Neural Contributions to Exercise-Induced Hypoalgesia With Blood Flow Restriction

NCT ID: NCT07122011

Last Updated: 2025-08-19

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: NA
• Total Enrollment: 20 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-08-04
• Study Completion Date: 2025-10-31

Brief Summary

This experimental study explores the neurophysiological mechanisms associated with pain modulation following a single session of low-intensity resistance exercise combined with BFR in healthy young adults. The study evaluates changes in sensory thresholds before and after the intervention using validated quantitative sensory testing (QST) methods. These include pressure pain thresholds, conditioned pain modulation, thermal thresholds, and temporal summation. The findings may contribute to a better understanding of the role of the nervous system in exercise-induced hypoalgesia, particularly in response to BFR protocols, with implications for future research in pain and rehabilitation.

Detailed Description

Exercise-induced hypoalgesia (EIH) is a physiological response characterized by reduced pain sensitivity following physical activity. Several central and peripheral mechanisms have been proposed to explain EIH, including activation of descending inhibitory pathways and peripheral nociceptor modulation. BFR training involves the application of controlled vascular occlusion during low-load exercise and has shown promising results in enhancing both muscle function and pain modulation.

This is a single-arm, pre-post experimental study involving healthy adults aged 18-35 years. All participants undergo a single session of low-intensity resistance exercise involving the lower limbs, performed under 60% limb occlusion pressure. QST is performed before and immediately after the intervention, including:

Pressure Pain Thresholds (PPT) measured with a digital algometer

Conditioned Pain Modulation (CPM) using cold-water immersion

Thermal thresholds assessed with a computer-controlled thermode

Temporal summation (TS) of pain via repeated pressure stimuli

The aim of this study is to explore the involvement of neurophysiological mechanisms-both central and peripheral-in the pain modulatory response following BFR exercise. This study is conducted at CUADI (Centro Universitario de Asistencia, Docencia e Investigación) in Rosario, Argentina. The results will contribute to basic science knowledge on pain physiology in healthy individuals and may inform future applied research in rehabilitation contexts.

Sample size considerations:

The estimated sample size is approximately 20 participants. This number is based on a preliminary power analysis conducted from pilot data on PPT changes following cold water immersion, which showed a mean difference of 0.77 kgf with a standard deviation of 0.33 kgf. Using G*Power software (v3.1), the calculated sample size for a paired comparison with 95% power and alpha of 0.05 was 16 subjects. To account for potential data loss or dropouts, we plan to include at least 20 individuals. This sample size is considered adequate for a mechanistic, single-arm pre-post design focusing on within-subject changes in pain modulation outcomes.

Conditions

Healthy

Study Design

• Allocation Method: NA
• Intervention Model: SINGLE_GROUP
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: NONE

Study Groups

Single Group - Low-Intensity Resistance Training with BFR

A single session of low-intensity resistance training combined with BFR applied to the proximal thigh of the dominant leg at 60% of total arterial occlusion pressure. Sensory and pain modulation assessments (PPT, CPM, TS, and thermal thresholds) performed immediately before and after the training session.

Group Type: EXPERIMENTAL

Low-Intensity Resistance Training with BFR

Intervention Type: OTHER

Warm-up: Five minutes of light-intensity cycling on a stationary bike.

Exercises:

1. Bilateral half squat (0°-90°)

2. Single-leg step-down from a 20 cm step

3. Knee extension (90°-0°) at 30% of one-repetition maximum (1RM)

4. Single-leg shallow squat (0°-45°)

Protocol: One set of 30 repetitions (or until volitional fatigue) followed by three sets of 15 repetitions for each exercise.

Rest periods: One minute between sets and two minutes between exercises.

BFR Application: Pneumatic cuff (The Occlusion Cuff Pro®) placed proximally on the dominant thigh, inflated to 60% of complete arterial occlusion (determined via Doppler ultrasound). The cuff remains inflated during sets and rest periods, and is deflated after completion of each exercise.

Interventions

Low-Intensity Resistance Training with BFR

Warm-up: Five minutes of light-intensity cycling on a stationary bike.

Exercises:

1. Bilateral half squat (0°-90°)

2. Single-leg step-down from a 20 cm step

3. Knee extension (90°-0°) at 30% of one-repetition maximum (1RM)

4. Single-leg shallow squat (0°-45°)

Protocol: One set of 30 repetitions (or until volitional fatigue) followed by three sets of 15 repetitions for each exercise.

Rest periods: One minute between sets and two minutes between exercises.

BFR Application: Pneumatic cuff (The Occlusion Cuff Pro®) placed proximally on the dominant thigh, inflated to 60% of complete arterial occlusion (determined via Doppler ultrasound). The cuff remains inflated during sets and rest periods, and is deflated after completion of each exercise.

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• Asymptomatic at the time of evaluation.
• Able to provide written informed consent.
• Available to attend a single evaluation and intervention session at the research center.

Exclusion Criteria

• Bilateral knee symptoms or suspected patellar tendinopathy.
• Increased symptoms with dynamic loading.
• Neurological disorders.
• Inflammatory rheumatic diseases.
• Cardiac diseases.
• Any surgery within the last 3 months.
• Pregnancy.
• Alcohol consumption on the day of participation.
• Hypertension (systolic blood pressure ≥140 mmHg).
• History of deep vein thrombosis.
• History of endothelial dysfunction.
• Peripheral vascular disease.
• Diabetes.
• Active infection.
• Spinal or referred pain.
• Previous experience with blood flow restriction (BFR) training.
• Overweight or obesity.

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 35 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

University of Gran Rosario

OTHER

Sponsor Role: lead

Responsible Party

Leonardo Intelangelo

Director

Responsibility Role: PRINCIPAL_INVESTIGATOR

Locations

University Center for Assistance, Teaching and Research (CUADI)

Rosario, Santa Fe Province, Argentina

Site Status: RECRUITING

Countries

Argentina

Central Contacts

Leonardo Intelangelo, PhD

Role: CONTACT

lintelangelo@ugr.edu.ar

+5493416758135

Facility Contacts

Leonardo Intelangelo, PhD

Role: primary

lintelangelo@ugr.edu.ar

+5493416758135

Other Identifiers

Universidad del Gran Rosario

Identifier Type: -

Identifier Source: org_study_id