Medium-term Bedrest Whey Protein (MEP)
- Conditions
- Countermeasure Evaluation
- Interventions
- Dietary Supplement: Whey Protein + Potassium bicarbonateOther: Control
- Registration Number
- NCT01655979
- Lead Sponsor
- DLR German Aerospace Center
- Brief Summary
The human being has shown that he can live and work in the space environment, but due to the lack of essential mechanical load on muscle and bone, the fluid-shift as well as alterations in the acid-base balance (mainly on account of nutritional factors), the exposure to microgravity results in a gradual degradation of muscle, bone and cartilage, deconditioning of the cardiovascular system and metabolic changes. Countermeasures to prevent all the deconditioning of the physiological systems are not yet fully effective and require further investigation.
A commonly utilized model of simulating the physiological effects of microgravity on the human organism on ground is the 6° head-down-tilt bed rest. In the present study the model has been used to study potential countermeasures to spaceflight-associated deconditioning.
One of the most constrictive changes appearing during space flight as well as during bed rest, are disuse-induced muscle losses. These are associated with a decrease in muscle protein synthesis, rather then an increase in muscle protein breakdown. Besides an effective training countermeasure, nutritional countermeasures gain respect in this context: supplementing conventional diets with whey protein or essential amino acids has been shown to increase muscle protein synthesis. Due to these anabolic properties whey protein seems promising to counteract disuse-induced muscle wasting.
Drawbacks of a high protein intake are calciuric effects, ascribed to the proton-release when metabolizing sulfur-containing amino acids. The so called 'low grade metabolic acidosis' has also shown to activate osteoclastic bone resorption and muscle protein degradation. Therefore, to maximize the anabolic potential of a whey protein supplementation, the acidogenic properties need to be compensated. As previous works suggest, a shift of acid base balance into the acid direction and the resulting changes in bone and protein turnover may be hindered by supplementing alkaline mineral salts.
In this regard, a mid-term bed rest study was performed in order to investigate the effect of a combined whey protein (0.6 g/kg body weight/day) and potassium bicarbonate (90 mmol/day) supplementation as a potential countermeasure to multiple physiological and metabolic alterations on the human body resulting from real and simulated microgravity.
- Detailed Description
Not available
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- Male
- Target Recruitment
- 10
- Healthy males, 20 -45 years
- BMI: 20 - 25 kg/m2
- Height: 158 - 190 cm
- Weight: 65 - 85 kg
- maximum relative oxygen uptake: 30 - 60 ml/min/kg
- non-smokers
- successful medical and psychological screening
- Willingness to participate in the entire study
- signed informed consent
- social insurance
- Clear criminal background check
- Abuse of drugs, medicine or alcohol
- Vegetarians, Vegans
- Migraines
- History of mental illness
- Claustrophobia
- History of: thyroid dysfunction, renal stones, diabetes, allergies, hypertension, hypocalcaemia, uric acidaemia, lipidaemia, hyperhomocysteinaemia
- Rheumatism
- Muscle-, Cartilage- or Joint Injuries
- Gastro-esophageal reflux disease, renal function disorder, Hiatus hernia
- Chronic back pain
- Bone diseases
- Herniated discs
- Achilles tendon injuries
- Cruciate ligament rupture or any other severe knee injury
- BMD more than 1.5 SD < t-score
- History of orthostatic intolerance or vestibular disorders
- Anaemia
- Vitamin D Deficiency
- Positive response in thrombosis screening
- Use of metallic implants, osteosynthesis material
- Porphyria, Blood dyscrasia
- HIV, Hepatitis
- Increased Inner Eye pressure
- Intolerance to local anesthetics
- Participation in another study up to three month before study onset
Study & Design
- Study Type
- INTERVENTIONAL
- Study Design
- CROSSOVER
- Arm && Interventions
Group Intervention Description MEP-1 Whey Protein + Potassium bicarbonate - MEP-1 Control - MEP-2 Whey Protein + Potassium bicarbonate - MEP-2 Control -
- Primary Outcome Measures
Name Time Method Change in body composition Baseline, after 21 days of bed rest
- Secondary Outcome Measures
Name Time Method Body mass Daily for a duration of 35 days Bone mineral density + content Baseline, after 21 days of bed rest Standing balance Baseline, after 21 days of bed rest Locomotion Baseline, after 21 days of bed rest Locomotion will be assessed by Dynamic Gait Index, specific parameters are: total Score and Subscore
Plasma Volume Baseline, after 21 days of bed rest Maximum volume of oxygen uptake Baseline, after 21 days of bed rest Isometric torque Baseline, after 21 days of bed rest During a an Isometric Maximum Voluntary Contraction Test on the knee extensors \& flexors, the plantarflexors and dorsiflexors, the elbow extensors \& flexors the Isometric Torque will be measured in Nm.
Muscle fatigue Baseline, after 21 days of bed rest Bone metabolism Baseline, after 2,5,14,21 days of bed rest, 1, 5, 14, 28 days after finishing bed rest Intracranial pressure Baseline, after 1,4, 7,10,13,14,15,16,17,18,19,20,21 days of bed rest,1,2,4 days after finishing bed rest Monitoring of Vitamin K status Baseline, after 2,5,14,21 days of bed rest, 1, 5 days after finishing bed rest Fat metabolism Baseline, after 21 days of bed rest Glucose metabolism Baseline, after 21 days of bed rest, 4 days after finishing bed rest Nitrogen balance Daily for a duration of 33 days Energy metabolism Baseline, after 21 days of bed rest Glucocorticoid activity Baseline, after 2,3,7,8,12,13,16,17 days of bed rest, 2,3 days after finishing bed rest Muscle metabolism Baseline, after 21 days of bed rest Acid base balance Baseline, after 2, 14, 21 days of bed rest, 5 days after finishing bed rest Sympathetic activity during orthostatic stress Baseline, after 21 days of bed rest Muscle sympathetic nerve activity is measured by MSNA recording by microneurography technique.
Visual Orientation Baseline, after 6,12,20 days of bed rest, 2,4 days after finishing bed rest Visual Orientation is assessed by 'Oriented Character Recognition Test' and Luminous Line Test. The main parameter is Score.
Plasma galanin and adrenomedullin responses during head up tilt test (orthostatic stress) Baseline, after 21 days of bed rest Cartilage metabolism and -thickness Baseline, after 2,3,5,7,14,21 days of bed rest, 5 days after finishing bed rest Hematopoetic system Baseline, after 10, 21 days of bed rest, 1, 28 days after finishing bed rest Blood cell count, reticulocytes, Haptoglobin, Bilirubin, Ferritin, EPO, Thrombopoietin, Urinary Urobilinogen and Fecal Urobilinogen (markers of blood cell degradation)
Fat accumulation in bone marrow Baseline, after 10, 21 days of bed rest, 3, 28 days after finishing bed rest Achilles tendon structure Baseline, after 21 days of bed rest, 2, 28 days after finishing bed rest Headache - frequency and quality Baseline, daily during 21 days of bed rest Muscle volume Baseline, after 20, 21 days of bed rest, 3 days after finishing bed rest Free water and fat content in muscle Baseline, after 20, 21 days of bed rest, 3 days after finishing bed rest Orthostatic tolerance Baseline, after 21 days of bed rest Orthostatic tolerance will be assessed by Head up tilt test. The following parameters are assessed to measure orthostatic tolerance: beat-to-beat heart rate \[bpm\], beat-to-beat blood pressure \[bpm\] time to presyncope \[min, s\]
Trial Locations
- Locations (1)
DLR German Aerospace Center
🇩🇪Cologne, Germany