Cited by 197Muscle Physiology and DisordersBone health and osteoporosis researchSpaceflight effects on biology

The DOI matches its Crossref record; 205 of the 217 references it cites were found in a registry or an index; none of the 204 sources its claims cite is checked for support yet.

Interactions between Muscle and Bone—Where Physics Meets Biology

Open access

Abstract

Muscle and bone interact via physical forces and secreted osteokines and myokines. Physical forces are generated through gravity, locomotion, exercise, and external devices. Cells sense mechanical strain via adhesion molecules and translate it into biochemical responses, modulating the basic mechanisms of cellular biology such as lineage commitment, tissue formation, and maturation. This may result in the initiation of bone formation, muscle hypertrophy, and the enhanced production of extracellular matrix constituents, adhesion molecules, and cytoskeletal elements. Bone and muscle mass, resistance to strain, and the stiffness of matrix, cells, and tissues are enhanced, influencing fracture resistance and muscle power. This propagates a dynamic and continuous reciprocity of physicochemical interaction. Secreted growth and differentiation factors are important effectors of mutual interaction. The acute effects of exercise induce the secretion of exosomes with cargo molecules that are capable of mediating the endocrine effects between muscle, bone, and the organism. Long-term changes induce adaptations of the respective tissue secretome that maintain adequate homeostatic conditions. Lessons from unloading, microgravity, and disuse teach us that gratuitous tissue is removed or reorganized while immobility and inflammation trigger muscle and bone marrow fatty infiltration and propagate degenerative diseases such as sarcopenia and osteoporosis. Ongoing research will certainly find new therapeutic targets for prevention and treatment.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

This review synthesizes how muscle and bone communicate through mechanical forces and secreted factors, integrating mechanobiology with endocrine/paracrine signaling. It argues that loading maintains musculoskeletal homeostasis while unloading and chronic inflammation drive fatty infiltration and degenerative diseases such as sarcopenia and osteoporosis.

Key findings

  • Mechanical impacts ranging from 0.1 to 100 kPa are sensed by adhesion molecules, ion channels, the primary cilium, and other mechanotransduction machinery, leading to bone formation, muscle hypertrophy, and enhanced ECM/cytoskeletal stiffness, fracture resistance, and muscle power.
  • Muscle and bone act as endocrine organs via myokines/osteokines and extracellular vesicles; exosomes are 50–150 nm and microvesicles 50–1000 nm (up to 10 µm), carrying miRNA, proteins, and organelles that may mediate exercise-induced cross-talk.
  • Unloading causes rapid loss: a meta-analysis of 75 simulated microgravity studies found moderate muscle changes within 7–14 days and large effects on muscle force, mass, and peak power after 35 days; 90-day 6° head-down tilt bed rest decreased muscle fiber cross-sectional area by 26%, with increased SOST and myostatin that was reversible upon reloading.
  • Chronic inflammation and disuse promote muscle fatty infiltration and bone marrow adipose expansion; in the EFFECT study of 40 female acute hip fracture patients and 55 controls, soft tissue parameters discriminated hip fractures as well as trabecular BMD plus cortical thickness.

Methods

  • Narrative review; no primary experimental data are reported. It synthesizes mechanistic, developmental, clinical, imaging, and spaceflight/bed-rest literature.
  • Cites specific studies and meta-analyses, including 75 simulated microgravity studies, a 90-day bed-rest study, the EFFECT cross-sectional study of 40 female hip fracture patients and 55 controls, and imaging methods such as DXA, BIA, CT, MRI/Dixon, and MRS.
  • Main analysis is conceptual integration of mechanotransduction, secretome/extracellular vesicle biology, immune and endothelial interactions, epigenetics, and disease mechanisms.

Limitations

  • The paper states that more research is needed to dissect molecular events, define the borders between beneficial and harmful mechanical stimuli, and understand exercise resistance in disease; it also says it cannot provide an in-depth review of any pathology.
  • Evident from the text: as a narrative review, no systematic search strategy or risk-of-bias assessment is described, and conclusions rely on selected cited literature rather than new data.
  • Evident from the text: many mechanistic claims derive from mouse or in vitro studies and are not fully validated in humans; imaging lacks guidelines for which parameters to quantify, and direct comparison of CT muscle density with MRI Dixon fat fraction has not been published.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.3390/biom10030432

Cites

205 of 205 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Figures

Figure 1 Schematic overview of the interaction between muscle and bone in physiology and pathology, addressing also the most important effectors of interaction. The green color represents the physiological interactions indicating that muscle hypertrophy and high bone mass have interdependent relationships, while the red color shows similarly strong mutual interaction between the loss of bone and muscle due to the intrinsic pathology in degenerative disease such as osteoporosis and sarcopenia, but also lifestyle, disuse, and underlying metabolic diseases such as chronic inflammatory conditions and diabetes mellitus.
Figure 1 Schematic overview of the interaction between muscle and bone in physiology and pathology, addressing also the most important effectors of interaction. The green color represents the physiological interactions indicating that muscle hypertrophy and high bone mass have interdependent relationships, while the red color shows similarly strong mutual interaction between the loss of bone and muscle due to the intrinsic pathology in degenerative disease such as osteoporosis and sarcopenia, but also lifestyle, disuse, and underlying metabolic diseases such as chronic inflammatory conditions and diabetes mellitus.CC BY · PubMed Central
Figure 2 Mechanisms of mechanotransduction. Graphical summary of the current knowledge on the transduction of mechanical signals into a cellular response. A) Mechanical strain applied to the cell and (the resulting) fluid flow activate receptors and channels and their downstream signaling cascades. In a tissue context, strain is transmitted between cells via a series of adhesion molecules such as integrins, cadherins, and tight junctions. Transcription factors become nucleotropic and address DNA regulatory elements such as repressors, enhancers, and their specific DNA response elements. Adaptive transcription and translation are initiated and lead to changes in transcriptome, proteome, and especially the secretome to communicate with neighbors and distant tissues. The expression and secretion of extracellular matrix proteins as parts of the secretome are upregulated. As a consequence, the incoming forces and the resistive response to external forces are enhanced, and a new homeostasis situation is produced. Similarly, the production of proteins of the cytoskeleton is enhanced, the cytoskeleton is also becoming stiffer, and the contractile proteins generate even more active forces. B) Fluid flow is sensed by the primary cilium. The relevant structural features of a primary cilium are schematically depicted on the right side, while the signaling cascades and tools for mechanotransduction are depicted on the left side. Deflection of the cilium generates signaling [43,44]. Intraflagellar transport is a means of active transport of signaling peptides to and from the cell body. C) The constitutive secretory pathway and the regulated secretory pathway are schematically depicted. While the latter has not been demonstrated in muscle or bone, it is characteristic for truly endocrine cells and requires complex sorting and the intravesicular storage of preformed proteins that are extruded upon endocrine signals. The constitutive pathway requires characteristic secretory peptide sequences to be continuously released into the extracellular environment and subsequently the circulation. The release of vesicles upon exercise-related calcium flux into the cell has been demonstrated to be a candidate mechanism for the release of proteins and miRNAs. Abbreviations: RTK: receptor tyrosine kinase; GPCR: G-protein coupled receptor; ATP: adenosine triphosphate; cAMP: cyclic adenosine-monophosphate; ECM: extracellular matrix; AKAPs: A-kinase anchoring proteins; PDEs: phosphodiesterases; P2X7R: purinergic receptor P2X, ligand-gated ion channel; TGN: trans-Golgi-network; This figures was created using inspiring information and cartoons from [6,9,40,44,45,46,47,48,49,50,51].
Figure 2 Mechanisms of mechanotransduction. Graphical summary of the current knowledge on the transduction of mechanical signals into a cellular response. A) Mechanical strain applied to the cell and (the resulting) fluid flow activate receptors and channels and their downstream signaling cascades. In a tissue context, strain is transmitted between cells via a series of adhesion molecules such as integrins, cadherins, and tight junctions. Transcription factors become nucleotropic and address DNA regulatory elements such as repressors, enhancers, and their specific DNA response elements. Adaptive transcription and translation are initiated and lead to changes in transcriptome, proteome, and especially the secretome to communicate with neighbors and distant tissues. The expression and secretion of extracellular matrix proteins as parts of the secretome are upregulated. As a consequence, the incoming forces and the resistive response to external forces are enhanced, and a new homeostasis situation is produced. Similarly, the production of proteins of the cytoskeleton is enhanced, the cytoskeleton is also becoming stiffer, and the contractile proteins generate even more active forces. B) Fluid flow is sensed by the primary cilium. The relevant structural features of a primary cilium are schematically depicted on the right side, while the signaling cascades and tools for mechanotransduction are depicted on the left side. Deflection of the cilium generates signaling [43,44]. Intraflagellar transport is a means of active transport of signaling peptides to and from the cell body. C) The constitutive secretory pathway and the regulated secretory pathway are schematically depicted. While the latter has not been demonstrated in muscle or bone, it is characteristic for truly endocrine cells and requires complex sorting and the intravesicular storage of preformed proteins that are extruded upon endocrine signals. The constitutive pathway requires characteristic secretory peptide sequences to be continuously released into the extracellular environment and subsequently the circulation. The release of vesicles upon exercise-related calcium flux into the cell has been demonstrated to be a candidate mechanism for the release of proteins and miRNAs. Abbreviations: RTK: receptor tyrosine kinase; GPCR: G-protein coupled receptor; ATP: adenosine triphosphate; cAMP: cyclic adenosine-monophosphate; ECM: extracellular matrix; AKAPs: A-kinase anchoring proteins; PDEs: phosphodiesterases; P2X7R: purinergic receptor P2X, ligand-gated ion channel; TGN: trans-Golgi-network; This figures was created using inspiring information and cartoons from [6,9,40,44,45,46,47,48,49,50,51].CC BY · PubMed Central
Figure 3 Magnetic resonance imaging (MRI)-based muscle imaging. Weighted image of young healthy (top left) and elderly sarcopenic male (top right). Water fraction (bottom left) and fat fraction (bottom right) images of subject shown in top right.
Figure 3 Magnetic resonance imaging (MRI)-based muscle imaging. Weighted image of young healthy (top left) and elderly sarcopenic male (top right). Water fraction (bottom left) and fat fraction (bottom right) images of subject shown in top right.CC BY · PubMed Central
Figure 4 Segmentation of MRI (magnetic resonance imaging) images. left: T1 image used for the segmentation of the fascia lata (red) separating the subcutaneous adipose tissue from the group of muscles and IMAT; center: Dixon fat fraction (FF) image with segmented: muscles (black) and IMAT (yellow and red), smaller agglomerations of extramyocellular lipids (EMCL) are shown in red; right: remaining muscle tissue for which FF is determined (Images from University of Erlangen).
Figure 4 Segmentation of MRI (magnetic resonance imaging) images. left: T1 image used for the segmentation of the fascia lata (red) separating the subcutaneous adipose tissue from the group of muscles and IMAT; center: Dixon fat fraction (FF) image with segmented: muscles (black) and IMAT (yellow and red), smaller agglomerations of extramyocellular lipids (EMCL) are shown in red; right: remaining muscle tissue for which FF is determined (Images from University of Erlangen).CC BY · PubMed Central

Verification

Claims the paper makes

102 Not checked yet · 24 Own interpretation · 19 No basis given

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  • It may state two separate claims as one. 59
  • Probably not a substantial claim. 15
  • The quote only partly states this claim. 2
70 of 70
  • The paper relies on this without support.

    Muscle and bone are derived from common precursors during development.

    “Muscle and bone are derived from common precursors during development, indicating a close relationship and interaction.”
  • The paper relies on this without support.

    There are currently no guidelines by which imaging parameter(s) should be quantified to address a given muscle composition question.

    “Currently, there are no guidelines by which imaging parameter(s) should be quantified to address a given muscle composition question.”
  • The paper relies on this without support.

    Comparative studies on imaging parameters for muscle composition are still missing.

    “Comparative studies are still missing.”
  • The paper relies on this without support.

    A direct comparison of CT muscle density with MRI Dixon FF results has not been published.

    “Interestingly, to the best of our knowledge, a direct comparison of CT muscle density with MRI Dixon FF results has not been published so far.”
  • The paper relies on this without support.

    The borders to pathology, which stimulus hurts cells, and which one stimulates adaptive remodeling are not yet exactly known.

    “We are beginning to understand the mechanisms of regulation, but we do not yet exactly know where the borders to pathology begin, which stimulus hurts cells, and which one stimulates adaptive remodeling.”
5 of 5

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Metadata

Authors
Herrmann, M., Engelke, K., Ebert, R., Müller-Deubert, S., Rudert, M., Ziouti, F., Jundt, F., Felsenberg, D., & Jakob, F.
Affiliations
  • University of Würzburg (DE)
  • Friedrich-Alexander-Universität Erlangen-Nürnberg (DE)
  • Universitätsklinikum Würzburg (DE)
  • Privatpraxis für Muskel- und Knochenkrankheiten, 12163 Berlin Germany
Corresponding author
Jakob, Franz
Venue
Biomolecules
Publisher
MDPI AG
Published
2020-03-10
Volume
10
Issue
3
Pages
432
ISSN
2218-273X (ISSN-L)
OpenAlex
W3010713274
Cited by
197
References
217
Citations by year
2026: 23 · 2025: 41 · 2024: 43 · 2023: 32 · 2022: 33 · 2021: 17 · 2020: 6
FWCI
2.11
Type
journal article
Language
en
Open access
Locations
  • Biomolecules (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • Online Publication Service of Würzburg University (Würzburg University) (submittedVersion, cc-by)
  • OPUS Repository (Kooperativer Bibliotheksverbund Berlin-Brandenburg) (submittedVersion, cc-by)
Funders
  • Deutsche Forschungsgemeinschaft (TRR 225, JU426/5-1, 326998133, 01EC1402C, D-361)
  • Bundesministerium für Bildung und Forschung (326998133-TRR 225, 01EC1402C, 326998133)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
  • Health Sciences › Medicine › Orthopedics and Sports Medicine › Bone health and osteoporosis research
  • Health Sciences › Medicine › Physiology (medical) › Spaceflight effects on biology
Keywords
muscle-bone interaction, mechanotransduction, osteokines, myokines, exosomes, extracellular matrix, muscle hypertrophy, bone formation, physical activity, microgravity, disuse, sarcopenia, osteoporosis, bone marrow adiposity, tissue stiffness
MeSH terms
Bone and Bones, Extracellular Matrix, Humans, Osteoporosis, Exercise, Muscle, Skeletal, Mechanotransduction, Cellular, Sarcopenia

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