A 60 Days Head Down Tilt Bedrest With Artificial Gravity and Cycling Exercise on 24 Healthy Male (BRACE)

NCT06544213 | Active Not Recruiting

• 2 other identifiers: 20-2422022-A02074-39
• Study Type: interventional
• Target: 24
• Locations: 1 country
• Sites: 1

Brief Summary

The objective of this study is to investigate whether a cycling exercise coupled with artificial gravity via a short-arm human centrifuge helps to prevent and / or reduce the deleterious effects induced by 60 days of anti-orthostatic bedrest. The secondary objective is to investigate whether the combination of a supine cycling exercise with artificial gravity is more effective than the same supine cycling exercise alone in preventing or reducing the effects of head-down bedrest. During a randomized, 60 day bed rest study, in 24 healthy male adults, the two following aims will be undertaken:

• Fourteen scientific protocols will assess the changes in the cardiovascular, metabolic, musculoskeletal, neuro-sensorial, haematological, and immunological systems.
• In the above-mentioned systems, the comparative potential beneficial effects of the two countermeasure protocols will also be investigated by the scientific protocols and bedrest standard measurements (BSM).

Conditions

Simulated Microgravity by Head Down Tilt Bedrest; Weightlessness

Keywords

Simulation of microgravity; Weightlessness; Artificial Gravity; Bedrest; Countermeasure

Outcome Measures

Primary Outcomes (29)

• Changes in orthostatic tolerance

  Orthostatic tolerance will be assessed during a tilt test combined with Lower Body Negative Pressure test (LBNP test)

  At baseline and first day of recovery

• Changes in peak aerobic power (VO2max test)

  Exercise capacity wil be assessed by graded cycling on sitting ergometer until exhaustion

  At baseline and end of head down tilt phase at week 10

• Changes in plasma volume

  Plasma volume (L) will be assessed by the carbon monoxide-rebreathing method

  At baseline and end of head down tilt phase at week 10

• Changes in serum bone formation markers

  Change in bone-specific Alkaline Phosphatase (bAP, µg/L) and procollagen type I N-terminal propeptide (P1NP, µg/L) will be assessed by chemiluminescence immunoassay

  From baseline until the end of the volunteers' participation in the study at year 2

• Change in serum bone resorption markers

  Change in C-terminal cross-linked telopeptide of type I collagen (CTx, pmol/L) and N-terminal cross-linked telopeptide of type I collagen (NTX, pmol/L) will be assessed by chemiluminescence immunoassay.

  From baseline until the end of the volunteers' participation in the study at year 2

• Changes in Resting Metabolic Rate (RMR)

  RMR will be measured by indirect calorimetry technique

  At baseline and at recovery at week 12

• Change in nitrogen balance

  Nitrogen balance is a measure of nitrogen input minus nitrogen output. Nitrogen intake is calculated with a nutrition software. Protein oxidation measured in the 24-Hour urine collection estimates nitrogen output.

  At baseline and at recovery at week 12

• Change in muscle strength

  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 at recovery at week 10

• Change in fat and lean body mass measured by dual energy x-ray absorptiometry (DEXA)

  Dual energy x-ray absorptiometry is a standard clinical technique to assess fat (g) and lean (g) body mass.

  From baseline until the end of the volunteers' participation in the study at year 2

• Change in walking balance

  Functional mobility test (such as sit and walk, heel to toe steps with eyes closed and open) will assess walking balance

  At baseline and at recovery at week 10

• Changes in jump performance

  Jump performance will be assessed on a platform and height of the jump will be evaluated

  At baseline and at recovery at week 12

• Change in standing balance

  Standing balance 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 recovery at week 10

• Changes in leg muscle volume and fat

  MRI of the lower extremity will assess the degree of atrophy and changes in fat content in the musculature

  At baseline and at recovery at week 10

• Changes in bone density (by DEXA and High Resolution Peripheral Computed Tomography (HR-pQCT))

  Bone density is measured at lumbar and hip level with DEXA and at tibia and radius level with HR-pQCT

  From baseline until the end of the volunteers' participation in the study at year 2

• Change in the optic nerve fibers thickness

  Thickness of the optic nerve fibers will be measured by Optical Coherence Tomography (OCT)

  At baseline and at recovery at week 12

• Change in intraocular pressure (IOP)

  IOP is measured with air tonometry

  At baseline and at recovery at week 12

• Change in visual acuity

  Far and near visual acuity are tested uncorrected, or if applicable with own correction with digital acuity system

  At baseline and at recovery at week 12

• Change in visual field

  Visual field measured by standard automated perimetry

  At baseline and at recovery at week 12

• Change in the anatomical characteristics of the eye (optical biometry)

  Optical biometry measured by partial coherence interferometry

  At baseline and at recovery at week 12

• Change in the central corneal thickness

  Central corneal thickness on a single point on the cornea measured by Ultrasonic pachymetry

  At baseline and at recovery at week 12

• Change in the retina by non-mydriatic fundus retinography

  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 at recovery at week 12

• Change in the cornea topography

  Cornea topography measured by corneal topography equipment (like Pentacam). The elevation topography allows the mapping of the anterior and posterior surface of the cornea.

  At baseline and at recovery at week 12

• Change in motion sickness susceptibility

  Assessed by the Motion Sickness Susceptibility Questionnaire Short form (MSSQ-Short). MSSQ-Short scores possible range from minimum 0 to maximum 54, the maximum being unlikely. Higher scores means a higher motion sickness susceptibility

  At baseline and at recovery at week 12

• Change in fluid shift distribution towards the cardiac and cephalic region

  The consequences of the fluid shift on the cardiac and cephalic area will be assessed by quantifying the right and left Jugular veins volumes (mL), as well as the left ventricle diastolic/systolic volumes (mL) by ultrasound.

  At baseline and until year 1

• Change in mood

  Change in mood is assessed using the Profile of Mood States (POMS) questionnaire. POMS questionnaire gives 6 measures of mood: Tension/anxiety, Depression, Anger/hostility Dynamism, Fatigue, Confusion A Total Mood Disturbance (TMD) score is calculated by summing the totals for the negative subscales (tension, depression, fatigue, confusion, anger) and then subtracting the totals for the positive subscale (vigor /esteem-related affect).

  At baseline and until week 12

• Change in affective states

  Positive and Negative Schedule (PANAS) questionnaire will be used to assess the intensity of positive and negative affective states. PANAS self-report questionnaire consists of two 10-item scales to measure both positive and negative affects Each item is rated on a five-point Likert Scale, ranging from 1 = Not at all to 5 = Extremely, to measure the extent to which the affect has been experienced in a specified time frame. Positive affects: scores can range from 10 - 50 with higher scores representing higher levels of positive affect. Negative affects: scores can range from 10 - 50 with higher scores representing higher levels of negative affect.

  At baseline and until week 12

• Change in sleep quality

  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 wake time. The following parameters are registered or assessed: Bedtime, wake time, 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.

  At baseline and until week 12

• Change in psychological state: mental health

  General Health Questionnaire-28 (GHQ-28) will be used to assess psychological 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 and until week 12

• Measurement of changes in subjective sleep quality

  Changes in subjective sleep quality will be measured using the Karolinska sleepiness scale (KSS) two times per day (bed time) every week.

  At baseline and until week 12

Secondary Outcomes (4)

• Change in vertebral bone marrow fat fraction.

  At baseline and until year 1

• Changes in myokinins.

  At baseline and until week 12

• Changes in brain structure

  At baseline and until week 12

• Change in pulse wave velocity in carotid and femoral arteries

  At baseline and until year 1

Study Arms (3)

Control Group

EXPERIMENTAL

Control group does not receive any countermeasure program during the head down tilt phase.

Behavioral: Control Group

Artificial Gravity and Supine Bike

EXPERIMENTAL

The volunteers in this group receive countermeasure exercises during the head down tilt phase. 6 days over 7, they will perform a 30 minutes exercises on a supine bike (incremental steps) combined with artificial gravity generated with a short arm centrifuge.

Behavioral: Countermeasure AG-Bike

Supine Bike

EXPERIMENTAL

The volunteers in this group receive countermeasure exercises during the head down tilt phase. 6 days over 7, they will perform a 30 minutes exercises on a supine bike (incremental steps).

Behavioral: Countermeasure Supine Bike

Interventions

Control Group BEHAVIORAL

60 days of strict head down tilt bed rest at all time. No countermeasure program is performed.

Control Group

Countermeasure Supine Bike BEHAVIORAL

60 days of strict head down tilt bed rest at all time. The exercise starts at 40% of VO2max for 5 minutes, followed by a series of 2-minute high- and low-intensity intervals for 20 minutes. 2-minute high-intensity intervals are at 65% VO2max, 70% VO2max, 80% VO2max, 80% VO2max, 70% VO2max and 65% VO2max. 2-minute low-intensity intervals are at 40% VO2max. 3 minutes at 40% of VO2max will end the exercise. VO2max is measured for each volunteer in supine position.

Supine Bike

Countermeasure AG-Bike BEHAVIORAL

60 days of strict head down tilt bed rest at all time. The exercise starts at 40% of VO2max for 5 minutes, followed by a series of 2-minute high- and low-intensity intervals for 20 minutes. 2-minute high-intensity intervals are at 65% VO2max, 70% VO2max, 80% VO2max, 80% VO2max, 70% VO2max and 65% VO2max. 2-minute low-intensity intervals are at 40% VO2max. 3 minutes at 40% of VO2max will end the exercise. VO2max is measured for each volunteer in supine position. The supine bike exercise is performed in a short arm centrifuge in rotation. Volunteers will start pedalling and the centrifuge will start at 0.15 Gz less than individual's threshold. Every 4 minutes thereafter, the AG will be increased by 0.15 Gz, synchronized with the ramping up of cycle ergometer interval intensity. The AG will increase only up to 70 % of their tolerance level,. It will then decrease by 0.15 Gz every 4 minutes, and until the 30-minute exercise is completed.

Artificial Gravity and Supine Bike

Eligibility Criteria

• Age: 20 Years - 45 Years
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy male volunteer (see below the description of medical tests and laboratory analysis performed at the selection visit)
• Aged 20 to 45 years
• No overweight nor excessive thinness with BMI (weight kg/ height m2) between 20 and 27 kg/m2
• Height between 158 and 190 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, of the ear, nose, throat (especially orthostatic hypotension and vestibular disorders), orthopaedic or musculoskeletal disorders
• Good mental health: tests and psychological interview will be held by a specialist in extreme environment
• Fitness level assessment: 35 mL/min/kg \< VO2max \< 55 mL/min/kg
• Non active smokers
• No alcohol or drug dependence, and no medical treatment
• Covered by a Health Insurance System
• Having signed the information consent
• Free of any engagement during the study

You may not qualify if:

• Any history or presence of clinically relevant cardiovascular, neurological or ear, nose, throat disease, 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 systolic blood pressure 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,
• Vestibular disorders
• History of migraines,
• History of hiatus hernia or gastro-esophageal reflux,
• History of thyroid dysfunction, renal stones, diabetes,
• History of head trauma,
• Abnormal result for lower limbs echo-doppler,
• History of genetic muscle and bone diseases of any kind,

Sponsors & Collaborators

• Centre National d'Etudes Spatiales: lead
• European Space Agency: collaborator
• MEDES - IMPS: collaborator

Study Sites (1)

MEDES-Institut de Médecine et Physiologie Spatiale

Toulouse, France, 31400, France

Location

MeSH Terms

Interventions

Control Groups

Intervention Hierarchy (Ancestors)

Epidemiologic Research Design; Epidemiologic Methods; Investigative Techniques; Research Design; Methods

Study Officials

• Rebecca Billette de Villemeur

  MEDES - Institut de Médecine et Physiologie Spatiale

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Masking Details: Participants and investigators are aware of the groups distribution
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER GOV
• Responsible Party: SPONSOR

Model Details: Volunteers are divided in three groups (8 volunteers each), one control group, one group with supine bike as countermeasure, one group with artificial gravity and supine bike as countermeasure

Study Record Dates

• First Submitted: July 25, 2024
• First Posted: August 9, 2024
• Study Start: February 6, 2023
• Primary Completion: April 20, 2024
• Study Completion: April 30, 2026
• Last Updated: December 18, 2025

Record last verified: 2025-12

Locations

FR (1)