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Reposted by Joachim Nielsen

Matthew Alexander, PhD @mattmuscleguy.bsky.social · 1d

New #scisignal paper: Phosphorylation of RYR1 at Ser2902 decreases Ca2+ leak in skeletal muscle and susceptibility to malignant hyperthermia and heat stroke. #Myoblue tinyurl.com/bddss3j6

Phosphorylation of RYR1 at Ser2902 decreases Ca2+ leak in skeletal muscle and susceptibility to malignant hyperthermia and heat stroke

Reducing Ca2+ leak through mutant RYR1 prevents pathological heat production in skeletal muscle.

tinyurl.com

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Reposted by Joachim Nielsen

Aydin Lab @aydinlab.bsky.social · 8d

Excited to share that our paper on mitochondrial cardiolipin dynamics is published in @natcomms.nature.com today! We provide molecular explanations for unique aspects of mitochondrial morphology and the mechanisms underlying cardiolipin-related Barth Syndrome.
www.nature.com/articles/s41...

Cardiolipin dynamics promote membrane remodeling by mitochondrial OPA1 - Nature Communications

This study reveals how cardiolipin governs mitochondrial morphology by modulating the activity of human OPA1 and how its replacement by monolyso-cardiolipin, as observed in Barth syndrome, impacts mitochondrial membrane-shaping mechanisms.

www.nature.com

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Joachim Nielsen @joachimnielsen.bsky.social · 8d

The data show that eight weeks of HIIT training led to a 7% increase in mitochondrial cristae density, demonstrating cristae plasticity.
Importantly, this plasticity was also observed in patients with type 2 diabetes, highlighting its relevance for metabolic health.

Joachim Nielsen @joachimnielsen.bsky.social · 8d

This level of precision was necessary to detect training-induced changes in cristae density, as previous data suggested expected increases of <10%. Even in athletes, cristae density is only ~25% higher than in untrained individuals.

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Joachim Nielsen @joachimnielsen.bsky.social · 8d

In our previous studies, we used a cut-off of 8 profiles to achieve a coefficient of error of 0.10.
To improve precision, significantly more work (x5) was required, moving onto the flatter part of the curve where additional profiles yield marginal gains in accuracy.

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Joachim Nielsen @joachimnielsen.bsky.social · 8d

Martin and Amalie manually analysed ~11,000 mitochondrial profiles for cristae density using classical stereology: counting intersections with cristae and points with mitochondria.
Each biopsy typically included >100 profiles, with a minimum cut-off of 49 profiles to ensure a CE ≤ 0.05.

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Joachim Nielsen @joachimnielsen.bsky.social · 8d

Martin performed TEM imaging on 117 muscle biopsies (pre- and post-training), resulting in ~17,000 images.
These were analysed for mitochondrial and lipid droplet parameters, as published here: 🔗 10.1152/ajpcell.00470.2022 and 10.1113/JP284386

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Joachim Nielsen @joachimnielsen.bsky.social · 8d

At that time, we had biopsies before and after 10 weeks of aerobic training but found no effect of training on cristae density, raising questions about its plasticity.

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Joachim Nielsen @joachimnielsen.bsky.social · 8d

Until 2017, the prevailing consensus was that mitochondrial cristae density remained unchanged with training. However, in a cross-sectional study, we observed that endurance-trained athletes had a 25% higher cristae density compared to untrained individuals: 10.1113/JP273040

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Joachim Nielsen @joachimnielsen.bsky.social · 8d

Our new preprint!
Great effort by Martin de Almeida and Amalie Platz has led to the discovery that training increases mitochondrial cristae density.
www.biorxiv.org/cgi/content/...
Thanks to Niels Ørtenblad at SDU and Kurt Højlund and Maria Petersen at Steno Diabetes Center Odense.

🧵 Thread below…

Mitochondrial cristae density is increased following high-intensity interval training in patients with type 2 diabetes

Aims/hypothesis: Mitochondrial cristae architecture is a key determinant of oxidative capacity in skeletal muscle. While mitochondrial dysfunction is common in type 2 diabetes, it remains unclear whet...

www.biorxiv.org

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Sakamoto Lab @labsakamoto.bsky.social · 9d

Check out our latest preprint from the lab, spearheaded by researcher @itsmedipsikha.bsky.social , investigating the distinctive roles of regulatory gamma subunits of the AMPK protein complex in small molecule activator-stimulated skeletal muscle glucose uptake.
www.biorxiv.org/content/10.1...

Common and distinct roles of AMPKγ isoforms in small-molecule activator-stimulated glucose uptake in mouse skeletal muscle

Objective: Small-molecule activators targeting the allosteric drug and metabolite (ADaM) site of AMPK enhance insulin-independent glucose uptake in skeletal muscle and lower glucose in preclinical mod...

www.biorxiv.org

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Joachim Nielsen @joachimnielsen.bsky.social · 9d

www.biorxiv.org/content/10.1...

Electron tomography reveals mitochondrial network and cristae remodelling during cell differentiation in the human placenta

Mitochondria adapt their structure through fusion and fission, yet how their morphology and cristae architecture alter as cells differentiate remains unclear. The human placenta is an ideal model for ...

www.biorxiv.org

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Experimental Physiology @expphysiol.bsky.social · 12d

Does biological sex impact the rate of intrinsic mitochondrial respiration in the presence of creatine in human skeletal muscle? Emily J. Ferguson (@queensuresearch.bsky.social) et al. investigate!

📜 buff.ly/46B6lzL

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bioRxiv Physiology @biorxiv-physio.bsky.social · 18d

Mechanical Loading Induces the Longitudinal Growth of Muscle Fibers via an mTORC1-Independent Mechanism https://www.biorxiv.org/content/10.1101/2025.09.19.676647v1

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Joachim Nielsen @joachimnielsen.bsky.social · 29d

Divergent Changes in Peak Fat Oxidation and Fatmax Following 3-Day Dietary Interventions Are Related to Muscle Glycogen Availability in Men

by Tarry, Vestergaard, Petersen, Olsen, Ingersen, Connor, Pilegaard, Dela, Larsen, Shaw, and Helge

onlinelibrary.wiley.com/share/CDCGW2...

Divergent Changes in Peak Fat Oxidation and Fatmax Following 3‐Day Dietary Interventions Are Related to Muscle Glycogen Availability in Men

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onlinelibrary.wiley.com

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Nature Reviews Disease Primers @natrevdiseaseprimers.nature.com · Sep 6

Sarcopenia is accelerated loss of skeletal muscle mass and function commonly, but not exclusively, associated with advancing age. It is observed across many species including humans in whom it can lead to decline in physical function and mobility. https://www.nature.c...

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Reposted by Joachim Nielsen

Craig A. Goodman @craigagoodman1.bsky.social · Aug 30

Congrats to Steffen Raun, Lykke Sylow and Team for their new Redox Biology paper, "Skeletal muscle Rac1 mediates exercise training adaptations towards muscle glycogen resynthesis and protein synthesis", that included the CMR's Prof Paul Gregorevic
www.sciencedirect.com/science/arti...

Skeletal muscle Rac1 mediates exercise training adaptations towards muscle glycogen resynthesis and protein synthesis

Long-term exercise training elicits tremendous health benefits; however, the molecular understanding is incomplete and identifying therapeutic targets…

www.sciencedirect.com

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Michele Zanini @mzaniniphysiology.bsky.social · Aug 29

🚨 The last paper of my PhD is out in @MSSE

Regular Long Runs and Higher Training Volumes are Associated with Better Running Economy Durability in Performance Matched Well-Trained Male Runners

🙏🏻 Rich Blagrove & Jonathan Folland

Temporary free download.

🔗 journals.lww.com/acsm-msse/ab...

🧵 1/7

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Joachim Nielsen @joachimnielsen.bsky.social · Aug 24

Elegant study on glycogen using the one-legged exercise model:

Exercise- and diet-induced glycogen depletion impairs performance during one-legged constant-load, high-intensity exercise in humans

Thomassen, McKenna, Olmedillas, Wyckelsma, Bangsbo, Nordsborg
www.frontiersin.org/journals/phy...

Reposted by Joachim Nielsen

Sakamoto Lab @labsakamoto.bsky.social · Aug 21

Congratulations to Researcher @itsmedipsikha.bsky.social for being one of the recipients of the EFSD/Lilly Young Investigator Awards! We celebrated her achievement with some cakes and bubbles earlier 🥳 @easdnews.bsky.social @cbmr.science

www.europeandiabetesfoundation.org/recipients/e...

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Joachim Nielsen @joachimnielsen.bsky.social · Aug 13

Join our PhD course in metabolism and EC coupling.
November 10-15. University of Southern Denmark.
Enrol here: www.sdu.dk/en/forskning...

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Reposted by Joachim Nielsen

Javier Gonzalez @j-t-gonzalez.bsky.social · Aug 12

New paper!

Do ketone esters affect post-exercise recovery?

doi.org/10.1007/s003...

#ketones #exercise #sports #nutrition #recovery

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Joachim Nielsen @joachimnielsen.bsky.social · Aug 7

www.biorxiv.org/content/10.1...

Glycogen metabolism in mouse embryonic Sertoli cells sustains the germ line through the lactate shuttle

Metabolites are key regulators of cell fate decisions, epigenetic remodeling, and lineage commitment. While genetic pathways governing testis differentiation are well studied, the role of metabolism r...

www.biorxiv.org

Reposted by Joachim Nielsen

Kevin Murach @kevinmurachphd.bsky.social · Aug 6

“Muscle memory theory: A critical evaluation” in @JPhysiol led by postdoc Nate Serrano physoc.onlinelibrary.wiley.com/doi/10.1113/...

Muscle memory theory: A critical evaluation

Click on the article title to read more.

physoc.onlinelibrary.wiley.com

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The Journal of Physiology @jphysiol.bsky.social · Jul 31

#Research by Léo Blervaque et al. examines #capillary-to-sarcolemma distance and location of cytochrome c oxidase, offering insights for maximal O2 uptake and muscle lactate release in trained athletes 🚴‍♂️ 🔎

📜 Read the study here: physoc.onlinelibrary.wiley.com/doi/10.1113/...

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