An interventional study of Whey Protein + Potassium bicarbonate and Control in Countermeasure Evaluation, sponsored by DLR German Aerospace Center. Completed at 1 site in Germany. Open to male participants aged 20 Years to 45 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2012-08-02.
Sponsored by DLR German Aerospace Center · Not applicable, Interventional, and Treatment
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.
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Exclusion Criteria:
Dietary Supplement: Whey Protein + Potassium bicarbonate · Other: Control
Dietary Supplement: Whey Protein + Potassium bicarbonate · Other: Control
0.6 mmol WP/kg body weight + 90 mmol KHCO3 during bed rest
Bed rest without dietary supplement
Change in body composition
Time frame: Baseline, after 21 days of bed rest
Plasma Volume
Time frame: Baseline, after 21 days of bed rest
Maximum volume of oxygen uptake
Time frame: Baseline, after 21 days of bed rest
Isometric torque
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.
Time frame: Baseline, after 21 days of bed rest
Muscle fatigue
Time frame: Baseline, after 21 days of bed rest
Bone metabolism
Time frame: Baseline, after 2,5,14,21 days of bed rest, 1, 5, 14, 28 days after finishing bed rest
Bone mineral density + content
Time frame: Baseline, after 21 days of bed rest
Standing balance
Time frame: Baseline, after 21 days of bed rest
Locomotion
Locomotion will be assessed by Dynamic Gait Index, specific parameters are: total Score and Subscore
Time frame: Baseline, after 21 days of bed rest
Body mass
Time frame: Daily for a duration of 35 days
Intracranial pressure
Time frame: 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
Time frame: Baseline, after 2,5,14,21 days of bed rest, 1, 5 days after finishing bed rest
Fat metabolism
Time frame: Baseline, after 21 days of bed rest
Glucose metabolism
Time frame: Baseline, after 21 days of bed rest, 4 days after finishing bed rest
Nitrogen balance
Time frame: Daily for a duration of 33 days
Energy metabolism
Time frame: Baseline, after 21 days of bed rest
Glucocorticoid activity
Time frame: Baseline, after 2,3,7,8,12,13,16,17 days of bed rest, 2,3 days after finishing bed rest
Muscle metabolism
Time frame: Baseline, after 21 days of bed rest
Acid base balance
Time frame: Baseline, after 2, 14, 21 days of bed rest, 5 days after finishing bed rest
Sympathetic activity during orthostatic stress
Muscle sympathetic nerve activity is measured by MSNA recording by microneurography technique.
Time frame: Baseline, after 21 days of bed rest
Visual Orientation
Visual Orientation is assessed by 'Oriented Character Recognition Test' and Luminous Line Test. The main parameter is Score.
Time frame: Baseline, after 6,12,20 days of bed rest, 2,4 days after finishing bed rest
Plasma galanin and adrenomedullin responses during head up tilt test (orthostatic stress)
Time frame: Baseline, after 21 days of bed rest
Cartilage metabolism and -thickness
Time frame: Baseline, after 2,3,5,7,14,21 days of bed rest, 5 days after finishing bed rest
Hematopoetic system
Blood cell count, reticulocytes, Haptoglobin, Bilirubin, Ferritin, EPO, Thrombopoietin, Urinary Urobilinogen and Fecal Urobilinogen (markers of blood cell degradation)
Time frame: Baseline, after 10, 21 days of bed rest, 1, 28 days after finishing bed rest
Fat accumulation in bone marrow
Time frame: Baseline, after 10, 21 days of bed rest, 3, 28 days after finishing bed rest
Achilles tendon structure
Time frame: Baseline, after 21 days of bed rest, 2, 28 days after finishing bed rest
Headache - frequency and quality
Time frame: Baseline, daily during 21 days of bed rest
Muscle volume
Time frame: Baseline, after 20, 21 days of bed rest, 3 days after finishing bed rest
Free water and fat content in muscle
Time frame: Baseline, after 20, 21 days of bed rest, 3 days after finishing bed rest
Orthostatic tolerance
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 \[min, s\]
Time frame: Baseline, after 21 days of bed rest
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DLR German Aerospace Center