mNIRS 2026 initial thoughts and my new favourite mNIRS experiment!

 I couldn’t make it to Pavia unfortunately. For a look at what you and I missed click here.  Fortunately for us all, we will be updating the blog with highlights over the coming months. First the meeting organiser sent me this report. 

“With participants from all around the world and a programme that ranged from metabolic myopathies to intensive care, from paediatric oncology to wearable technology, mNIRS2026 confirmed that our community has never been more active.

A few highlights from the science: Bruno Grassi opened with a compelling keynote on mNIRS in metabolic myopathies; Rogerio Suarez showed how the post-occlusive reperfusion slope outperforms conduit artery FMD as a marker of microvascular health; Stefan Perrey and Rebecca Re gave us a shared language for the technique's physics and limitations; Chris McManus presented McMito, a free platform for standardised mitochondrial capacity assessment; Richie Goulding reminded us that invasive validation matters; and the clinical sessions on COPD, paediatric oncology, heart failure, bed rest, and intensive care fluid therapy showed just how broad the field has become. The flash poster session and the oral communications brought outstanding early-career science into the mix.

What the transcripts cannot capture: the dinner, the conversations over espresso in the Cortile delle Magnolie, and the ideas that started there. Those are the real engine of a community, and you made them happen.

A warm thank you goes also to our sponsors! mNIRS2026 would not have been possible without the generous support of our sponsors. We extend our sincere gratitude to each of them for believing in this community and making the meeting a reality.

Save the date — the next International Meeting on Muscle Near-Infrared Spectroscopy will take place in France in 2028. More details to follow, but block a slot in your calendar now.”

We look forward to seeing you in France in 2028.

With warmest regards,

Simone Porcelli”

My colleague from Essex, Chris McManus, who did attend will provide his own views of the meeting in a guest blog in a few weeks time. 

Selected highlight videos from many of the talks will be posted on mNIRS.org and our muscle NIRS YouTube channel (where you can already see videos from mNIRS 2024). When will we drop the mNIRS 2026 videos? Subscribe at mNIRS.org and we’ll let you know as soon as we do! 

In fact, I got a sneak preview of these excellent talks and thought I would share with you one of my favourites. As the title of this blog highlights, this included my favourite new mNIRS tool (which will eventually feature on the education section, but as it is a bit specialised it will have to wait its turn). 

The talk was by one of the local organisers, Andrea Pilotto at University of Pavia. Entitled “Muscle O₂ Diffusion Resistance and intramuscular O₂ flow Limitations: insights from NIRS”. It described the method developed by Andrea with Simone Porcelli and others of measuring mitochondrial capacity at different muscle oxygen saturations. To back up a moment, what are mitochondrial capacity measurements? These too will eventually feature in our education section (of course). But essentially they involve measuring the recovery rate of oxygen consumption back to normal after an exercise bout. This correlates with the PCr/Pi recovery rate measured by ³¹P magnetic resonance spectroscopy (MRS). That PCr/Pi recovery rate correlates with the amount of mitochondria in the muscle. Hence the term “mitochondrial capacity measurement”. 

To measure mitochondrial capacity in mNIRS you use the arterial occlusion method to measure muscle oxygen consumption (coming to the education site soon!). You get a pretty much exponential decline in this rate; so you can measure a recovery rate (tau) or half time (t_1/2). The genius of the Pilotto/Porcelli method is that by doing the mitochondrial capacity measurement at different StO₂ levels, you in effect get to see whether different levels of oxygen effect mitochondrial energetics. 

The method is described here 

Pilotto, A.M., Adami, A., Mazzolari, R., Brocca, L., Crea, E., Zuccarelli, L., Pellegrino, M.A., Bottinelli, R., Grassi, B., Rossiter, H.B. and Porcelli, S. (2022), Near-infrared spectroscopy estimation of combined skeletal muscle oxidative capacity and O₂ diffusion capacity in humans. J Physiol, 600: 4153-4168. https://doi.org/10.1113/JP283267

At mNIRs 2024, Andrea presented a poster showing that older subjects had no StO2 effect on muscle oxidative capacity, whereas in younger subjects there was a pronounced effect (the capacity was lower as StO2 fell). Middle-age subjects came appropriately in the middle. He concluded that mitochondrial function became less limited by oxygen diffusion the older you got. Of course, the absolute capacity is lower as you age. But it looks like your blood flow does not deteriorate as much as your number of mitochondria. At mNIRS 2026 he showed, perhaps surprisingly, that elite swimmers and recreational swimmers had the same StO2 dependence on mitochondrial capacity. Of course, the elite had higher absolute values, but the balance between supply and capacity seemed unaltered. Bear in mind I am a biochemist, so I am probably expressing this idea in a slightly different interpretative framework to that of a physiologist. But I hope I am not misrepresenting it too much. 

Villanova, S.,  Pastorio, E.,  Pilotto, A. M.,  Marciano, A.,  Quaresima, V.,  Adami, A.,  Rossiter, H. B.,  Cardinale, D. A., & Porcelli, S. (2025).  Oxidative and O2 diffusive function in triceps brachii of recreational to world class swimmers. Experimental Physiology,  110,  1721-1731.    https://doi.org/10.1113/EP092299

Why am I so interested in this method? Well. in my non-NIRS research life I was (am still?) a mitchondrial bioenergeticist. One of my most productive research areas was the effect of oxygen on mitochondrial respiration. Indeed, my second most cited non review research paper was looking at the effects of nitric oxide (NO) on mitochondrial respiration.

Brown GC, Cooper CE. Nanomolar concentrations of nitric oxide reversibly inhibit synaptosomal respiration by competing with oxygen at cytochrome oxidase. FEBS Lett. 1994 Dec 19;356(2-3):295-8. doi: 10.1016/0014-5793(94)01290-3. PMID: 7805858

At low NO levels the K_m for mitochondrial oxygen consumption is increased and respiration is inhibited; the response is reversible and potentially of physiological relevance. However, the research stalled as we couldn’t really see a way of testing this in vivo. Maybe -  just maybe - we now have a way of doing this. Now where did I put all those nitric oxide synthase inhibitors?