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Cited by 352Spaceflight effects on biologyMuscle Physiology and DisordersCardiovascular and exercise physiology

Lower limb skeletal muscle function after 6 wk of bed rest

Berg, H. E., Larsson, L., Tesch, P. A.·1997·Journal of Applied Physiology
DOI 10.1152/jappl.1997.82.1.182
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Abstract

Force, electromyographic (EMG) activity, muscle mass, and fiber characteristics were studied in seven healthy men before and after 6 wk of bed rest. Maximum voluntary isometric and concentric knee extensor torque decreased (P < 0.05) uniformly across angular velocities by 25-30% after bed rest. Maximum quadricep rectified EMG decreased by 19 +/- 23%, whereas submaximum (100-Nm isometric action) EMG increased by 44 +/- 28%. Knee extensor muscle cross-sectional area (CSA), assessed by using magnetic resonance imaging, decreased by 14 +/- 4%. Maximum torque per knee extensor CSA decreased by 13 +/- 9%. Vastus lateralis fiber CSA decreased 18 +/- 14%. Neither type I, IIA, and IIB fiber percentages nor their relative proportions of myosin heavy chain (MHC) isoforms were altered after bed rest. Because the decline in strength could not be entirely accounted for by using decreased muscle CSA, it is suggested that the strength loss is also due to factors resulting in decreased neural input to muscle and/or reduced specific tension of muscle, as evidenced by decreased torque/EMG ratio. Additionally, it is concluded that muscle unloading in humans does not induce important changes in fiber type or MHC composition or in vivo muscle contractile properties.

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Crossref · 10.1152/jappl.1997.82.1.182

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  • Numerically established degeneration rates for the knee extensors differed by 5% to 80% dependent on the duration of disuse.

    “Numerically established degeneration rates for the knee extensors differed by 5% to 80% dependent on the duration of disuse (6, 18, 21–23).”

    From Nonuniform loss of muscle strength and atrophy during bed rest: a systematic review (2021) · cites this paper as [23]

  • The discrepancy between the loss of muscle quantity and function after bed rest must be further explained by a decrease in muscle quality, tendon alterations, neural factors, muscle architecture change, reduced neural drive, alterations in tendon mechanical properties, muscle fiber atrophy and force reduction, fiber phenotype shift, reduction in myofibrillar content, impaired calcium release, and,

    “The discrepancy between the loss of muscle quantity and function after bed rest must be further explained by a decrease in “muscle quality,” tendon alterations, and neural factors, muscle architecture change (79), reduced neural drive (23, 60, 80–82), alterations in tendon mechanical properties (83), muscle fiber atrophy and force reduction (72, 84–87), fiber phenotype shift toward fast twitch”

    From Nonuniform loss of muscle strength and atrophy during bed rest: a systematic review (2021) · cites this paper as [23]

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Authors
Berg, H. E., Larsson, L., & Tesch, P. A.
Affiliations
  • Karolinska Institutet (SE)
  • Karolinska University Hospital (SE)
ORCID
Venue
Journal of Applied Physiology
Publisher
American Physiological Society
Published
1997-01-01
Volume
82
Issue
1
Pages
182-188
ISSN
  • 0161-7567 (ISSN-L)
  • 8750-7587
  • 1522-1601
DOI
10.1152/jappl.1997.82.1.182
OpenAlex
W2171508974
Cited by
352
References
1
Citations by year
2026: 6 · 2025: 9 · 2024: 6 · 2023: 7 · 2022: 9 · 2021: 12 · 2020: 25 · 2019: 11 · 2018: 18 · 2017: 13 · 2016: 13 · 2015: 14 · 2014: 11 · 2013: 12 · 2012: 11
FWCI
4.98
Type
journal article
Language
en
Open access
closed
Locations
  • Journal of Applied Physiology (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Physiology › Spaceflight effects on biology
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
  • Health Sciences › Medicine › Complementary and alternative medicine › Cardiovascular and exercise physiology
Keywords
bed rest, disuse atrophy, knee extension torque, muscle cross-sectional area, myosin heavy chain isoforms, muscle fiber composition, muscle unloading, muscle strength decline
MeSH terms
Adult, Humans, Leg, Male, Muscle Contraction, Muscle, Skeletal, Muscle Fibers, Skeletal, Myosin Heavy Chains

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