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Completed

NCT Number: NCT01655979

Medium-term Bedrest Whey Protein (MEP)

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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Key information

Conditions

Countermeasure Evaluation

Age range

20 year–45 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

DLR German Aerospace Center

Cologne, 51147, Germany

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 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

Exclusion criteria

  • 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

Treatment and study plan

Whey Protein + Potassium bicarbonate

Dietary Supplement

0.6 mmol WP/kg body weight + 90 mmol KHCO3 during bed rest

Control

Other

Bed rest without dietary supplement

Primary outcomes

  1. Change in body composition

    Time frame: Baseline, after 21 days of bed rest

Secondary outcomes

  1. Plasma Volume

    Time frame: Baseline, after 21 days of bed rest

  2. Maximum volume of oxygen uptake

    Time frame: Baseline, after 21 days of bed rest

  3. Isometric torque

    Time frame: 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.

  4. Muscle fatigue

    Time frame: Baseline, after 21 days of bed rest

  5. Bone metabolism

    Time frame: Baseline, after 2,5,14,21 days of bed rest, 1, 5, 14, 28 days after finishing bed rest

  6. Bone mineral density + content

    Time frame: Baseline, after 21 days of bed rest

  7. Standing balance

    Time frame: Baseline, after 21 days of bed rest

  8. Locomotion

    Time frame: Baseline, after 21 days of bed rest

    Locomotion will be assessed by Dynamic Gait Index, specific parameters are: total Score and Subscore

  9. Body mass

    Time frame: Daily for a duration of 35 days

  10. 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

  11. Monitoring of Vitamin K status

    Time frame: Baseline, after 2,5,14,21 days of bed rest, 1, 5 days after finishing bed rest

  12. Fat metabolism

    Time frame: Baseline, after 21 days of bed rest

  13. Glucose metabolism

    Time frame: Baseline, after 21 days of bed rest, 4 days after finishing bed rest

  14. Nitrogen balance

    Time frame: Daily for a duration of 33 days

  15. Energy metabolism

    Time frame: Baseline, after 21 days of bed rest

  16. 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

  17. Muscle metabolism

    Time frame: Baseline, after 21 days of bed rest

  18. Acid base balance

    Time frame: Baseline, after 2, 14, 21 days of bed rest, 5 days after finishing bed rest

  19. Sympathetic activity during orthostatic stress

    Time frame: Baseline, after 21 days of bed rest

    Muscle sympathetic nerve activity is measured by MSNA recording by microneurography technique.

  20. Visual Orientation

    Time frame: 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.

  21. Plasma galanin and adrenomedullin responses during head up tilt test (orthostatic stress)

    Time frame: Baseline, after 21 days of bed rest

  22. Cartilage metabolism and -thickness

    Time frame: Baseline, after 2,3,5,7,14,21 days of bed rest, 5 days after finishing bed rest

  23. Hematopoetic system

    Time frame: 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)

  24. Fat accumulation in bone marrow

    Time frame: Baseline, after 10, 21 days of bed rest, 3, 28 days after finishing bed rest

  25. Achilles tendon structure

    Time frame: Baseline, after 21 days of bed rest, 2, 28 days after finishing bed rest

  26. Headache - frequency and quality

    Time frame: Baseline, daily during 21 days of bed rest

  27. Muscle volume

    Time frame: Baseline, after 20, 21 days of bed rest, 3 days after finishing bed rest

  28. Free water and fat content in muscle

    Time frame: Baseline, after 20, 21 days of bed rest, 3 days after finishing bed rest

  29. Orthostatic tolerance

    Time frame: 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]

Sponsors and collaborators

Lead sponsor

DLR German Aerospace Center

Other

Collaborators

  • Charite University, Berlin, Germany
  • European Space Agency
  • Institut Pluridisciplinaire Hubert Curien, Strasbourg, France
  • Leiden University Medical Center
  • Manchester Metropolitan University
  • Medical University of Graz
  • Radboud University Medical Center
  • University Hospital, Clermont-Ferrand
  • University Hospital, Lille
  • University of Cologne
  • University of Milan
  • University of Ottawa
  • University of Toronto
  • Université de Nice Sophia Antipolis

Registry information

Acronym: MEP

Important dates

Study start
2011
Primary completion
2012
First posted
Aug 2, 2012
Registry last updated
Aug 2, 2012

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.