In the current study the investigators will study early biomarkers of human degradation. In 10-day horizontal bed rest the investigators will enroll 10 healthy male subjects (18-30years, BMI 20-28kg/m2). Pre-, mid- and post-bed rest the investigators will perform various measurements, some of them will be invasive (blood samples and muscle biopsies), which will be carefully taken by the medical staff. The subjects will be placed in hospital rooms and have 24-hour medical supervision, adequate hygiene, nutrition, passive exercise, entertainment and visits.
Ten young male participants will undergo 10 days of horizontal bed rest. Before, during and after the investigators will monitor many biomechanical, metabolic, cardiovascular, biochemical responses. During the bed rest period there will be no interventions. subjects will be allowed to rotate freely, with no vertical stimulus of any-kind.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
10
10-day of complete bed rest
Splosna bolnisnica Izola (Hospital of Izola)
Izola, Slovenia
Change in mittochondria respiration rate
Change in Mittochondria oxygen respiration rate per mg of muscle tissue after 10-day bed rest
Time frame: At baseline and after 10-day bed rest
Change in skeletal muscle single fibre force (in micro Newtons)
In each aprticipants at each time point approx 10 intact muscle fibres will be studied for their force production after 10-day bed rest. Isometric muscle fibre force (in mNewton) will be measured isometric force (Fo) in four subsequent maximal activations (pCa, 4.6; sarcomere length, 2.6 micrometers; temperature 12 degrees C) using an electrical motor with force transducer mounted on it.
Time frame: At baseline and after 10-day bed rest
Change in Neurological outcomes - nerve conduction velocity
Change in nerve conduction velocity after 10-day bed rest
Time frame: At baseline and after 10-day bed rest
Change in Neurological outcomes - fMRI
Change in ability to mentally imagine/perform locomotory tasks (voxel-based network analyses) after 10-day bed rest
Time frame: At baseline and after 10-day bed rest
Change in Neurological outcomes - neurocognitive assessment
Change in EEG and neurocognitive tasks parameters (event related potential; P300 component during Stroop task) after 10-day bed rest
Time frame: At baseline and after 10-day bed rest
Change in skeletal muscle NCAM expression in single fibres
Neural cell adhesion molecule (NCAM) expression will be analysed in vastus lateralis biopsy samples at three time points.
Time frame: Before, at day 5 and day 10 of bed rest
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Change in muscle volume after 10-day bed rest
Thigh muscle volume will be assessed by continous section obtained by 3T MRI. Muscle segmentation will done by Matlab routine.
Time frame: At baseline and after 10-day bed rest
Change in peak aerobic power after 10-day bed rest
Change in peak aerobic power (maximal oxygen consumption) will be assessed on a cycloergometer using graded load protocol.
Time frame: At baseline and after 10-day bed rest
Nonhomogeneous change in skeletal muscle pennation angle after 10-day bed rest
Change in Muscle architecture will be assessed in vastus lateralis, biceps femoris, tibialis anterior, multifidus using sonography. Specifically, we will assess all three architecture parameters (pennation angle, fascicle length and thickness), however for the purspose of this outcome we hypothesize non-homogenous change throughout the whole muscles in pennation angle. The assessment will be performed before, every 2 days of bed rest and post bed rest.
Time frame: At baseline, every 2 days of bed rest and after 10-day bed rest
Change in maximal displacement after twitch contraction after 10-day bed rest
Using tensiomyography we will assess contraction time and maximal discplacement in vastus lateralis, tibialis anterior, biceps femoris, multifidus muscles. We expect that contraction time will remained the same but maximal diasplacement - a measure of a muscle tone, will increase much before the changes in muscle thickness - assessed by sonography. The assessment will be performed before, every 2 days of bed rest and post bed rest.
Time frame: At baseline, every 2 days of bed rest and after 10-day bed rest
Change in skeletal composition after 10-day bed rest
Using electrophoresis we will assess changes in myosing heavy chains somposition in the biopsies obtained from vastus lateralis muscle before, at day 5 and post 10 days of bed rest
Time frame: At baseline, day 5 and after 10-day bed rest
Change in skeletal muscle maximal voluntary contraction after 10-day bed rest
Maximal voluntary isometric knee extensors contraction will be measured using dnamometer set at 90 deg flexion.
Time frame: At baseline and after 10-day bed rest
Change in balance after 10-day bed rest
Change in static and dynamic balance will be assessed by functional tests (gait assessed with Optogait system and balance assessed with Tensiometric plate-COP) after 10-day bed rest
Time frame: At baseline and after 10-day bed rest
Change in orthostatic tolerance after 10-day bed rest
Change in mean arterial pressure during supine-to-stand test (mmHg) will be assessed by supine to stand test, where subjects will stay 10 minutes in each position.
Time frame: At baseline and after 10-day bed rest