Acute Autonomic Responses During and After BFR Training
Trial statusNot yet recruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age18+
SponsorEgas Moniz - Cooperativa de Ensino Superior, CRL
About this trial
The goal of this clinical trial is to compare how the body's nervous system responds to two different types of leg exercise in young and older adults. One type is low-intensity exercise with blood flow restriction (BFR) , where a cuff partially reduces blood flow to the legs during exercise. The other type is traditional high-intensity resistance training (HIRT), which uses heavier weights.
The main questions it aims to answer are:
Does low-intensity exercise with BFR cause less stress on the nervous system during exercise compared to high-intensity training? Does low-intensity exercise with BFR lead to faster recovery of the nervous system after exercise compared to high-intensity training? Do these responses differ between young adults and older adults? Researchers will compare low-intensity exercise with BFR to high-intensity training to see which approach is gentler on the nervous system during and after exercise.
Participants will:
Attend three visits to the research lab Complete a strength test on leg exercise machines Perform two separate exercise sessions: one with low-intensity exercise and BFR, and one with high-intensity training Have their heart rate, blood pressure, and heart rate variability monitored continuously during and after each exercise session
Eligibility criteria
This trial accepts healthy volunteersQualifiers
Young adults aged 18-24 years
Older adults aged 60 years and above
Willing and able to provide written informed consent
Able to comply with study procedures and visit schedule
Disqualifiers
Medications affecting cardiac activity (e.g., beta-blockers, calcium channel blockers, antiarrhythmics)
Tobacco use
Sleep apnea
Body mass index (BMI) greater than 30 kg/m²
Trial design
Design model
Crossover
Treatments tested in this trial
High-Intensity Resistance Training (HIRT)
Other interventionParticipants perform bilateral knee extensions and leg curls at 75% of their one-repetition maximum (1RM). The protocol consists of 3 sets of 10 repetitions with 2-minute rest intervals between sets. Total exercise duration is approximately 30 minutes.
Low-Intensity Resistance Training with Blood Flow Restriction (LIRT-BFR)
Other interventionParticipants perform bilateral knee extensions and leg curls at 30% of their one-repetition maximum (1RM) while a pneumatic cuff is applied to the most proximal portion of both thighs. The cuff is inflated to 1.3 times the individual's ankle systolic blood pressure. The protocol consists of 4 sets of 20 repetitions with 30-second rest intervals between sets. Total exercise duration is approximately 30 minutes. Cuff pressure is maintained continuously throughout sets and rest periods and is released immediately after the final repetition.
Treatment groups
48 Participants
are divided into 3 treatment groupsGroup A: Low-Intensity + Blood Flow RestrictionExperimental treatment 1 intervention
Group B: High-Intensity Resistance Training (HIRT)Active comparator 1 intervention
Group C: No exercise or blood flow restrictionNo intervention 0 interventions
Trial outcomes
Primary outcomes
1
Changes in Time-Domain Heart Rate Variability Indices
Mean change from baseline in time-domain heart rate variability indices: RMSSD (root mean square of successive differences, reflecting vagal modulation), SDNN (standard deviation of normal-to-normal intervals, reflecting overall autonomic modulation), and pNN50 (percentage of successive R-R intervals \>50 ms). These indices will be derived from continuous R-R interval recordings (Finapres Nova) during supine rest. Higher values indicate better parasympathetic modulation and autonomic flexibility.
Time frame
Baseline (15-minute seated rest); during exercise (continuous throughout the 30-minute exercise bout); and 30 minutes into recovery (seated position)Secondary outcomes
1
Changes in Frequency-Domain Heart Rate Variability Indices
Mean change from baseline in frequency-domain heart rate variability indices: low-frequency power (LF, ms²), high-frequency power (HF, ms²), and LF/HF ratio. Spectral analysis will be performed using a Daubechies-12 discrete wavelet transform on continuous R-R interval recordings (Finapres Nova) during supine rest. Higher HF indicates better parasympathetic modulation; lower LF/HF ratio indicates better sympathovagal balance.
Time frame
Baseline (15-minute seated rest); during exercise (continuous throughout the 30-minute exercise bout); and 30 minutes into recovery (seated position)2
Changes in Non-Linear Heart Rate Variability Indices
Mean change from baseline in non-linear heart rate variability indices derived from Poincaré plot analysis: SD1 (reflecting short-term variability, predominantly parasympathetic modulation), SD2 (reflecting long-term variability, overall autonomic modulation), and SD1/SD2 ratio. Derived from continuous R-R interval recordings (Finapres Nova) during supine rest.
Time frame
Baseline (15-minute seated rest); during exercise (continuous throughout the 30-minute exercise bout); and 30 minutes into recovery (seated position)3
Changes in Cardiovagal Baroreflex Sensitivity (BRS)
Mean change from baseline in baroreflex sensitivity (BRS) estimated using the spontaneous sequence method, which identifies concordant systolic blood pressure and R-R interval ramps. BRS gain is expressed as ms/mmHg. Higher BRS gain indicates better reflex integrity and better blood pressure stability.
Time frame
Baseline (15-minute seated rest); during exercise (continuous throughout the 30-minute exercise bout); and 30 minutes into recovery (seated position)4
Changes in Blood Pressure
Mean change from baseline in beat-to-beat systolic blood pressure (SBP) and diastolic blood pressure (DBP). Both measures will be derived from finger plethysmography (Finapres Nova) during supine rest, validated against brachial readings (SunTech Tango+). Units: mmHg. For SBP, higher values indicate higher cardiovascular load. For DBP, higher values indicate higher cardiovascular load.
Time frame
Baseline (15-minute seated rest); during exercise (continuous throughout the 30-minute exercise bout); and 30 minutes into recovery (seated position)Sponsors and contacts
Click on the lead sponsor to view all of their trials.
Source ClinicalTrials.gov
This trial is not recruiting at the moment. You can still explore other options: