Healthy Subjects
Conditions
Interventions
Group 1: 60 days of bedrest in a 6° Head-Down Tilt position (HDTBR) + electrical muscles
Group 2: 60 days of bedrest in a 6° Head-Down Tilt position (HDTBR) + proprioceptive training (PT)
Group 3: 60
Sponsors
DLR-Institut für Luft- und Raumfahrtmedizin (German Aerospace Center, Institute of Aerospace Medicine)
Eligibility
Sex/Gender
All
Age
24 Years to 55 Years
Inclusion criteria
Inclusion criteria: Physically and mentally healthy test subjects that declare their willingness to participate in the entire study and successfully pass the psychological and medical screening: • Aged between 24 and 55 years • Body mass index between 18 to 28 kg/m2 • Body height between 153 to 190 cm (+/- 2 cm) • Signed informed consent • Demonstrable medical insurance and official certificate of absence of criminal record • No less than 2 SD below the average normal bone mineral density (measured by dualenergy x-ray absorptiometry) for hip and lumbar spine (i.e., mean peak bone mineral density of Caucasian, sex-matched young adults) denoted by T-score (T-score > -2) • Demonstrable dentist certificate • Hormonal contraception for female participants is allowed, but details (manufacturer, doses, dates) must be reported
Exclusion criteria
Exclusion criteria: Candidate subject exclusion criteria for the study will include the following: • Any infectious, genetic, autoimmune, endocrinological, hematological, cardiovascular, lung, gastroenterological, kidney, rheumatic, muscle, bone, orthopedic, dermatological, gynecological, urological, ophthalmological, otorhinolaryngological, neurological or psychiatric disease* that precludes a safe participation in the study or might significantly impact scientific results of the study according to the study physician • Drug, medication or alcohol abuse (regular consumption of more than 30 g alcohol/day) • Smoker within 6 months prior to enrollment • Any long-term medication use that might significantly impact scientific results of the study (for instance bisphosphonate therapy, anti-hypertensives, gastro-esophageal reflux). • Special dietary requests, that cannot be provided by the project team (e.g. vegan, vegetarian or other ineligible diet) • Claustrophobia • Increased intraocular pressure Sensorimotor Countermeasures Study 38 SMC Ethics File Version 2 – January 2024 • Hyperopia / Myopia > +/- 5.0 Diopters • Astigmatism > 3 Diopters • History of laser surgery of the eye, glaucoma and retinal surgery • Any ocular condition that would significantly impact visual function • Significant chronic gastro-esophageal reflux precluding a safe participation in the study • Clinically relevant allergy (e.g. requirement to carry a stand-by emergency injection), that precludes a safe participation in the study • History of chronic back complaints, that precludes a safe participation in the study • History of kidney stones • Anemia: Hemoglobin under normal values**. (Normal values of Hemoglobin for men: 13.0- 17.5 g/dl; women 12.0-16.0 g/dl) • Elevated risk of thrombosis*** • Inability to successfully complete a 10-minute upright posture test without clinically relevant orthostatic symptoms • Current or history of hemorrhagic diathesis or coagulations disorders • History of spinal cord disease, including radiculopathy, myelopathy, or neuropathy • History of disorders affecting CSF circulation (i.e. hydrocephalus, idiopathic intracranial hypertension) • History of more than one depressive episode and/or history of a severe depressive episode, such as requiring inpatient or intensive outpatient treatment • Known chronic tinnitus • Hearing loss (bi-lateral or one-sided) precluding successful participation in the study • Female candidate is pregnant or breast-feeding • Female candidate is in menopause or post-menopause, unless on hormone replacement therapy (but not treated with bisphosphonates or anti-resorptives) • Female candidate stopped hormonal contraception medication up to 3 months prior to study start • Metal implants (or objects like metallic slivers in the eyes, or bullets or shrapnel in the body) or other kinds of bone synthesis materials, implanted medical devices, tattoos or permanent make-up incompatible with MRI • Participation in a (clinical) study within the last 3 months before start of this study that significantly confounds participation in the study • Any other condition which makes the test subject unsuitable for study inclusion in the opinion of the project team
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| The primary outcome measure will be the time to complete the Foam Obstacle Course Test. This test will be performed before and after HDTBR and differences in time to complete the Foam Obstacle Course Test following HDTBR will be used to determine countermeasure success and estimate the potential efficacy for spaceflight operations. | — |
Secondary
| Measure | Time frame |
|---|---|
| Additional functional tasks with similarly high demand for dynamic postural and locomotor control will also be tested before and after HDTBR - for the recovery from fall test, we will compare stand time and postural sway - for the Object Translation Test, we will use time to complete as the main outcome measure - for the jump down test, we will compare postural settling time (s), defined as time between touchdown and quiet stance, as a metric of how quickly the postural control system can recover from a jump-induced perturbation. | — |
Countries
Germany
Contacts
Public ContactAndrea Nitsche
DLR-Institut für Luft- und Raumfahrtmedizin (German Aerospace Center, Institute of Aerospace Medicine)
Outcome results
None listed