A Comparison Study Between 10 Days of Dry Immersion Versus 10 Days of Head-down Bedrest on 20 Healthy Male Volunteers (VIVALDI 3)

May 5, 2025 updated by: Centre National d'Etudes Spatiales

Standardization of the Dry Immersion Model Used as a Ground-based Model to Mimic Weightlessness. Part 3: a Comparison Study Between 10 Days of Dry Immersion vs. 10 Days of Head-down Bedrest on 20 Healthy Male Volunteers (VIVALDI 3)

The space agencies are actively engaged in studying the physiological adaptation to space environment through studies on board the International Space Station (ISS) but also on the ground. Different methods are used to simulate weightlessness on Earth, including cellular models, animal models using hind-limb unloading, or on humans with unilateral lower limb suspension. However, two approaches, -6° head-down bed rest (HDBR) and dry immersion (DI) have provided possibilities for long-term exposures with findings closest to those seen with a weightless state. They produce changes in body composition (including body fluid redistribution), cardiovascular and skeletal muscle characteristics that resemble the effects of microgravity.

The common physiological denominator is the combination of a cephalad shift of body fluids and reduced physical activity. Being similar in their effects on the human body, these models, however, differ in their specifics and acting factors.

The Head-down Bedrest (HDBR) model has been widely used for this purpose and is considered one of the references for reproducing the physiological effects of weightlessness on Earth. During HDBR, subjects are lying down with an angle of -6° between the feet and head, on their side, their back or their front, but must keep one shoulder in contact with the mattress. All daily activities and tests are performed in this position.

One of the advantages of the HDBR model is that it has now been used in a great number of studies internationally, and its effects have long been described and compared with those of microgravity and spaceflight. Long-term bedrest is the gold-standard method for studying the effects of weightlessness and to test countermeasures.

Dry immersion involves immersing the subject in water covered with an elastic waterproof fabric. As a result, the immersed subject, who is freely suspended in the water mass, remains dry. Within a relatively short duration, the model can faithfully reproduce most physiological effects of actual microgravity, including centralization of body fluids, support unloading, and hypokinesia.

The objective of the present study is to compare the physiological adaptations to10 days of dry immersion versus 10 days of head-down bedrest in 20 healthy male subjects. A set of measurements will assess the changes in the cardiovascular, neuro-ophthalmological, hematological, metabolic, sensorimotor, immune, muscle and bone systems as a result of both models. The most likely outcome of this study will not be to show a clear superiority of one model over the other. Rather, we expect to show differences in kinetics and intensity of adaptations, that should vary from one system to another. This will help future researchers choose the best model depending on the system they are investigating and the rapidity or intensity of the effect they are exploring. The two models, instead of competing with one another, are probably complementary.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
20

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • 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 Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • France
      • Toulouse, France, 31400
        • Medes-Institut de Médecine et de Physiologie Spatiale

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

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

  • Healthy male volunteer (see below the description of medical tests and laboratory analysis performed at the selection visit),
  • Age 20 to 40,
  • No overweight nor excessive thinness with BMI (weight kg/ height m2) between 20 and 26,
  • Height between 165cm and 180 cm,
  • Certified as healthy by a comprehensive clinical assessment (detailed medical history and complete physical examination): in particular, free from any chronic disease or any acute infectious disease or cardiovascular, neurological, ENT (especially orthostatic hypotension and vestibular disorders), orthopaedic or musculoskeletal disorders,
  • Fitness level assessment: 35 ml/min./kg < VO2max < 55 ml/min./kg,
  • Non active smokers,
  • No alcohol, or drug addiction, and no medical treatment,
  • Covered by a Health Insurance System,
  • Having signed the informed consent,
  • Free from any engagement during the study.

Exclusion Criteria:

  • Any history or presence of clinically relevant cardiovascular, neurological or ENT (especially orthostatic hypotension and vestibular disorders), any chronic disease; any acute infectious disease. Particularly:
  • Symptomatic orthostatic hypotension whatever the decrease in blood pressure, or asymptomatic postural hypotension defined by a decrease in SBP equal to or greater than 20 mmHg within 3 minutes when changing from the supine to the standing position,
  • Cardiac rhythm disorders,
  • Hypertension,
  • Chronic back pains,
  • Vertebral fracture, scoliosis or herniated disc,
  • Glaucoma,
  • Self-reported hearing problems,
  • History of migraines,
  • History of hiatus hernia or gastro-esophageal reflux,
  • History of thyroid dysfunction, renal stones, diabetes,
  • History of head trauma,
  • History of genetic muscle and bone diseases of any kind,
  • Past records of thrombophlebitis, family history of thrombosis or positive response in thrombosis screening procedure (anti thrombin III, S-protein, C-protein, factor V Leiden mutation and the mutation 20210 of the prothrombin gene),
  • Signs of venous insufficiency, varicose veins, or telangiectasia
  • Bone mineral density: T-score ≤ -1.5,
  • Poor tolerance to blood sampling,
  • Having given whole blood (more than 7ml/kg) in a period of 8 weeks or less before the start of the experiment, or having given whole blood more than 5 times in the past 12 months,
  • Significant history of allergy, especially no dermatological allergy,
  • History of food allergy,
  • Significant anomaly detected in the biological analysis,
  • Positive reaction to any of the following tests: HVA IgM (hepatitis A), HBs antigen (hepatitis B), anti-HVC antibodies (hepatitis C), anti-HIV1+2 antibodies,
  • Vegetarian or vegan,
  • Refusal to give permission to contact his general practitioner,
  • Subject who, in the judgment of the investigator, is likely to be non-compliant during the study, or unable to cooperate because of a language problem or poor mental development,
  • Subject already participating or in the exclusion period of a clinical research,
  • Subject who has received more than 6000 Euros within 12 months for being a research subject,
  • MRI contraindications:
  • History or active claustrophobia,
  • Osteosynthesis material, presence of metallic implants or any other contra-indication for MRI,
  • Allergy to Gadolinium.
  • Vulnerable persons according to law "Code de la Santé Publique" (L1121-5 to L1121-8) :
  • Persons deprived of their liberty by an administrative or judicial decision,
  • Persons under involuntary psychiatric care,
  • Persons admitted in a health or social establishment for purposes other than research,
  • Minors,
  • Adults subject to legal protection (subject under guardianship or trusteeship) or unable to express their consent.

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

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Dry Immersion arm
10 days of dry immersion
Behavioral: 10 days of dry immersion
The volunteers in this arm will be immersed up to the neck for 10 days in a specially designed bath filled with tap water.
Other Names:
  • Dry Immersion (DI)
Experimental: Bed rest arm
10 days of head down bed rest
Behavioral: 10 days of Head Down Bed Rest
The volunteers in this arm will spend 10 days in -6° head down bed rest.
Other Names:
  • Head Down Tilt (HDT)

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Changes in orthostatic tolerance
Time Frame: At baseline and first day of recovery
Orthostatic tolerance (min) will be assessed during a progressive Lower Body Negative Pressure test (LBNP test)
At baseline and first day of recovery
Changes in peak aerobic power (VO2max test)
Time Frame: At baseline and the first day of recovery
Exercise capacity (ml/kg/min) wil be assessed by graded cycling on sitting ergometer until exhaustion
At baseline and the first day of recovery
Change in plasma volume
Time Frame: At baseline and 3 days after the end of the intervention
Plasma volume (L) will be assessed by the carbon monoxide-rebreathing method
At baseline and 3 days after the end of the intervention
Change in plasma volume percentage
Time Frame: At baseline and at day 1, day 3, day 7 and at the end of the intervention periods
The percentage change in plasma volume versus baseline (%) will be assessed by the Dill and Costill method
At baseline and at day 1, day 3, day 7 and at the end of the intervention periods
Change in fluid shift distribution towards the cardiac and cephalic region
Time Frame: At baseline, the first day to quantify the short term effect, the fifth day and the tenth day of interventions to quantify the long term effect of fluid shift
The consequences of the fluid shift on the cardiac and cephalic area will be assessed by quantifying the carotid and femoral diameters (mm), as well as the carotid intima media thickness (mm) by ultrasound.
At baseline, the first day to quantify the short term effect, the fifth day and the tenth day of interventions to quantify the long term effect of fluid shift
Change in body fluid compartments by bioelectrical impedance analysis
Time Frame: At baseline, during the ten days of intervention and until 3 days after the end of the intervention
Extracellular, intracellular and total body water (L) will be estimated by bioimpedance
At baseline, during the ten days of intervention and until 3 days after the end of the intervention
Change in calf and thigh circumferences
Time Frame: At baseline, during the intervention period and until 3 days after the intervention period
Change in calf and thigh circumferences will be measured using a measuring tape (cm)
At baseline, during the intervention period and until 3 days after the intervention period
Change in fat and lean body mass measured by dual energy x-ray absorptiometry (DEXA)
Time Frame: At baseline, after 10 days of dry-immersion and 10 days of reovery
Change in fat and lean body mass (g) measured by dual energy x-ray absorptiometry (DEXA)
At baseline, after 10 days of dry-immersion and 10 days of reovery
Change in Resting Metabolic Rate (RMR)
Time Frame: At baseline, at day 3 and day 9 days of intervention periods
RMR (kcal/24h) will be measured by indirect calorimetry technique
At baseline, at day 3 and day 9 days of intervention periods
Change in nitrogen balance
Time Frame: At baseline, at day 3 and day 9 days of intervention periods
Nitrogen balance is a measure of nitrogen input minus nitrogen output. Nitrogen intake (g) is calculated with a nutrition software. Total urinary nitrogen (g) in the 24-Hour urine collection estimates nitrogen output
At baseline, at day 3 and day 9 days of intervention periods
Change in glucose tolerance (Oral Glucose Tolerance Test)
Time Frame: At baseline, at day 3 and day 9 days of intervention periods
Glucose (mmol/L) levels will be measured at baseline (fasting) and 30, 60, 90, 120 and 180 minutes after drinking within 5 min a water solution containing 75 g of glucose
At baseline, at day 3 and day 9 days of intervention periods
Change in serum bone formation marker (bone-specific Alkaline Phosphatase bAP)
Time Frame: At baseline and during the 10 days of interventions
Change in bone-specific Alkaline Phosphatase (bAP, µg/L) will be assessed by chemiluminescence immunoassay
At baseline and during the 10 days of interventions
Change in serum bone resorption marker (C-terminal cross-linked telopeptide of type I collagen CTx)
Time Frame: At baseline and during the 10 days of interventions
Change in C-terminal cross-linked telopeptide of type I collagen (CTx, pmol/L) will be assessed by chemiluminescence immunoassay will be assessed by enzyme-immmuno assay
At baseline and during the 10 days of interventions
Changes in bone density (by DEXA and High Resolution Peripheral Computed Tomography (HR-pQCT))
Time Frame: At baseline and at day 10 of intervention periods
Bone density (g/cm2) is measured at lumbar and hip level with DEXA and at tibia and radius level with HR-pQCT. Additionally tibia mechanical properties will be estimated by cortical ultrasound propagation velocity (m/s) via intraosseous ultrasonography.
At baseline and at day 10 of intervention periods
Change in serum cartilage synthesis biomarkers
Time Frame: At baseline, during the intervention period and until 3 days after the intervention period
Change in serum CP II and in human cartilage glycoprotein-39 (YKL-40) concentrations
At baseline, during the intervention period and until 3 days after the intervention period
Change in serum cartilage degradation biomarkers
Time Frame: At baseline, during the intervention period and until 3 days after the intervention period
Change in serum Cartilage Oligomeric Matrix Protein (COMP) and fragments or propeptide of type II collagen (C2C, C1,2C, Coll-2-1) concentrations
At baseline, during the intervention period and until 3 days after the intervention period
Change in muscle strength
Time Frame: At baseline and after one day of recovery
Muscle strength will be assessed from single leg isometric maximal voluntary contraction on the knee extensors & flexors, the plantarflexors and dorsiflexors. The Isometric Torque will be measured in Nm. The peak of the three maximal attempts will be recorded for strength measures
At baseline and after one day of recovery
Changes in jump performance
Time Frame: At baseline and the first day of recovery
Jump performance will be assessed on a platform and height of the jump will be evaluated
At baseline and the first day of recovery
Change in contraction time
Time Frame: At baseline and at the end of the intervention periods
Contraction time will be assessed during a measurement using the tensiomyography method in the following muscles: vastus lateralis, Gastrocnemius medialis and Biceps femoris of dominant leg.
At baseline and at the end of the intervention periods
Change in standing balance
Time Frame: At baseline and at day 1 and day 2 of recovery
Standing balance (CoP velocity, mm/s) will be assessed by posturography eyes open and eyes closed on a platform covered with 12-cm thick medium density foam
At baseline and at day 1 and day 2 of recovery
Change in walking balance
Time Frame: At baseline and after 10 days of intervention and day 1 after the end of the intervention
Functional mobility test (such as sit and walk, heel to toe steps with eyes closed and open, Triangle Completion Task) will assess walking balance.
At baseline and after 10 days of intervention and day 1 after the end of the intervention
Change in height
Time Frame: At baseline and at day 1, day 2 and day 3 of recovery
Change in height (mm) measured in standing position
At baseline and at day 1, day 2 and day 3 of recovery
Change in mid cerebral artery (MCA) blow flow velocity
Time Frame: At baseline and one day after the intervention period
Mid cerebral artery (MCA) blow flow velocity will be measured by transcranial Doppler
At baseline and one day after the intervention period
Change in circadian rhythms of blood pressure
Time Frame: At baseline and during the ten days of the intervention periods
Continuous 24-h recording of systolic and diastolic blood pressure will be performed by a Non Invasive Blood Pressure system (SOMNOtouch™NIBP) designed for ambulatory continuous measurements
At baseline and during the ten days of the intervention periods
Change in mood
Time Frame: At baseline, at day 5 of the intervention period and 3 days after the end of the intervention
Change in mood is assessed using the Profile of Mood States (POMS) questionnaire, by calculation of total mood disturbance (scale from -32 to 200, a higher score indicates more severe mood disturbance)
At baseline, at day 5 of the intervention period and 3 days after the end of the intervention
Change in affective states
Time Frame: At baseline, at day 5 of the intervention period and 3 days after the end of the intervention
Positive and Negative Affect Schedule (PANAS) questionnaire will be used to assess the intensity of positive (range from 10 to 50, with higher scores representing higher levels of positive affect) and negative (range from 10 to 50, with lower scores representing lower levels of negative affects) affective states. PANAS self-report questionnaire consists of two 10-item scales to measure both positive and negative affects.
At baseline, at day 5 of the intervention period and 3 days after the end of the intervention
Change in sleep quality
Time Frame: Daily from baseline to 10 days after the end of the intervention

Pittsburgh Sleep Dairy (PghSD) will be used to assess sleep perceived quality. The PghSD is an instrument with separate components to be completed at bedtime and waketime. The following parameters are registered or assessed:

Bedtime, waketime, sleep latency, wake after sleep onset, total sleep time, mode of awakening and ratings of sleep quality, mood, and alertness on wakening, as well as daytime information on naps, exercise, meals and caffeine, tobacco and medications use.
Daily from baseline to 10 days after the end of the intervention
Change in psychological state: mental health
Time Frame: At baseline, at day 5 of the intervention period and 4 days after the end of the intervention

ical well-being and capture distress

GHQ-28 gives an overall total score and 4 scores for 4 subscales:

Somatic symptoms, Anxiety/insomnia, Social dysfunction, Severe depression. Higher scores indicate higher levels of distress
At baseline, at day 5 of the intervention period and 4 days after the end of the intervention
Change in coping strategies
Time Frame: At day 5 of the intervention and 2 days after the end of the intervention

Brief Cope Questionnaire is designed to measure effective and ineffective ways to cope with a stressful life event, and will be used to assess coping strategies. The Brief Cope is a shortened form (28 items) of the Carver and Scheier COPE inventory.

There are 14 coping strategies. These strategies can be then gathered in two main categories : approach coping and avoidance coping.
At day 5 of the intervention and 2 days after the end of the intervention
Measurement of changes in subjective sleepiness
Time Frame: At baseline, at day 4 and 8 of the intervention period and 3 days after the end of the intervention
Changes in subjective level of sleepiness will be measured using the Karolinska sleepiness scale (KSS) two times per day, with a scale from 1 to 10 (higher scores reprensent higher sleepiness).
At baseline, at day 4 and 8 of the intervention period and 3 days after the end of the intervention
Change in circadian variations of heart rate
Time Frame: At baseline, at day 1, day 4, day 7 of intervention, and at first day of recovery
Difference between day-time and night-time heart rate (bpm) will be calculated
At baseline, at day 1, day 4, day 7 of intervention, and at first day of recovery
Change in daily body movements
Time Frame: Continuously from baseline until 5 days after the intervention period
Accelerometry-derived daily physical activity counts will be quantified using actigraph GT3X+
Continuously from baseline until 5 days after the intervention period
Dynamics of body fluids during the 4 first hours of exposure
Time Frame: The 4 first hours of Dry Immersion / Bed Rest
Changes from pre to 240 min of exposure for plasma volume percentage versus baseline (%) assessed by the Dill and Costill method
The 4 first hours of Dry Immersion / Bed Rest
Lower limb vascular properties
Time Frame: At baseline, at day 10 of intervention periods, and day 3 of recovery
Change in tibial intracortical blood flow velocity (mm/s), induced by physiological maneuvers (velocity of intracortical blood flow at medial tibia level and its responses to vascular occlusion will be assessed via Ultrasound Vector Flow Mapping)
At baseline, at day 10 of intervention periods, and day 3 of recovery
Myofiber atrophy
Time Frame: At baseline and at day 8 of intervention
Biopsy sampling from m. vastus lateralis will be performed. Myofiber CSA related to fiber type (µm2) will be measured by morphometric analysis.
At baseline and at day 8 of intervention
Post-occlusive reactive hyperemia at great toe and thumb level
Time Frame: At baseline and 4 days after the end of the intervention
Blood flow (AU) will be assessed via Laser Doppler flowmetry. Post-occlusive reactive hyperemia index will be calculated.
At baseline and 4 days after the end of the intervention
Quantitative sensory testing at the dorsum of the foot (vibration detection threshold)
Time Frame: At baseline, at day 7 of intervention periods, and day 2 of recovery
Vibration detection threshold (s) will be measured using graded tuning fork
At baseline, at day 7 of intervention periods, and day 2 of recovery
Whole-body MRI
Time Frame: At baseline, at day 9 of intervention periods
Change in MRI-measured whole-body Lean mass (kg) and Fat mass (kg) will be estimated
At baseline, at day 9 of intervention periods
Vestibular health evaluation
Time Frame: At baseline and the first day of recovery
Battery of tests routinely performed on astronauts will be used. Sit-to-stand time (s) will be quantified.
At baseline and the first day of recovery
Blood cytokines evolution
Time Frame: At baseline, at day 3 & 10 of intervention periods, and day +10 of recovery
To characterize immune functions, the following blood cytokines (pg/ml) will be assessed: TPO, G-CSF, IL-1β, IL-1Ra, IL-4, IL-6, IL-8, IL-10, IFNy, TNF
At baseline, at day 3 & 10 of intervention periods, and day +10 of recovery
Salivary cortisol evolution
Time Frame: At baseline, at day 1, 3 & 10 of intervention periods, and day +4 & +10 of recovery
To characterize stress level, morning and evening salivary cortisol (ng/ml) will be assessed
At baseline, at day 1, 3 & 10 of intervention periods, and day +4 & +10 of recovery
Change in optic nerve sheath diameter (ONSD) considered as an indirect marker for intracranial pressure (ICP) estimation
Time Frame: From baseline to 1 day after the end of the intervention
The optic nerve sheath diameter (ONSD) variations will be measured by echography
From baseline to 1 day after the end of the intervention
Change in intraocular pressure (IOP)
Time Frame: From baseline to 1 day after the end of the intervention
IOP measured by applanation
From baseline to 1 day after the end of the intervention
Change in visual acuity
Time Frame: At baseline and 2 days after the intervention period
Far and near visual acuity are tested uncorrected, or if applicable with own correction with digital acuity system
At baseline and 2 days after the intervention period
Change in visual field
Time Frame: At baseline and 2 days after the intervention period
Visual field measured by standard automated perimetry
At baseline and 2 days after the intervention period
Change in the anatomical characteristics of the eye (optical biometry)
Time Frame: At baseline and 2 days after the intervention period
Optical biometry measured by partial coherence interferometry
At baseline and 2 days after the intervention period
Change in the central corneal thickness
Time Frame: At baseline and 2 days after the intervention period
Central corneal thickness on a single point on the cornea measured by Ultrasonic pachymetry
At baseline and 2 days after the intervention period
Change in the retina by non-mydriatic fundus retinography
Time Frame: At baseline and 2 days after the intervention period
Non-mydriatic fundus retinography allows a fundus photography to be taken and thus a color image of the papilla, retinal vessels and macula
At baseline and 2 days after the intervention period
Change in the cornea topography
Time Frame: At baseline and 2 days after the intervention period
Cornea topography measured by corneal topography equipment (like Pentacam). The elevation topography according to Scheimpflug principle allows the mapping of the anterior and posterior surface of the cornea.
At baseline and 2 days after the intervention period
Change in cerebral structures and in venous circulation of the brain by MRI
Time Frame: At baseline and at day 9 of intervention
Visualization of cerebral structures and intracranial venous system will be performed by MRI coupled with injection of gadolinium
At baseline and at day 9 of intervention
Change in thrombotic and fibrinolytic processes
Time Frame: At baseline, during the intervention and 2 days after the intervention period
Thrombotic and fibrinolytic processes will be assessed by thromboelastometry (TEM, coagulation analyzer from Matel Medizintechnik, Graz, Austria), providing a kinetic analysis of the clot formation process and of clot dissolution by the fibrinolytic system. Clotting time (min) wil be measured.
At baseline, during the intervention and 2 days after the intervention period
Change in energy requirements
Time Frame: At baseline and at day 2 of the intervention period
Change in energy requirements using the doubly labelled water
At baseline and at day 2 of the intervention period
Change in skin microcirculation
Time Frame: At baseline and 3 days after the intervention period
Indirect evaluation of cardiovascular and neurovascular change by performing deep inspiration. Blood flow (AU) at great toe will be assessed via Laser Doppler flowmetry. Inspiratory gasp vascular response (%) will be calculated.
At baseline and 3 days after the intervention period
Change in cardiovascular deconditioning and orthostatic tolerance (stand test)
Time Frame: At baseline and 2 days after the intervention period
This test continuously measures heart rate (bpm) via a Finapres device while subjects sit for 5 minutes, then stand for 5 minutes and then sit again for 5 minutes
At baseline and 2 days after the intervention period
Change in stress and mental load
Time Frame: From baseline to 10 days after the end of the intervention
This test assesses the effects of dry immersion and bed rest on cognitive tasks involving various executive functions (e.g., attention, memory, decision-making) by assessing both physiological (via the SOMNO HD system) and behavioral parameters (e.g., emotions, cognitive load) using the D2 test of attention. Pourcentage of errors (%) will be measured as a qualitative aspect of performance.
From baseline to 10 days after the end of the intervention

Collaborators and Investigators

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

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Centre National d'Etudes Spatiales

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Marc-Antoine CUSTAUD, MD, PhD, University Hospital, Angers

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)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
December 9, 2024

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
April 23, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
April 23, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
December 20, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
January 10, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
January 15, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 6, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 5, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
May 1, 2025

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 24-336
  • 2024-A02109-38 (Other Identifier: Agence Nationale de Sécurité du Médicament et des Produits de Santé (ANSM))

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

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.

Cookie Settings

We use cookies to ensure that we give you the best experience on our website. For more details carefully read our Privacy and Cookies Policy. ...>>>You can change your preferences or withdraw your consent at any time by deleting the cookies from your website or computer as described in the policy. Please accept it and choose your preferences by ticking the corresponding boxes in the "Manage Settings" section below. Please carefully read our Terms of Service before you proceed with using any part of this website.
«Manage Settings