Blood Pressure Following Isometric Exercise in Inactive Adults
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18-55
SponsorCanterbury Christ Church University
About this trial
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.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
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
Disqualifiers
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
Trial design
Design model
Parallel
Treatments tested in this trial
Isometric Exercise Training (IET)
BehavioralParticipants 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.
Expectation-Enhancing Informational Framing
BehavioralParticipants 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.
Treatment groups
36 Participants
are divided into 3 treatment groupsGroup A: Neutral Information + Isometric ExerciseExperimental treatment 1 intervention
Group B: Expectation-Enhancing Info + Isometric ExerciseExperimental treatment 2 interventions
Group C: No-Intervention ControlNo intervention 0 interventions
Trial outcomes
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.
Time frame
Baseline to Post-Intervention (approximately 4 weeks)Secondary outcomes
1
Change in Diastolic Blood Pressure
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.
Time frame
Baseline to Post-Intervention (approximately 4 weeks)2
Post-Exercise Hypotension Response
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.
Time frame
During the first week of the exercise intervention. Sessions 1, 2 and 3.3
Change in Heart Rate Variability (HRV)
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.
Time frame
Baseline to Post-Intervention (approximately 4 weeks)4
Change in Muscle Fatigue Markers (EMG)
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.
Time frame
Baseline to Post-Intervention (Approximately 4 weeks)Sponsors and contacts
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Source ClinicalTrials.gov