An interventional study of Percutaneous muscle biopsies of the vastus lateralis (quadriceps) and Measurement of the maximal oxygen uptake (VO2max) in Vascular Remodeling, Sedentary Behavior and Hemodynamic Rebound, sponsored by Université Libre de Bruxelles. Completed at 1 site in Belgium. Open to participants aged 18 Years to 45 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-11-20.
Sponsored by Université Libre de Bruxelles · Not applicable, Interventional, and Basic science
The aim of this trial is to investigate the effect of aerobic training intensity on muscle vascular function: continuous versus interval.
This trial will compare the hemodynamic effects of aerobic training on muscle microvascular function between participants randomly assigned to one of two groups: a continuous training group and an high-intensity interval training group.
All data concerning the primary and secondary outcomes will be obtained at the start and repeated at the end of 8 weeks aerobic training.
332 studies on the registry are indexed under Sedentary Behavior; 155 are open to participants now.
This study's enrollment of 25 is below the median of 70 across 287 interventional studies indexed under Sedentary Behavior.
Browse Sedentary Behavior studies →Université Libre de Bruxelles is the lead sponsor of 44 studies on the registry; 13 are open to participants now.
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Exclusion Criteria:
Have a pathology that may impact vascular function as :
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)
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)
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.
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.
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.
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
Time frame: At baseline and after completion of the 8-week intervention
Cardiopulmonary Exercise Testing (CPET)
VO₂max was determined using a graded, incremental exercise test performed on a cycle ergometer until volitional exhaustion. Throughout the test, respiratory gases were continuously measured using a metabolic cart (e.g., COSMED K5), which provided breath-by-breath analysis. The following parameters were recorded : 1. VO₂ (oxygen uptake) in mL/min 2. VCO₂ (carbon dioxide production) in mL/min 3. Minute ventilation (VE) in L/min
Time frame: At baseline and after completion of the 8-week intervention
Maximal Cardiac Output Measurement Using Inert Gas Rebreathing (Innocor)
Innocor is a medical device that estimates cardiac output using the inert gas rebreathing technique, a validated non-invasive method. During the procedure, the participant inhales a gas mixture containing nitrous oxide (N₂O) and sulfur hexafluoride (SF₆) through a closed circuit. These inert gases are absorbed and eliminated at rates proportional to pulmonary blood flow. By analyzing the washout kinetics of these gases during a brief rebreathing period, Innocor calculates pulmonary blood flow, which is then used to estimate cardiac output. This measurement is typically performed at rest or at peak exercise intensity, such as during the final stage of a cardiopulmonary exercise test (CPET). The system provides real-time data on: 1. Cardiac output (L/min) 2. Stroke volume (ml/min) 3. Heart rate (bpm) 4. Pulmonary blood flow (L/min)
Time frame: At baseline and after completion of the 8-week intervention
Plan to share: No
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Vascular Remodeling
Université Libre de Bruxelles