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The effect of bed rest, unilateral limb immobilization and head-down tilt on muscle protein synthesis: a systematic review and meta-analysis

The effect of bed rest, unilateral limb immobilization and head-down tilt on muscle protein synthesis: a systematic review and meta-analysis
The effect of bed rest, unilateral limb immobilization and head-down tilt on muscle protein synthesis: a systematic review and meta-analysis

Muscle disuse leads to muscle atrophy and a decrease in muscle function that is primarily driven by reduced muscle protein synthesis (MPS). The aim of this systematic review and meta-analysis was to examine the effect of different models of muscle disuse on rates of MPS. A literature search was conducted in PubMed, Web of Science, Scopus and Cochrane Library. Eligible randomized and non-randomized controlled trials compared the effect of bed rest (BR), unilateral lower limb immobilization (ULLI), and 6° head-down tilt (HDT) on pre-post muscle disuse changes in MPS in adults. Using the random and fixed effects inverse-variance model, we calculated the mean difference (MD) in the effect of BR on mixed MPS and ULLI on myofibrillar MPS (MyoPS) (both expressed as fractional synthetic rate,%/h). The effect of HDT on MPS was examined through a narrative synthesis of data. A total of 16 studies were included in the systematic review and 13 in the meta-analysis. A significant reduction in mixed MPS was observed after BR (k = 4; MD: -0.017%/h, 95% CI: -0.023 to -0.011, I 2 = 24%, P < 0.01) and a significant reduction in MyoPS was observed after ULLI (k = 9; MD: -0.015%/h, 95% CI: -0.021 to -0.008, I 2 = 94%, P < 0.01). HDT led to reductions in both mixed MPS and MyoPS. A comparable reduction in mixed MPS and MyoPS was observed between different models of muscle disuse.

fractional synthetic rate, muscle disuse, physical inactivity, skeletal muscle
0958-0670
Prokopidis, Konstantinos
31f1f079-d93c-4ecd-9de6-df7759180fd8
Morgan, Paul T.
d01a26fc-a263-4936-af99-7a677a5952b1
Deane, Colleen S.
3320532e-f411-4ea8-9a14-4a9f248da898
Witard, Oliver C.
9acdc941-f6d8-4eff-9fcd-e6a00972d11a
Church, David D.
f39d1a56-4c26-426a-a1ba-0e87701a9195
Prokopidis, Konstantinos
31f1f079-d93c-4ecd-9de6-df7759180fd8
Morgan, Paul T.
d01a26fc-a263-4936-af99-7a677a5952b1
Deane, Colleen S.
3320532e-f411-4ea8-9a14-4a9f248da898
Witard, Oliver C.
9acdc941-f6d8-4eff-9fcd-e6a00972d11a
Church, David D.
f39d1a56-4c26-426a-a1ba-0e87701a9195

Prokopidis, Konstantinos, Morgan, Paul T., Deane, Colleen S., Witard, Oliver C. and Church, David D. (2025) The effect of bed rest, unilateral limb immobilization and head-down tilt on muscle protein synthesis: a systematic review and meta-analysis. Experimental Physiology. (doi:10.1113/EP092474).

Record type: Review

Abstract

Muscle disuse leads to muscle atrophy and a decrease in muscle function that is primarily driven by reduced muscle protein synthesis (MPS). The aim of this systematic review and meta-analysis was to examine the effect of different models of muscle disuse on rates of MPS. A literature search was conducted in PubMed, Web of Science, Scopus and Cochrane Library. Eligible randomized and non-randomized controlled trials compared the effect of bed rest (BR), unilateral lower limb immobilization (ULLI), and 6° head-down tilt (HDT) on pre-post muscle disuse changes in MPS in adults. Using the random and fixed effects inverse-variance model, we calculated the mean difference (MD) in the effect of BR on mixed MPS and ULLI on myofibrillar MPS (MyoPS) (both expressed as fractional synthetic rate,%/h). The effect of HDT on MPS was examined through a narrative synthesis of data. A total of 16 studies were included in the systematic review and 13 in the meta-analysis. A significant reduction in mixed MPS was observed after BR (k = 4; MD: -0.017%/h, 95% CI: -0.023 to -0.011, I 2 = 24%, P < 0.01) and a significant reduction in MyoPS was observed after ULLI (k = 9; MD: -0.015%/h, 95% CI: -0.021 to -0.008, I 2 = 94%, P < 0.01). HDT led to reductions in both mixed MPS and MyoPS. A comparable reduction in mixed MPS and MyoPS was observed between different models of muscle disuse.

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Accepted/In Press date: 7 October 2025
e-pub ahead of print date: 30 October 2025
Keywords: fractional synthetic rate, muscle disuse, physical inactivity, skeletal muscle

Identifiers

Local EPrints ID: 507256
URI: http://eprints.soton.ac.uk/id/eprint/507256
ISSN: 0958-0670
PURE UUID: eedb9897-469d-4426-bbee-0d758d22d4c1
ORCID for Colleen S. Deane: ORCID iD orcid.org/0000-0002-2281-6479

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Date deposited: 02 Dec 2025 18:05
Last modified: 03 Dec 2025 03:04

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Contributors

Author: Konstantinos Prokopidis
Author: Paul T. Morgan
Author: Colleen S. Deane ORCID iD
Author: Oliver C. Witard
Author: David D. Church

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