An interventional study of Moderate hypoxia and Normoxia in Normoxia, Intermittent Moderate Hypoxia and Continuous Moderate Hypoxia, sponsored by Universite du Littoral Cote d'Opale. Recruiting at 1 site in France. Open to participants aged 18 Years to 65 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-21.
Sponsored by Universite du Littoral Cote d'Opale · Not applicable, Interventional, and Basic science
Hypoxia, defined as a reduction in the availability of oxygen, induces significant physiological adaptations. While the deleterious effects of severe and chronic hypoxia are well documented, several studies indicate that moderate hypoxia - particularly when administered intermittently - may produce beneficial effects on cardiometabolic health (e.g., improved regulation of blood pressure and better glycaemic control). However, its impact on the dynamics of brain circuits in humans remains relatively underexplored. The present project aims to characterise the effects of continuous and intermittent moderate hypoxia on resting-state brain dynamics in healthy adults. To this end, simultaneous electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) recordings will be conducted in order to extract functional and haemodynamic markers of brain activity. This project will contribute to a better understanding of the neurophysiological mechanisms associated with hypoxic conditioning and to the assessment of its potential application in innovative therapeutic approaches.
Hypoxia refers to a condition in which the availability of oxygen (O₂) is reduced relative to normal conditions. While severe hypoxia is well known for its deleterious effects, moderate hypoxia - particularly when administered intermittently - may produce potentially beneficial effects on cardiometabolic health, such as improved regulation of blood pressure and enhanced energy metabolism.
Animal models indicate that hypoxia can promote the expression of neurotrophic factors, stimulate neuroplasticity, and enhance cerebrovascular function. In humans, several studies suggest that intermittent hypoxia induces more pronounced cardiometabolic adaptations than continuous hypoxia and may improve certain cognitive functions in older adults. Recent findings also indicate that moderate hypoxia alters spontaneous brain activity at rest, particularly in the alpha frequency band, suggesting a possible influence on functional brain networks.
However, the effects of moderate hypoxia on resting-state brain dynamics remain poorly documented in humans. A detailed characterisation of both the electrical and haemodynamic responses of the brain is therefore required in order to better understand the potential adaptive processes involved and to evaluate the relevance of intermittent hypoxia as a non-pharmacological intervention for optimising brain health.
The primary objective of this project is to evaluate the effects of continuous and intermittent moderate hypoxia on resting-state brain dynamics in healthy individuals. To this end, simultaneous EEG and fNIRS recordings will be collected in order to extract functional markers of resting brain activity. A secondary objective is to investigate the impact of moderate hypoxia on brain connectivity and corticospinal excitability.
This is a single-centre exploratory descriptive study. Each participant will be assessed during three experimental sessions (i.e. intermittent hypoxia, continuous hypoxia, and normoxia) separated by at least one week and presented in a pseudo-randomised order. During the hypoxic periods, a peripheral oxygen saturation (SpO₂) between 85% and 90% will be targeted.
Participants will be fitted with a cap enabling the simultaneous recording of EEG activity and haemodynamic signals (via measurements of oxyhaemoglobin [HbO₂] and deoxyhaemoglobin [HbR] concentrations) using fNIRS. The activity of the first dorsal interosseous muscle of the dominant hand will be recorded using surface electromyography. During the recordings (i.e., hypoxia or normoxia exposure), participants will remain at rest, without any motor activity or specific cognitive stimulation.
Corticospinal excitability will be assessed using TMS before and after each hypoxic exposure period. For this purpose, we will measure the amplitude of motor-evoked potentials in the first dorsal interosseous muscle of the dominant hand following stimulation of the contralateral motor cortex using TMS at 120% of the resting motor threshold. This measure will be complemented by the assessment of the efficiency of three intracortical mechanisms that contribute to changes in the excitability of the primary motor cortex: short- and long-interval intracortical inhibition (SICI and LICI, respectively), as well as intracortical facilitation (ICF). These measures will be obtained using paired-pulse TMS protocols.
1,076 studies on the registry are indexed under Hypoxia; 213 are open to participants now.
This study's planned enrollment of 36 is below the median of 45 across 769 interventional studies indexed under Hypoxia.
Browse Hypoxia studies →Universite du Littoral Cote d'Opale is the lead sponsor of 10 studies on the registry; 5 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The sham condition will consist of 30 minutes of continuous exposure to ambient air, inhaled through the same mask as that used during the hypoxia conditions.
Device: Normoxia · Device: Transcranial Magnetic Stimulation
The duration of exposure to continuous hypoxia will be 30 minutes. A peripheral oxygen saturation (SpO₂) between 85% and 90% will be targeted. Hypoxic exposure will take place at rest, with the participant comfortably seated. In addition, the hypoxic device used in the study is equipped with a safety system allowing a minimum fraction of inspired oxygen (FiO₂) to be defined. This threshold will be set at 10%, ensuring that the FiO₂ cannot fall below this value.
Device: Moderate hypoxia · Device: Transcranial Magnetic Stimulation
The intermittent hypoxia condition will consist of six periods of 5 minutes of hypoxia interspersed with 5-minute periods of normoxia. During the hypoxic periods, a SpO₂ between 85% and 90% will be targeted. As in the continuous condition, hypoxic exposure will take place at rest, with the participant comfortably seated. The hypoxic device also includes a safety system allowing a minimum FiO₂ to be defined; this threshold will be set at 10%, ensuring that the FiO₂ cannot fall below this value.
Device: Moderate hypoxia · Device: Transcranial Magnetic Stimulation
Altitude conditions (normobaric hypoxia) will be reproduced using the OnePlus VA device (GO2Altitude, Biomedtech, Melbourne, Australia). This device modulates the fraction of inspired oxygen (FiO₂) through a patented semi-permeable membrane system developed by the company. It thereby produces a gas mixture that is inhaled by the participant through a mask. This device included an oxygen-reduction algorithm, that adjusts the FiO₂ in real time according to a target peripheral oxygen saturation (SpO₂ = 85-90%).
Ambient air will be delivered through the same mask as that used during the hypoxia conditions.
Single- and paired-pulse TMS will be applied over the primary motor cortex (M1) to assess corticospinal excitability, along with intracortical inhibitory and facilitatory mechanisms. Motor-evoked potentials will be recorded from the abductor pollicis brevis (APB) muscle of the dominant hand.
Also known as: TMS
Electrical brain activity
Electroencephalography (EEG) data will be recorded using a SAGA system (TMSi, Einsteinweg, The Netherlands). This system includes 64 Ag/AgCl pin-type electrodes. An additional electrode will be positioned on either the left or right mastoid. The primary outcome will be the variation in spectral power within the alpha frequency band.
Time frame: Assessed throughout the intervention, at Day 2, 3, and 4 of the protocol.
Haemodynamic activity
A Brite system (Artinis, Einsteinweg, The Netherlands) will be used to collect functional near-infrared spectroscopy (fNIRS) data. The equipment comprises four LED emitters and four photodiode receivers. A nine-channel montage will be designed to cover the regions of interest, namely the dorsolateral prefrontal cortex, the ventromedial prefrontal cortex, and the anterior prefrontal cortex. The primary outcome will be the variation in deoxyhaemoglobin (HbR).
Time frame: Assessed throughout the intervention, at Day 2, 3, and 4 of the protocol.
Corticospinal excitability
Corticospinal excitability will be assessed using transcranial magnetic stimulation (TMS) applied to the primary motor cortex. Motor evoked potentials (MEPs) are recorded using surface electromyography from the abductor pollicis brevis (APB) muscle of the dominant hand.The primary outcome will be the slope of the I/O curve.
Time frame: Assessed at baseline and immediately post-intervention during each of the three experimental sessions (i.e., intermittent moderate hypoxia, continuous moderate hypoxia, normoxia).
EEG brain connectivity
Resting-state cortical connectivity will be examined using the EEG data, on which coherence analyses will be applied. The outcome measure will be the degree of functional connectivity between cortical regions, quantified through coherence values across specific frequency bands (e.g., alpha, beta), reflecting the synchronisation of neural activity between these regions.
Time frame: Assessed throughout the intervention, at Day 2, 3, and 4 of the protocol.
fNIRS brain connectivity
Resting-state cortical connectivity will be examined using the fNIRS signals, through correlations of deoxyhaemoglobin (HbR) between the cortical regions of interest. The outcome measure will be the strength of functional connectivity between these regions, quantified by the correlation coefficients of haemodynamic fluctuations, reflecting the synchrony of cortical activity at rest.
Time frame: Assessed throughout the intervention, at Day 2, 3, and 4 of the protocol.
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Universite du Littoral Cote d'Opale