Understanding near infrared spectroscopy and its application to skeletal muscle research

Abstract

Near infrared spectroscopy (NIRS) is a powerful noninvasive tool with which to study the matching of oxygen delivery to oxygen utilization and the number of new publications utilizing this technique has increased exponentially in the last 20 yr. By measuring the state of oxygenation of the primary heme compounds in skeletal muscle (hemoglobin and myoglobin), greater understanding of the underlying control mechanisms that couple perfusive and diffusive oxygen delivery to oxidative metabolism can be gained from the laboratory to the athletic field to the intensive care unit or emergency room. However, the field of NIRS has been complicated by the diversity of instrumentation, the inherent limitations of some of these technologies, the associated diversity of terminology, and a general lack of standardization of protocols. This Cores of Reproducibility in Physiology (CORP) will describe in basic but important detail the most common methodologies of NIRS, their strengths and limitations, and discuss some of the potential confounding factors that can affect the quality and reproducibility of NIRS data. Recommendations are provided to reduce the variability and errors in data collection, analysis, and interpretation. The goal of this CORP is to provide readers with a greater understanding of the methodology, limitations, and best practices so as to improve the reproducibility of NIRS research in skeletal muscle.

Studies into the determinants of skeletal muscle oxygen consumption: novel insight from near‐infrared diffuse correlation spectroscopy

“…; Grassi & Quaresima, ; Sun et al . ; Barstow, ). That tissue saturation declined with rhythmic handgrip exercise between 20 and 30% MVC is entirely consistent with several previous investigations (Boushel et al .…”

“…; Grassi & Quaresima, ; Sun et al . ; Barstow, ) – introduces exciting new possibilities for understanding the determinants of muscle oxygen utilization at the microvascular level. Several laboratories have already combined DCS with conventional NIRS during exercise, establishing good ‘proof‐of‐concept’ (Henry et al .…”

Relationship between (non)linear phase II pulmonary oxygen uptake kinetics with skeletal muscle oxygenation and age in 11–15 year olds

“…A differential path‐length factor (DPF) of 4 cm was employed to account for tissue scattering. Since assuming a constant DPF using CW‐NIRS cannot resolve absolute [Hb+Mb] concentrations (Barstow, ), the Δdeoxy[Hb+Mb] amplitude was normalized relative to the end‐exercise value prior to kinetic analysis in each condition. The tissue oxygenation index (TOI; oxy[Hb+Mb]/oxy[Hb+Mb] + deoxy[Hb+Mb], expressed as a percentage) was also calculated by spatially resolved spectroscopy as the TOI is thought to be less sensitive to changes in microvascular volume than are deoxy[Hb+Mb] data (Quaresima & Ferrari, ).…”

Effect of differential muscle activation patterns on muscle deoxygenation and microvascular haemoglobin regulation

“…Near‐infrared spectroscopy is generally considered to measure only small blood vessels (e.g. Barstow, ). In particular, time‐resolved NIRS (TR‐NIRS) was used to investigate non‐invasively the matching {via deoxy[haemoglobin + myoglobin] (deoxy[Hb + Mb]) and tissue O 2 saturation ()} and microvascular haematocrit (via total[Hb + Mb]) within specific muscle regions (Federspiel & Popel, ; Groebe & Thews, ; Koga et al., , ; Okushima et al., ).…”

“…Nearinfrared spectroscopy is generally considered to measure only small blood vessels (e.g. Barstow, 2019 (Federspiel & Popel, 1986;Groebe & Thews, 1990;Koga et al, 2012Koga et al, , 2017Okushima et al, 2016…”