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Muscle Mass During Space Exploration

This study has been completed.
National Space Biomedical Research Institute
Information provided by (Responsible Party):
The University of Texas Medical Branch, Galveston Identifier:
First received: August 28, 2009
Last updated: May 27, 2015
Last verified: May 2015

The investigators will test the following hypotheses:

  1. Bedrest will blunt the anabolic response to a mixed nutrient meal, facilitating a loss of muscle mass and functional capacity that is only partially restored during rehabilitation.
  2. Enriching daily meals with leucine will promote protein synthesis and maintain the anabolic response to mixed nutrient meal ingestion. This will preserve lean muscle mass and function during bedrest and facilitate the recovery of functional and metabolic capacity during rehabilitation.

Condition Intervention Phase
Muscle Loss Dietary Supplement: Leucine Phase 3

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double Blind (Participant, Investigator)
Primary Purpose: Basic Science
Official Title: An Integrated Low-Volume Nutritional Countermeasure to Maintain Muscle Mass and Function During Space Exploration

Resource links provided by NLM:

Further study details as provided by The University of Texas Medical Branch, Galveston:

Primary Outcome Measures:
  • Muscle protein synthesis [ Time Frame: 4 yrs ]

Enrollment: 40
Study Start Date: August 2009
Study Completion Date: April 2015
Primary Completion Date: April 2015 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Leucine Dietary Supplement: Leucine
3-4g Leucine added to daily meals
Placebo Comparator: Placebo Dietary Supplement: Leucine
Powered amino acid
Other Name: Alanine

Detailed Description:

Our long-term goal is to identify, prevent and remedy defects in the metabolic pathway that contribute to the loss of muscle mass and function during exposure to microgravity. Demographic data indicate that the average age of shuttle crew members has increased from 40.7 yrs in 1995 to 46.7 yrs in 2007 with an increasing number of astronauts over 50 yrs of age. We contend that the loss of muscle mass and function during spaceflight is facilitated by an age-associated, progressive impairment in the ability to mount an anabolic response to standard mixed nutrient meals. We propose that enriching daily meals with a low-volume leucine supplement will reduce the deleterious effects of microgravity on skeletal muscle and facilitate recovery during rehabilitation.

We will employ our established 14 day bed rest protocol to model the skeletal muscle unloading that occurs during microgravity. We will also examine recovery of muscle mass and functional capacity during a 7 day rehabilitation period. We will study 2 groups: CON (Bedrest/Recovery + Placebo; n=15), LEU (Bedrest/Recovery + Leucine; n=15). We will assess a) markers of translation initiation, b) muscle protein synthesis, c) muscle mass and body composition and d) strength and aerobic capacity.


Ages Eligible for Study:   45 Years to 60 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  1. Age between 45-60
  2. Ability to sign informed consent

Exclusion Criteria:

  1. Subjects with cardiac abnormalities considered exclusionary by the study physicians
  2. Subjects with uncontrolled metabolic disease
  3. A GFR <65 mL/min/1.73m2 or evidence of kidney disease or failure
  4. Subjects with vascular disease or risk factors of peripheral atherosclerosis
  5. Any history of hypo- or hyper-coagulation disorders. (e.g., Coumadin use or history of DVT or PE)
  6. Subjects with chronically elevated systolic pressure >150 or a diastolic blood pressure > 100
  7. Subjects with implanted electronic devices (e.g., pacemakers, electronic infusion pumps, stimulators)
  8. Subjects with recently (6 months) treated cancer other than basal cell carcinoma
  9. Any subject currently on a weight-loss diet or a body mass index > 30 kg/m2
  10. Inability to abstain from smoking for duration of study
  11. A history of > 20 pack per year smoking
  12. Any subject that is HIV-seropositive or has active hepatitis
  13. Recent anabolic or corticosteroids use (within 3 months)
  14. Subjects with hemoglobin or hematocrit lower than accepted lab values
  15. Agitation/aggression disorder
  16. History of stroke with motor disability
  17. A recent history (<12 months) of GI bleed
  18. Any other condition or event considered exclusionary by the PI and faculty physician
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Please refer to this study by its identifier: NCT00968344

United States, Texas
The University of Texas Medical Branch
Galveston, Texas, United States, 77555
Sponsors and Collaborators
The University of Texas Medical Branch, Galveston
National Space Biomedical Research Institute
Principal Investigator: Douglas Paddon-Jones, PhD The University of Texas Medical Branch at Galveston
  More Information

Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: The University of Texas Medical Branch, Galveston Identifier: NCT00968344     History of Changes
Other Study ID Numbers: 09-121
Study First Received: August 28, 2009
Last Updated: May 27, 2015 processed this record on July 26, 2017