mNIRS

Muscle blood flow (mBF) and muscle oxygen consumption (mVO₂) are the dominant physiological processes that influence mNIRS oxygen saturation measurements; and of course, these values are of interest in their own right.  The response of mNIRS signals to an occlusion is a simple way of making these measurements. In a later post, I will describe the arterial occlusion (AO) method to measure mVO₂. This is very popular, partly I suspect because sports scientists and physiologists love – and are really familiar – with measuring whole body oxygen consumption (VO₂); so they are emotionally and scientifically receptive to an oxygen consumption number. Of course, it helps that measuring mVO₂  at different times post exercise has become a way of measuring mitochondrial capacity. Both the AO method and its use to measure mitochondrial capacity will be the subject of future education blogs.  However, this blog will focus on the less common use of a venous occlusion (VO) to measure mBF...

  As promised here is a guest blog by my colleague Chris McManus. Chris went to Pavia and gave an invited lecture describing his new software for measuring mitochondrial oxidative capacity –   MCMITO.   Apparently the Mc in McMito is not eponymous but is named in honour of Kevin McCully who has been the champion of this mNIRS method. Hearing about the exciting new devices being showcased by the manufactures/sponsors made me very jealous at having missed out on getting to Pavia myself. Here is Chris’s report.     REFLECTIONS ON MNIRS 2026   More than a venue Having now had time to reflect on mNIRS 2026 in Pavia, I keep coming back to one thing. The city was beautiful, the venue worked well and the organisation was excellent, so thank you again to Simone, Andrea and the organising committee. But what made it special was the community.   Having hosted the first conference at the University of Essex in 2024, it was great to see it grow. This year we welcom...

  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...

Muscle near infrared spectroscopy (mNIRS) has developed enormously since Frans Jöbsis first demonstrated in 1977 that near infrared light could be used to monitor oxygen-sensitive signals in living tissue. Today there is a wide range of instruments and an equally wide range of ways in which NIRS is used to study muscle. This is a strength of the field, but it can also make it difficult to understand exactly what different instruments measure, how those measurements are obtained and, most importantly, what they tell us about muscle physiology. I’ve been working with NIRS and oxygen metabolism for many years, and I’ve created MuscleNIRS as a place to discuss some of these questions. The site has two main parts. The  Education  section contains short introductions to the measurements that can be made with mNIRS and the methods used to make them. These are intended to be relatively permanent resources and will be expanded over time. The  Blog  will be less formal and mor...

Methods other than SRS use multiple source–detector distances to estimate StO₂. While the methods vary, a shared principle is that shorter distances sample more superficial tissues, while longer distances sample deeper regions — such as the cerebral cortex or muscle tissue. These methods are sometimes loosely referred to as spatial resolution or self-calibrating approaches and, confusingly, the term spatially resolved spectroscopy is also occasionally used. Importantly, however, these methods do not use the same analytical approach as the classic SRS algorithms used in systems such as the Hamamatsu NIRO or Artinis PortaMon. Among commercial devices, the most widely used has probably been the INVOS system, now sold by Medtronic. The traditional adult sensor uses detectors placed 3 cm and 4 cm from the source. The signal from the shorter separation, which is more sensitive to superficial tissue, is used to reduce the superficial contribution to the signal measured at the longer separatio...