6 weeks, lowers SBP 9 ± 1 mmHg on average.

It is well known that exercise-induced adaptations plateau over time, despite increases in volume and/or intensity. Accordingly, the goal of exercise is not only to improve health, but to maintain health adaptations long term. Importantly, the dose of exercise required to improve health/performance is higher than the dose required to maintain health/performance. Given that lack of time is the most often cited reason for adults failing to initiate exercise and stopping chronic exercise participation, it is essential that any potential participant 1) appreciate the relationship between time spent exercising and health improvements and 2) understand how much exercise is needed to preserve exercise-induced adaptations to ensure an unnecessary amount of time is devoted to exercise. The investigators have shown that 6 weeks of IMST can significantly lower BP and improve respiratory strength, however, the dose needed to preserve these adaptations is unknown.

This study comprises a 6-week loading dose of IMST (5 days/week; Endpoint 1), followed by 12 weeks of IMST at a reduced dose (0, 1, or 3 days/week; Endpoint 2).

• Study Type: Interventional
• Enrollment (Estimated): 36
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Dallin Tavoian, PhD; Phone Number: 5206210388; Email: tavoian@arizona.edu

Study Locations

• United States
  • Arizona
    • Tucson, Arizona, United States, 85724
      • Arizona Respiratory and Neurophysiology Laboratory
      • Contact: Dallin Tavoian, PhD; Phone Number: 520-621-0388; Email: tavoian@arizona.edu
      • Principal Investigator: Dallin Tavoian, PhD
      • Sub-Investigator: Elizabeth F Bailey, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 50 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• 50+ years of age
• systolic blood pressure between 120-169 mmHg
• stable dose of medication (three months on the same dose)
• weight stable in the prior 3 months (<3.0 kg weight change) and willing to remain weight stable throughout the study
• absence of unstable clinical disease as determined by medical history
• owns a smartphone

Exclusion Criteria:

• current smoker (including tobacco products, vaping devices, THC, etc…)
• have an uncontrolled medical condition (e.g., cancer)
• myocardial infarction or stroke within the previous 12 months
• performs regular aerobic exercise (>4 bouts/week)
• BMI ≥ 40 kg/m2
• systolic blood pressure <120 or ≥170 mmHg
• diastolic blood pressure >100 or <60 mmHg
• Cheyne-Stokes respiration
• history of perforated eardrum
• history of glaucoma or retinopathy
• history of collapsed lung
• diagnosed with asthma
• pregnant, breastfeeding, or trying to become pregnant (self-reported)
• medications that, in the opinion of the study physician, may impact the outcomes of the study (e.g., steroids)
• does not own a smartphone or is unwilling to download the required application

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Control; 30 breaths/day (5 sets of 6 breaths, one minute of rest between sets), 5 days/week, for 6 weeks, then no exercise for 12 weeks
Experimental: IMST 1 day/week; 30 breaths/day (5 sets of 6 breaths, one minute of rest between sets), 5 days/week, for 6 weeks, then 30 breaths/day (5 sets of 6 breaths, one minute of rest between sets), 1 day/week, for 12 weeks.	Behavioral: Inspiratory muscle strength training; 30 breaths/day against a set resistance
Experimental: IMST 3 days/week; 30 breaths/day (5 sets of 6 breaths, one minute of rest between sets), 5 days/week, for 6 weeks, then 30 breaths/day (5 sets of 6 breaths, one minute of rest between sets), 3 days/week, for 12 weeks.	Behavioral: Inspiratory muscle strength training; 30 breaths/day against a set resistance

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline to endpoint 1 (6 weeks) resting systolic blood pressure	Systolic blood pressure (SBP) will be measured by absolute change from baseline. SBP will be assessed in accordance with American College of Cardiology/American Heart Association guidelines. Measurements will be taken using an automated oscillometric sphygmomanometer and will be performed in triplicate over the brachial artery of the left arm after 5 minutes of quiet rest, with 1 minute of recovery between measures. SBP will be defined as the average of the 3 pressures.	Blood pressure will be assessed at baseline and after 6 weeks of training
Change from endpoint 1 (6 weeks) to endpoint 2 (+12 weeks) resting systolic blood pressure	Systolic blood pressure (SBP) will be measured by absolute change from endpoint 1. SBP will be assessed as described in Outcome 1.	Blood pressure will be assessed after 6 weeks of training and after an additional 12 weeks of training
Change from baseline to endpoint 1 (6 weeks) Nitric Oxide-mediated Endothelium Dependent Dilation (EDD)	Brachial artery Flow Mediated Dilation (BA-FMD), a well-established measure of NO-mediated endothelial function, will be measured by both relative and absolute changes from baseline. BA-FMD will be determined using high-resolution ultrasonography and analyzed with a commercially available software package. An ultrasound probe will be placed 3-6 cm proximal to the antecubital crease on the right arm and a baseline image of the right brachial artery will be obtained. Following baseline, reactive hyperemia will be produced by inflating a rapid-inflating blood pressure cuff. Brachial artery diameter change will be measured for 2 minutes following 5-min of forearm blood flow occlusion.	EDD will be assessed at baseline and after 6 weeks of training
Change from endpoint 1 (6 weeks) to endpoint 2 (+12 weeks) Nitric Oxide-mediated Endothelium Dependent Dilation (EDD)	EDD will be assessed as described in Outcome 3	EDD will be assessed after 6 weeks of training and after an additional 12 weeks of training

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline to endpoint 1 (6 weeks) cerebrovascular reactivity (CVR)	CVR will be assessed via changes in middle cerebral artery (MCA) blood velocitywill be assessed in a reclined sitting position while breathing room air and again after 4 min of breathing a medical gas mixture with 5 % CO2 l to elicit vasodilation. A transcranial Doppler probe will be placed over the subject's temple to obtain a velocity tracing from the middle cerebral artery. After a tracing of MCA velocity is obtained and baseline measurements are recorded (while breathing room air), the subject will then switch over to breathing 5% CO2 for	CVR will be assessed at baseline and after 6 weeks of training
Change from endpoint 1 (6 weeks) to endpoint 2 (+12 weeks)	CVR will be assessed as described in Outcome 5	CVR will be assessed after 6 weeks of training and after an additional 12 weeks of training

Collaborators and Investigators

• Sponsor: University of Arizona
• Collaborators: American Heart Association
• Investigators: Principal Investigator: Dallin Tavoian, PhD, University of Arizona

Study record dates

Study Major Dates

• Study Start (Estimated): January 15, 2024
• Primary Completion (Estimated): December 1, 2024
• Study Completion (Estimated): March 1, 2025

Study Registration Dates

• First Submitted: February 15, 2023
• First Submitted That Met QC Criteria: February 15, 2023
• First Posted (Actual): February 27, 2023

Study Record Updates

• Last Update Posted (Actual): November 29, 2023
• Last Update Submitted That Met QC Criteria: November 28, 2023
• Last Verified: February 1, 2023

More Information

Terms related to this study

• Keywords: blood pressure; non-pharmacological; vascular endothelium; inspiratory resistance training
• Additional Relevant MeSH Terms: Pathologic Processes; Respiratory Tract Diseases; Respiration Disorders; Respiratory Aspiration
• Other Study ID Numbers: 00002581

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