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

Canterbury Christ Church University

Status: Enrolling

Conditions: Hypertension; Elevated Blood Pressure; Sedentary Lifestlye

Treatments: Behavioral: Expectation-Enhancing Informational Framing; Behavioral: Isometric Exercise Training (IET)

Study type: Interventional

Funder types: Other

Identifiers

NCT06937164

ETH2223-0326

Details and patient eligibility

About

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.

Enrollment: 36 estimated patients

Sex: All

Ages: 18 to 55 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Single Blind

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36 participants in 3 patient groups

Neutral Information + Isometric Exercise

Experimental group

Description:

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.

Treatment:

Behavioral: Isometric Exercise Training (IET)

Expectation-Enhancing Info + Isometric Exercise

Experimental group

Description:

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.

Treatment:

Behavioral: Isometric Exercise Training (IET)

Behavioral: Expectation-Enhancing Informational Framing

No-Intervention Control

No Intervention group

Description:

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.