Universität zu Köln

Boecker, Jonas, Schmitz, Marie-Therese ORCID: 0000-0003-1351-9381, Mittag, Uwe, Jordan, Jens and Rittweger, Joern (2022). Between-Subject and Within-Subject Variaton of Muscle Atrophy and Bone Loss in Response to Experimental Bed Rest. Front. Physiol., 12. LAUSANNE: FRONTIERS MEDIA SA. ISSN 1664-042X

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Abstract

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 U-Meas from between-subject-variation (BSV) and within-subject variation (WSV). The results showed that U-Meas 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 U-Meas could be explained by improved measurement procedures as well as a higher standardization. The vast majority (89.6%) of the individual responses pc(i) exceeded the 95% confidence interval defined by U-Meas, 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 Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Boecker, Jonas UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmitz, Marie-Therese UNSPECIFIED orcid.org/0000-0003-1351-9381 UNSPECIFIED Mittag, Uwe UNSPECIFIED UNSPECIFIED UNSPECIFIED Jordan, Jens UNSPECIFIED UNSPECIFIED UNSPECIFIED Rittweger, Joern UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-680878
DOI:	10.3389/fphys.2021.743876
Journal or Publication Title:	Front. Physiol.
Volume:	12
Date:	2022
Publisher:	FRONTIERS MEDIA SA
Place of Publication:	LAUSANNE
ISSN:	1664-042X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language MICROGRAVITY EXPOSURE; SPACE-FLIGHT; STRENGTH; DETERMINANT; VARIABILITY; PAMIDRONATE; EXERCISE; PROGRAM; SYSTEM; DISUSE Multiple languages Physiology Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/68087