Increased mitochondrial surface area and cristae density in the skeletal muscle of strength athletes

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  • Javier Botella
  • Camilla T. Schytz
  • Thomas F. Pehrson
  • Rune Hokken
  • Simon Laugesen
  • Per Aagaard
  • Suetta, Charlotte
  • Britt Christensen
  • Niels Ørtenblad
  • Joachim Nielsen
Mitochondria are the cellular organelles responsible for resynthesising the majority of ATP. In skeletal muscle, there is an increased ATP turnover during resistance exercise to sustain the energetic demands of muscle contraction. Despite this, little is known regarding the mitochondrial characteristics of chronically strength-trained individuals and any potential pathways regulating the strength-specific mitochondrial remodelling. Here, we investigated the mitochondrial structural characteristics in skeletal muscle of strength athletes and age-matched untrained controls. The mitochondrial pool in strength athletes was characterised by increased mitochondrial cristae density, decreased mitochondrial size, and increased surface-to-volume ratio, despite similar mitochondrial volume density. We also provide a fibre-type and compartment-specific assessment of mitochondria morphology in human skeletal muscle, which reveals across groups a compartment-specific influence on mitochondrial morphology that is largely independent of fibre type. Furthermore, we show that resistance exercise leads to signs of mild mitochondrial stress, without an increase in the number of damaged mitochondria. Using publicly available transcriptomic data we show that acute resistance exercise increases the expression of markers of mitochondrial biogenesis, fission and mitochondrial unfolded protein responses (UPRmt). Further, we observed an enrichment of the UPRmt in the basal transcriptome of strength-trained individuals. Together, these findings show that strength athletes possess a unique mitochondrial remodelling, which minimises the space required for mitochondria. We propose that the concurrent activation of markers of mitochondrial biogenesis and mitochondrial remodelling pathways (fission and UPRmt) with resistance exercise may be partially responsible for the observed mitochondrial phenotype of strength athletes.
OriginalsprogEngelsk
TidsskriftJournal of Physiology
Vol/bind601
Udgave nummer14
Sider (fra-til)2899-2915
Antal sider17
ISSN0022-3751
DOI
StatusUdgivet - 2023

Bibliografisk note

Funding Information:
Javier Botella is supported by an Executive Dean Health Postdoctoral research fellowship from Deakin University. This work was supported by the Danish Council for Independent Research (DFF – 1333‐00144 to J.N.).

Funding Information:
Javier Botella is supported by an Executive Dean Health Postdoctoral research fellowship from Deakin University. This work was supported by the Danish Council for Independent Research (DFF – 1333-00144 to J.N.). We acknowledge the Core Facility for Integrated Microscopy, Faculty of Health and Medical Sciences, University of Copenhagen. Open access publishing facilitated by Deakin University, as part of the Wiley - Deakin University agreement via the Council of Australian University Librarians.

Publisher Copyright:
© 2023 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

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