Skeletal muscle unweighting: spaceflight and ground-based models
Open accessAbstract
Long-term manned spaceflight requires that flight crews be exposed to extended periods of unweighting of antigravity skeletal muscles. This exposure will result in adaptations in these muscles that have the potential to debilitate crew members on return to increased gravity environments. Therefore, the development of countermeasures to prevent these unwanted adaptations is an important requirement. The limited access to microgravity environments for the purpose of studying muscle adaptation and evaluating countermeasure programs has necessitated the use of ground-based models to conduct both basic and applied muscle physiology research. In this review, the published results from ground-based models of muscle unweighting are presented and compared with the results from related spaceflight research. The models of skeletal muscle unweighting with a sufficient body of literature included bed rest, cast immobilization, and unilateral lower limb suspension. Comparisons of changes in muscle strength and size between these models in the context of the limited results available from spaceflight suggest that each model may be useful for the investigation of certain aspects of the skeletal muscle unweighting that occur in microgravity.
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Skeletal muscle size and function continue to decline with the length of exposure until an asymptotic saturation is reached.
“Studies in adults documented that skeletal muscle size and function are already reduced after a few days of bed rest (12) and continue to decline with the length of exposure (13) until an asymptotic saturation is reached.”
From Nonuniform loss of muscle strength and atrophy during bed rest: a systematic review (2021) · cites this paper as [13]
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BackgroundInfluentialHuman fiber size and enzymatic properties after 5 and 11 days of spaceflight
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Gravity, Microgravity and Artificial Gravity: Physiological Effects, Implementation and Applications
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- Authors
- Adams, G. R., Caiozzo, V. J., & Baldwin, K. M.
- Affiliations
- University of California, Irvine (US)
- Venue
- Journal of Applied Physiology
- Publisher
- American Physiological Society
- Published
- 2003-12
- Volume
- 95
- Issue
- 6
- Pages
- 2185-2201
- ISSN
- 0161-7567 (ISSN-L)
- 8750-7587
- 1522-1601
- OpenAlex
- W2080869774
- Cited by
- 401
- References
- 3
- Citations by year
- 2026: 10 · 2025: 15 · 2024: 14 · 2023: 16 · 2022: 15 · 2021: 19 · 2020: 10 · 2019: 18 · 2018: 21 · 2017: 14 · 2016: 33 · 2015: 18 · 2014: 20 · 2013: 17 · 2012: 16
- FWCI
- 1.97
- Type
- journal article
- Language
- en
- Open access
- green
- escholarship.org
- Licence
- cc-by
- Locations
- Journal of Applied Physiology (publishedVersion)
- PubMed (publishedVersion)
- eScholarship (California Digital Library) (submittedVersion, cc-by)
- Funders
- National Space Biomedical Research Institute (NCC 9‐58)
- National Institutes of Health (5r01ar046856-05, 5r01ar045594-05)
- National Institute of Arthritis and Musculoskeletal and Skin Diseases (AR-45594, AR-46856)
- Topics
- Health Sciences › Medicine › Physiology › Spaceflight effects on biology
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
- Physical Sciences › Engineering › Aerospace Engineering › Space Exploration and Technology
- Keywords
- muscle atrophy, microgravity, spaceflight, countermeasures, bed rest, cast immobilization, muscle strength, muscle size, muscle adaptation
- MeSH terms
- Animals, Bed Rest, Humans, Models, Biological, Space Flight, Weightlessness, Databases, Factual, Weightlessness Simulation, Muscle, Skeletal, Muscle Fibers, Skeletal
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