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Updated: May 13, 2026
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X-ray Diffraction of Intact Murine Skeletal Muscle as a Tool for Studying the Structural Basis of Muscle Disease
Published on: July 18, 2019
Muscle X-ray attenuation is not decreased during experimental bed rest
Jörn Rittweger1, Klaus Möller, Marie-Pierre Bareille
1Institute of Aerospace Medicine, German Aerospace Center, Cologne, Germany. joern.rittweger@dlr.de
Muscle & Nerve
|March 23, 2013
Summary
Muscle X-ray attenuation (MXA) did not decrease during 90-day bed rest (BR) in healthy men, contrary to our hypothesis. Exercise partially mitigated these changes, which reversed after BR.
Area of Science:
- Human physiology
- Muscle adaptation
- Imaging science
Background:
- Muscle X-ray attenuation (MXA) decreases with muscle atrophy from dystrophy, aging, and immobilization.
- Previous research indicated reduced MXA in various catabolic states.
Purpose of the Study:
- To investigate the effect of prolonged bed rest (BR) on muscle X-ray attenuation (MXA) in healthy men.
- To test the hypothesis that MXA decreases during bed rest.
Main Methods:
- Twenty-five healthy men underwent 90 days of bed rest.
- Eight participants performed flywheel exercise 2-3 times weekly.
- Muscle cross-sectional area (CSA) and MXA were measured using computed tomography.
Main Results:
- Calf muscle CSA decreased by 26.6% in the control group during 89 days of BR.
- Calf MXA increased by 1.2 HU on day 28 and returned to baseline by day 89.
- Flywheel exercise mitigated these changes (P < 0.001).
- All observed changes reversed within 90 days post-BR.
Conclusions:
- The study contradicts the hypothesis of decreased MXA during bed rest.
- Potential explanations for increased MXA include increased intramuscular blood content, reduced interstitial fluid, and decreased intramuscular lipids.
- These findings highlight complex muscle adaptations during unloading.
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