Elevated Blood Pressure, Hypertension, Sedentary Lifestlye
Conditions
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
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.
Interventions
BEHAVIORALIsometric 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.
BEHAVIORALExpectation-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.
Sponsors
Canterbury Christ Church University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Subject)
Masking description
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.
Intervention model description
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.
Eligibility
Sex/Gender
ALL
Age
18 Years to 55 Years
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Resting Systolic Blood Pressure | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in Diastolic Blood Pressure | 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. |
| Post-Exercise Hypotension Response | 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. |
| Change in Heart Rate Variability (HRV) | 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. |
| Change in Muscle Fatigue Markers (EMG) | 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. |
Countries
United Kingdom
Contacts
Primary ContactSean Machak
Backup ContactPhilip Hurst
Outcome results
None listed