Blood Pressure Following Isometric Exercise in Inactive Adults (BELIEF-BP)

May 15, 2025 updated by: Canterbury Christ Church University

Beliefs and Expectation Effects on Blood Pressure Following Isometric Exercise in Inactive Adults

This study investigates how isometric exercise training (IET) affects blood pressure in physically inactive adults. Isometric exercise involves sustained muscle contractions without movement-for example, pushing against a fixed object. Previous research has shown that IET may help reduce blood pressure, but the mechanisms involved are not fully understood.

The purpose of this study is to assess both the immediate (acute) and long-term (chronic) effects of IET on cardiovascular outcomes. Participants will complete a series of lab-based exercise sessions over several weeks. In these sessions, they will perform repeated bouts of isometric leg extensions while seated on an exercise machine designed to measure muscle force.

Throughout the study, researchers will monitor participants' blood pressure, heart rate, and muscle activity. Acute responses-such as post-exercise hypotension (a short-term drop in blood pressure)-will be measured immediately after exercise. Chronic changes, such as resting blood pressure improvements, will be evaluated across the training period.

Additional measurements will include heart rate variability (HRV), which gives insight into autonomic nervous system activity, and electromyography (EMG), which tracks muscle fatigue and activation patterns. These data will help explore potential mechanisms behind the cardiovascular benefits of IET.

By examining how repeated sessions of isometric exercise influence blood pressure and related physiological responses, this research may support the use of IET as a non-pharmacological strategy for managing or preventing hypertension in physically inactive individuals.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

36

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

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

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Age 18 years or older
  • Self-reported physically inactive or insufficiently active (not meeting current physical activity guidelines)
  • Not currently engaged in structured resistance or isometric exercise training
  • Able to attend lab sessions over a 4-week period
  • Provides written informed consent

Exclusion Criteria:

  • Current diagnosis of hypertension requiring medication
  • Any known cardiovascular, neurological, or musculoskeletal condition contraindicating isometric exercise
  • Formal education or professional background in exercise science, physiology, or a related field
  • Pregnant or planning to become pregnant during the study period
  • Inability to follow verbal instructions or complete study protocols

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
Intervention / Treatment
Experimental: Neutral Information + Isometric Exercise
Participants in this group complete repeated isometric exercise training sessions. Prior to training, they receive a neutral informational presentation about isometric exercise, which does not mention blood pressure or cardiovascular benefits. The exercise consists of bilateral isometric leg extensions on a dynamometer. Cardiovascular and neuromuscular outcomes, including blood pressure, heart rate variability, and muscle fatigue, are monitored throughout the intervention period.
Behavioral: Isometric Exercise Training (IET)
Participants perform four repetitions of 90 degree bilateral isometric leg extensions on a dynamometer at 30% of their maximum voluntary contraction (MVC). Each contraction is held for 2 minutes, with 2-minute rest intervals between bouts. Sessions are performed three times per week for four weeks. This behavioral intervention is designed to investigate the acute and chronic effects of isometric exercise on blood pressure, heart rate variability, and muscle fatigue.
Other Names:
  • Static Strength Training
  • Leg Extension Hold Training
Experimental: Expectation-Enhancing Info + Isometric Exercise
Participants in this group complete repeated isometric exercise training sessions. Prior to training, they receive an expectation-enhancing informational presentation that emphasizes the effectiveness of isometric exercise as a non-pharmacological intervention for reducing blood pressure. The exercise consists of bilateral isometric leg extensions on a dynamometer. Blood pressure, heart rate variability, and muscle activity are assessed to determine physiological responses to the intervention.
Behavioral: Isometric Exercise Training (IET)
Participants perform four repetitions of 90 degree bilateral isometric leg extensions on a dynamometer at 30% of their maximum voluntary contraction (MVC). Each contraction is held for 2 minutes, with 2-minute rest intervals between bouts. Sessions are performed three times per week for four weeks. This behavioral intervention is designed to investigate the acute and chronic effects of isometric exercise on blood pressure, heart rate variability, and muscle fatigue.
Other Names:
  • Static Strength Training
  • Leg Extension Hold Training
Behavioral: Expectation-Enhancing Informational Framing
Participants receive a brief standardized presentation highlighting isometric exercise as an evidence-based intervention for lowering blood pressure. The presentation includes statements designed to enhance outcome expectations based on prior literature and expert framing.
No Intervention: No-Intervention Control
Participants in this group do not receive any intervention or educational presentation. They attend study visits for assessment purposes only. Measurements include resting blood pressure, heart rate variability, and muscle activity, allowing for comparison with the intervention groups to evaluate the effects of isometric exercise training.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Resting Systolic Blood Pressure
Time Frame: Baseline to Post-Intervention (approximately 4 weeks)
Systolic blood pressure will be measured at rest using a Task Force Monitor prior to and after the isometric exercise intervention period. The primary outcome is the change in resting systolic blood pressure from baseline to final testing. Measurements are taken in a seated position following standard resting protocols.
Baseline to Post-Intervention (approximately 4 weeks)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in Diastolic Blood Pressure
Time Frame: Baseline to Post-Intervention (approximately 4 weeks)
Diastolic blood pressure will be assessed in the same manner as systolic. The secondary outcome is the change in diastolic values from baseline to final testing.
Baseline to Post-Intervention (approximately 4 weeks)
Post-Exercise Hypotension Response
Time Frame: During the first week of the exercise intervention. Sessions 1, 2 and 3.
Post-exercise hypotension will be evaluated as the change in systolic and diastolic blood pressure immediately following each isometric exercise session, compared to pre-exercise baseline.
During the first week of the exercise intervention. Sessions 1, 2 and 3.
Change in Heart Rate Variability (HRV)
Time Frame: Baseline to Post-Intervention (approximately 4 weeks)
HRV will be analyzed using Task Force Monitor data to assess autonomic modulation. Measures include time-domain (e.g., RMSSD) and frequency-domain (e.g., LF/HF ratio) indices.
Baseline to Post-Intervention (approximately 4 weeks)
Change in Muscle Fatigue Markers (EMG)
Time Frame: Baseline to Post-Intervention (Approximately 4 weeks)
Muscle fatigue will be assessed using surface electromyography (EMG) of the vastus lateralis. Fatigue indices include changes in median frequency and torque stability over repeated contractions.
Baseline to Post-Intervention (Approximately 4 weeks)

Collaborators and Investigators

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

Sponsor

Canterbury Christ Church University

Investigators

  • Principal Investigator: Sean Machak, Canterbury Christ Church 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 (Actual)

April 21, 2025

Primary Completion (Estimated)

August 30, 2025

Study Completion (Estimated)

September 1, 2025

Study Registration Dates

First Submitted

April 7, 2025

First Submitted That Met QC Criteria

April 17, 2025

First Posted (Actual)

April 22, 2025

Study Record Updates

Last Update Posted (Actual)

May 16, 2025

Last Update Submitted That Met QC Criteria

May 15, 2025

Last Verified

April 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • ETH2223-0326

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

This is an early-phase investigator-led study involving a small sample size. At this stage, there are no plans to share individual participant data due to ethical and data governance constraints outlined in the approved protocol. Aggregated results may be shared through publication or presentation.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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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