Blood Pressure Following Isometric Exercise in Inactive Adults

NCT06937164 | Recruiting

• 1 other identifier: ETH2223-0326
• Study Type: interventional
• Target: 36
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Hypertension; Elevated Blood Pressure; Sedentary Lifestlye

Keywords

Isometric Exercise; Blood Pressure; Post-Exercise Hypotension; Physical Inactivity; Heart Rate Variability; Electromyography (EMG); Muscle Fatigue; Cardiovascular Adaptation; Exercise Intervention; Non-Pharmacological Treatment; Hypertension Prevention; Autonomic Nervous System; BELIEF-BP

Outcome Measures

Primary Outcomes (1)

• Change in Resting Systolic Blood Pressure

  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 Outcomes (4)

• Change in Diastolic Blood Pressure

  Baseline to Post-Intervention (approximately 4 weeks)

• Post-Exercise Hypotension Response

  During the first week of the exercise intervention. Sessions 1, 2 and 3.

• Change in Heart Rate Variability (HRV)

  Baseline to Post-Intervention (approximately 4 weeks)

• Change in Muscle Fatigue Markers (EMG)

  Baseline to Post-Intervention (Approximately 4 weeks)

Study Arms (3)

Neutral Information + Isometric Exercise

EXPERIMENTAL

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)

Expectation-Enhancing Info + Isometric Exercise

EXPERIMENTAL

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); Behavioral: Expectation-Enhancing Informational Framing

No-Intervention Control

NO INTERVENTION

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.

Interventions

Isometric Exercise Training (IET) BEHAVIORAL

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.

Also known as: Static Strength Training, Leg Extension Hold Training

Expectation-Enhancing Info + Isometric Exercise; Neutral Information + Isometric Exercise

Expectation-Enhancing Informational Framing BEHAVIORAL

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.

Expectation-Enhancing Info + Isometric Exercise

Eligibility Criteria

• Age: 18 Years - 55 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• Canterbury Christ Church University: lead

Study Sites (1)

Canterbury Christ Church University

Canterbury, Kent, CT1 1QU, United Kingdom

RECRUITING

MeSH Terms

Conditions

Hypertension; Post-Exercise Hypotension; Sedentary Behavior

Condition Hierarchy (Ancestors)

Vascular Diseases; Cardiovascular Diseases; Orthostatic Intolerance; Primary Dysautonomias; Autonomic Nervous System Diseases; Nervous System Diseases; Hypotension; Behavior

Study Officials

• Sean Machak

  Canterbury Christ Church University

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Sean Machak

CONTACT

+447864658805; s.machak2125@canterbury.ac.uk

Philip Hurst

CONTACT

+44 (0)1227 927700; philip.hurst@canterbury.ac.uk

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Masking Details: Participants are blinded to group assignment. They are not informed whether they are receiving neutral or expectation-enhancing information, or whether they are in a control group. Due to the nature of the study, the researcher is not blinded.
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Participants are randomly assigned to one of three parallel groups: (1) isometric exercise training (IET) with neutral information, (2) IET with expectation-enhancing information, or (3) a no-intervention control group. Intervention groups complete repeated isometric leg extension sessions across multiple visits. Prior to training, participants receive distinct information to influence their beliefs about IET. The control group does not receive training or information. Participants are blinded to group assignment, and outcomes such as blood pressure, heart rate variability, and muscle fatigue are assessed independently across groups.

Study Record Dates

• First Submitted: April 7, 2025
• First Posted: April 22, 2025
• Study Start: April 21, 2025
• Primary Completion: August 30, 2025
• Study Completion: September 1, 2025
• Last Updated: May 16, 2025

Record last verified: 2025-04

Data Sharing

• IPD Sharing: Will not share

Locations

GB (1)