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Abstract
Bed rest (BR) results in significant impairments in skeletal muscle metabolism. Mitochondrial metabolism is reportedly highly sensitive to disuse, with dysregulated fission-fusion events and impaired oxidative function previously reported. The effects of clinically relevant short-term BR (≤5 days) on mitochondrial protein expression are presently unclear, as are the effects of exercise prehabilitation as a potential counteractive intervention. The present study examined the effects of a 5-day period of BR and short-term resistance exercise prehabilitation (ST-REP) on mitochondrial-protein content. Ten older men (71 ± 4 years) underwent 5 days of BR, completing four sessions of high-volume unilateral resistance exercise prehabilitation over 7 days beforehand. Muscle biopsies were obtained from the vastus lateralis in the non-exercised control and exercised legs, both pre- and post-prehabilitation and pre- and post-BR, to determine changes in citrate synthase enzyme activity and the expression of key proteins in the mitochondrial electron transport chain and molecular regulators of fission-fusion dynamics, biosynthesis, and mitophagy. We observed no significant effect of either BR or ST-REP on citrate synthase protein content, enzyme activity, or ETC complex I-V protein content. Moreover, we observed no significant changes in markers of mitochondrial fission and fusion (p-DRP1 S616, p-DRP1 S637, p-DRP1 S616/S637 ratio, p-MFF S146, Mitofillin, OPA1, or MFN2 (p > 0.05 for all). Finally, we observed no differences in markers of biosynthesis (p-AMPK T172, p-ACC S79, PGC1a, TFAM) or mitophagy-related signaling (ULK-1, BNIP3/NIX, LC3B I/II) (p > 0.05 for all). In contrast to previous longer-term periods of musculoskeletal disuse (i.e., 7-14 days), a clinically relevant, 5-day period of BR resulted in no significant perturbation in muscle mitochondrial protein signaling in healthy older adults, with no effect of ST-REP in the week prior to BR. Accordingly, disuse-induced muscle atrophy may precede alterations in mitochondrial content.
Original language | English |
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Article number | e15345 |
Number of pages | 14 |
Journal | Physiological reports |
Volume | 10 |
Issue number | 13 |
DOIs | |
Publication status | Published - 3 Jul 2022 |
Bibliographical note
Funding Information:This work was supported by an award from the Biotechnology and Biological Sciences Research Council to L.B. (BB/N018214/1) and the NIHR Clinical Research Facility in University Hospitals Birmingham NHS Foundation Trust, Birmingham. R.N.M. is funded by the MRC‐Versus Arthritis, Centre for Musculoskeletal Ageing Research, Doctoral Training Partnership between the University of Birmingham and University of Nottingham.
Publisher Copyright:
© 2022 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.
Keywords
- ageing
- bed rest
- disuse
- mitochondria
- skeletal muscle
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Exercise 'prehabilitation': A novel intervention to protect against disuse-induced muscle atrophy and sarcopenia in the old
Breen, L. & Rushton, A.
Biotechnology & Biological Sciences Research Council
1/09/16 → 30/11/19
Project: Research Councils