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

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

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. KEY POINTS: Untrained individuals and strength athletes possess comparable skeletal muscle mitochondrial volume density. In contrast, strength athletes' mitochondria are characterised by increased cristae density, decreased size and increased surface-to-volume ratio. Type I fibres have an increased number of mitochondrial profiles with minor differences in the mitochondrial morphological characteristics compared with type II fibres. The mitochondrial morphology is distinct across the subcellular compartments in both groups, with subsarcolemmal mitochondria being bigger in size when compared with intermyofibrillar. Acute resistance exercise leads to signs of mild morphological mitochondrial stress accompanied by increased gene expression of markers of mitochondrial biogenesis, fission and mitochondrial unfolded protein response (UPRmt ).

Medienart:	E-Artikel

Erscheinungsjahr:	2023
Erschienen:	2023

Enthalten in:	Zur Gesamtaufnahme - volume:601
Enthalten in:	The Journal of physiology - 601(2023), 14 vom: 01. Juli, Seite 2899-2915

Sprache:	Englisch

Beteiligte Personen:	Botella, Javier [VerfasserIn] Schytz, Camilla T [VerfasserIn] Pehrson, Thomas F [VerfasserIn] Hokken, Rune [VerfasserIn] Laugesen, Simon [VerfasserIn] Aagaard, Per [VerfasserIn] Suetta, Charlotte [VerfasserIn] Christensen, Britt [VerfasserIn] Ørtenblad, Niels [VerfasserIn] Nielsen, Joachim [VerfasserIn]

Links:	Volltext

Themen:	8L70Q75FXE Adenosine Triphosphate Cristae density Journal Article Mitochondria Olympic weightlifting Resistance exercise Skeletal muscle Strength

Anmerkungen:	Date Completed 17.07.2023 Date Revised 16.11.2023 published: Print-Electronic Citation Status MEDLINE

doi:	10.1113/JP284394

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PPN (Katalog-ID):	NLM35546943X