Effect of Training Intensity on Microvascular Function

NCT07237854 | Completed

• 1 other identifier: ULB
• Study Type: interventional
• Target: 25
• Locations: 1 country
• Sites: 1

Brief Summary

The aim of this trial is to investigate the effect of aerobic training intensity on muscle vascular function: continuous versus interval.

Conditions

Vascular Remodeling; Sedentary Behavior; Hemodynamic Rebound

Keywords

Microcirculation; Hemodynamic Instability; Microvascular Density; Quadriceps Muscle; Endurance Training; High-Intensity Interval Training

Outcome Measures

Primary Outcomes (1)

• Percutaneous muscle biopsies of the vastus lateralis

  Muscle tissue samples obtained from the vastus lateralis were processed using optical clearing and immunohistochemical staining techniques to visualize the microvascular network. Confocal microscopy was employed to acquire high-resolution three-dimensional images of arterioles, capillaries, and venules. Quantitative assessments included: 1. Internal diameter measurements, based on endothelial cell boundaries (intima layer) 2. External diameter measurements, based on smooth muscle cells and pericytes (media layer) 3. Capillary density, determined by counting the number of capillaries per sample volume

  At baseline and after completion of the 8-week intervention

Secondary Outcomes (2)

• Cardiopulmonary Exercise Testing (CPET)

  At baseline and after completion of the 8-week intervention

• Maximal Cardiac Output Measurement Using Inert Gas Rebreathing (Innocor)

  At baseline and after completion of the 8-week intervention

Study Arms (2)

Moderate-Intensity Continuous Training (MICT): 34 min at 65% maximal heart rate

EXPERIMENTAL

Participants performed a 3-minute warm-up at 50% of their maximal heart rate (HRmax), as determined during baseline cardiopulmonary exercise testing (ergospirometry), followed by 40 minutes of continuous cycling at 65% of their VO₂max. Sessions were conducted three times per week for a total duration of 8 weeks.

Procedure: Percutaneous muscle biopsies of the vastus lateralis (quadriceps); Other: Measurement of the maximal oxygen uptake (VO2max); Other: Non-Invasive Cardiac Output Measurement (Innocor)

High-Intensity Interval Training (HIIT): 2x2 min at 65% and 90% of maximal heart rate

EXPERIMENTAL

Participants performed a 3-minute warm-up at 50% of their maximal heart rate (HRmax), as determined during baseline cardiopulmonary exercise testing (ergospirometry). The main training protocol consisted of alternating 2-minute cycling bouts: 2 minutes at 65% HRmax followed by 2 minutes at 90% HRmax, repeated continuously for a total of 28 minutes. Sessions were conducted three times per week over an 8-week period.

Procedure: Percutaneous muscle biopsies of the vastus lateralis (quadriceps); Other: Measurement of the maximal oxygen uptake (VO2max); Other: Non-Invasive Cardiac Output Measurement (Innocor)

Interventions

Percutaneous muscle biopsies of the vastus lateralis (quadriceps) PROCEDURE

Percutaneous muscle biopsies of the vastus lateralis (quadriceps) were performed under local anesthesia. Samples were collected at baseline and/or post-intervention to assess microvascular structure, fiber composition, and molecular adaptations to aerobic training.

High-Intensity Interval Training (HIIT): 2x2 min at 65% and 90% of maximal heart rate; Moderate-Intensity Continuous Training (MICT): 34 min at 65% maximal heart rate

Measurement of the maximal oxygen uptake (VO2max) OTHER

Cardiopulmonary Exercise Testing (CPET) Maximal oxygen consumption (VO₂max) was assessed using an incremental stepwise protocol on a cycle ergometer. Participants performed the test at baseline and after the 8-week training intervention. Respiratory gas exchange was continuously measured using a COSMED K5 portable metabolic system, which provided breath-by-breath analysis of oxygen uptake (VO₂), carbon dioxide production (VCO₂), and ventilation parameters. The test was terminated upon volitional exhaustion or when predefined criteria for VO₂max plateau were met.

High-Intensity Interval Training (HIIT): 2x2 min at 65% and 90% of maximal heart rate; Moderate-Intensity Continuous Training (MICT): 34 min at 65% maximal heart rate

Non-Invasive Cardiac Output Measurement (Innocor) OTHER

Maximal cardiac output was assessed at peak exercise intensity during cardiopulmonary exercise testing (CPET) using the Innocor device. This system employs the inert gas rebreathing technique, which involves the controlled inhalation of a gas mixture containing nitrous oxide (N₂O) and sulfur hexafluoride (SF₆). By analyzing the washout kinetics of these gases during rebreathing, the device estimates pulmonary blood flow, which is then used to calculate cardiac output non-invasively. Measurements were performed at the maximal workload reached during the incremental cycling test.

High-Intensity Interval Training (HIIT): 2x2 min at 65% and 90% of maximal heart rate; Moderate-Intensity Continuous Training (MICT): 34 min at 65% maximal heart rate

Eligibility Criteria

• Age: 18 Years - 45 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy female or male between 18 and 45 years
• Be sedentary
• Able to cycle
• Able to provide written informed consent

You may not qualify if:

• Have a pathology that may impact vascular function as :
• cardiac pathology
• pneumological pathology
• metabolic pathology
• Smoke

Sponsors & Collaborators

• Université Libre de Bruxelles: lead

Study Sites (1)

Université Libre de Bruxelles, Faculté des Sciences de la motricité, Laboratoire de kinésithérapie

Brussels, Anderlecht, 1070, Belgium

Location

MeSH Terms

Conditions

Vascular Remodeling; Sedentary Behavior

Condition Hierarchy (Ancestors)

Pathological Conditions, Anatomical; Pathological Conditions, Signs and Symptoms; Pathologic Processes; Behavior

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Masking Details: Participants and the researcher will know the group allocation and therfore cannot be blinded.
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Research Scientist, Reasearch Unit in Rehabilitation Sciences

Model Details: A parallel group randomised controlled trial will be used to determine the superiority of high-intensity interval training versus continuous training on the improvement of quadricpes microvascular function.

Study Record Dates

• First Submitted: September 26, 2022
• First Posted: November 20, 2025
• Study Start: January 22, 2022
• Primary Completion: August 15, 2024
• Study Completion: December 31, 2024
• Last Updated: November 20, 2025

Record last verified: 2025-10

Data Sharing

• IPD Sharing: Will not share

Locations

BE (1)