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Between-Subject and Within-Subject Variation of Muscle Atrophy and Bone Loss in Response to Experimental Bed Rest

Böcker, Jonas and Schmitz, Marie-Therese and Mittag, Uwe and Jordan, Jens and Rittweger, Jörn (2022) Between-Subject and Within-Subject Variation of Muscle Atrophy and Bone Loss in Response to Experimental Bed Rest. Frontiers in Physiology, 12, p. 743876. Frontiers Media S.A. doi: 10.3389/fphys.2021.743876. ISSN 1664-042X.

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Official URL: https://www.frontiersin.org/articles/10.3389/fphys.2021.743876/full


To improve quantification of individual responses to bed rest interventions, we analyzed peripheral quantitative computer tomography (pQCT) datasets of the lower leg of 76 participants, who took part in eight different bed rest studies. A newly developed statistical approach differentiated measurement uncertainty UMeas from betweensubject-variation (BSV) and within-subject variation (WSV). The results showed that UMeas decreased 59.3–80% over the two decades of bed rest studies (p < 0.01), and that it was higher for muscles than for bones. The reduction of UMeas could be explained by improved measurement procedures as well as a higher standardization. The vast majority (89.6%) of the individual responses pci exceeded the 95% confidence interval defined by UMeas, indicating significant and substantial BSV, which was greater for bones than for muscles, especially at the epiphyseal measurement sites. Non-significant to small positive inter-site correlations between bone sites, but very large positive inter-site correlation between muscle sites suggests that substantial WSV exists in the tibia bone, but much less so in the calf musculature. Furthermore, endocortical circumference, an indicator of the individual’s bone geometry could partly explain WSV and BSV. These results demonstrate the existence of substantial BSV bone, and that it is partly driven by WSV, and likely also by physical activity and dietary habits prior to bed rest. In addition, genetic and epigenetic variation could potentially explain BSV, but not WSV. As to the latter, differences of bone characteristics and the bone resorption process could offer an explanation for its existence. The study has also demonstrated the importance of duplicate baseline measurements. Finally, we provide here a rationale for worst case scenarios with partly effective countermeasures in long-term space missions.

Item URL in elib:https://elib.dlr.de/185499/
Document Type:Article
Title:Between-Subject and Within-Subject Variation of Muscle Atrophy and Bone Loss in Response to Experimental Bed Rest
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Böcker, JonasUNSPECIFIEDhttps://orcid.org/0000-0002-2388-0384UNSPECIFIED
Mittag, UweUNSPECIFIEDhttps://orcid.org/0000-0002-8580-3085UNSPECIFIED
Jordan, JensUNSPECIFIEDhttps://orcid.org/0000-0003-4518-0706UNSPECIFIED
Rittweger, JörnUNSPECIFIEDhttps://orcid.org/0000-0002-2223-8963UNSPECIFIED
Date:22 February 2022
Journal or Publication Title:Frontiers in Physiology
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
Page Range:p. 743876
Publisher:Frontiers Media S.A
Keywords:between-subject variation, within-subject variation, measurement uncertainty, bed rest, muscle atrophy, bone loss
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Research under Space Conditions
DLR - Research theme (Project):R - Bone metabolism and structural adaptation, R - Muscle Mechanics and Metabolism
Location: Köln-Porz
Institutes and Institutions:Institute of Aerospace Medicine > Muscle and Bone Metabolism
Institute of Aerospace Medicine > Leitungsbereich ME
Deposited By: Böcker, Jonas
Deposited On:08 Apr 2022 12:31
Last Modified:09 May 2023 11:40

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