Oxygen as a Metabolic Modulator: Divergent Physiological Adaptations to Hypoxic and Hyperoxic Tabata Training.

April 25, 2026 updated by: Costantino Balestra, Haute Ecole Bruxelles-Brabant

The purpose of this study is to examine how breathing air with different oxygen concentrations (higher or lower than normal) during high-intensity interval training affects:

  • Aerobic capacity (VO₂max)
  • Ventilatory thresholds
  • Blood lactate levels
  • Perceived exertion This research aims to better understand how oxygen availability influences physiological adaptations to exercise.

If you agree to participate, you will undergo the following:

Baseline testing:

  • Cardiopulmonary exercise test (cycling until exhaustion)
  • Measurement of oxygen consumption, heart rate, and ventilatory thresholds
  • Blood lactate measurement (finger prick)

Training intervention (3 weeks):

  • 3 sessions per week (total of 9 sessions)
  • High-intensity interval training (Tabata protocol: 8 × 20 seconds effort / 10 seconds rest)
  • Exercise performed on an air-resistance cycle ergometer

During training, you will breathe either:

  • Hyperoxic air (high oxygen concentration) or
  • Hypoxic air (low oxygen concentration) You will be randomly assigned to one of these conditions.

Post-intervention testing:

• Same assessments as baseline

The risks associated with this study are similar to those encountered during high-intensity exercise:

  • Fatigue
  • Muscle soreness
  • Shortness of breath
  • Temporary discomfort from finger-prick blood sampling

Breathing altered oxygen concentrations (hypoxia or hyperoxia) may induce:

  • Mild dizziness
  • Increased breathing effort (hypoxia)
  • Sensations of ease or altered effort perception (hyperoxia) All sessions are supervised by trained personnel, and safety monitoring is ensured throughout the study

You may benefit from:

  • Improved physical fitness
  • Detailed physiological assessment (VO₂max, thresholds) However, no direct health benefit is guaranteed. Your participation is entirely voluntary.
  • You may withdraw at any time
  • You do not need to provide a reason
  • Withdrawal will not affect your academic or professional standing

All collected data will be:

  • Anonymized
  • Stored securely
  • Used only for research purposes Your identity will not be disclosed in any publication. Data will be handled in accordance with applicable data protection regulations (GDPR).

You have the right to:

  • Access your data
  • Request correction or deletion where applicable

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

23

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Belgium
    • Brussels Capital
      • Brussels, Brussels Capital, Belgium, 1040
        • Haute Ecole Bruxelles Brabant - HE2B

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • recreationally active
  • male
  • 18-35 years old

Exclusion Criteria:

  • engaged in professional or elite-level sports training
  • cardiovascular, pulmonary, metabolic, or neurological disease
  • taking medications known to influence cardiovascular or metabolic responses to exercise To minimize potential confounding factors, participants were instructed to refrain from strenuous physical activity, alcohol consumption, caffeine intake, and smoking for at least 24 hours before each testing session, in accordance with standard exercise testing procedures recommended in exercise physiology guidelines

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Hyperoxia group
inspired oxygen fraction (FiO₂) = 0.60 during Tabatha protocol
Other: FIO2 modulation during HIIT protocol on assault bike
Normobaric hyperoxic breathing during high-intensity interval training (FiO2 0.60) and hypoxic (FiO2 0.16)
Experimental: Hypoxia group
inspired oxygen fraction (FiO₂) = 0.16 during Tabatha protocol
Other: FIO2 modulation during HIIT protocol on assault bike
Normobaric hyperoxic breathing during high-intensity interval training (FiO2 0.60) and hypoxic (FiO2 0.16)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
maximal oxygen uptake (VO₂max)
Time Frame: From enrollment to the end of protocol at 3 weeks
VO2max represents the maximal rate at which an individual can consume oxygen during incremental exercise. It is measured during a graded exercise test (e.g., treadmill or cycle ergometer) using indirect calorimetry. It reflects aerobic capacity and cardiovascular fitness. Higher values indicate better aerobic performance and endurance capacity.
From enrollment to the end of protocol at 3 weeks

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
the first and second ventilatory thresholds (VT1, VT2)
Time Frame: from enrollment to the end of the protocol at 3 weeks
VT1 (first ventilatory threshold) corresponds to the exercise intensity at which ventilation begins to increase disproportionately relative to oxygen uptake, indicating the onset of lactate accumulation. VT2 (second ventilatory threshold) marks a further disproportionate increase in ventilation due to metabolic acidosis. These thresholds are determined from gas exchange analysis during exercise testing and reflect submaximal aerobic and anaerobic transition points.
from enrollment to the end of the protocol at 3 weeks
peak blood lactate
Time Frame: from enrollment to the end of protocol at 3 weeks
Peak blood lactate is the highest concentration of lactate measured in the blood during or immediately after maximal exercise. It is assessed via capillary or venous blood sampling. This measure reflects the degree of anaerobic metabolism and glycolytic contribution during high-intensity effort.
from enrollment to the end of protocol at 3 weeks
session rating of perceived exertion (RPE).
Time Frame: from enrollment to the end of the protocol at 3 weeks
RPE is a subjective measure of exercise intensity based on an individual's perception of effort, typically assessed using standardized scales such as the Borg scale (6-20 or 0-10). It integrates physiological and psychological responses to exercise and is useful for monitoring training load and tolerance.
from enrollment to the end of the protocol at 3 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Haute Ecole Bruxelles-Brabant

Investigators

  • Study Director: Clément Levêque, PhD, HE2B

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 10, 2023

Primary Completion (Actual)

June 10, 2023

Study Completion (Actual)

December 15, 2025

Study Registration Dates

First Submitted

April 5, 2026

First Submitted That Met QC Criteria

April 22, 2026

First Posted (Actual)

April 27, 2026

Study Record Updates

Last Update Posted (Actual)

April 30, 2026

Last Update Submitted That Met QC Criteria

April 25, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • B200-2020-088

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Data are collected for this study only. The experiments opens new questions and so new data collection

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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