Skeletal muscle microvascular and respiratory responses to exercise in healthy and T2D adults: agreement and reproducibility study of NIRS technologies.

Authors

Adam A Luco, Martin Gram, Inge Ramakers, Terence Ryan, Osvaldo Enriquez, James Faulkner, Lee Stoner, David S Rowlands

Published in

European journal of applied physiology. Jun 29, 2026. Epub Jun 29, 2026.

Abstract

Continuous wave (CW) near-infrared spectroscopy (NIRS) is widely used in skeletal muscle tissue hemodynamic and respiratory research utilizing fixed light scattering assumptions.
Compare reproducibility and technical characteristics of CW-NIRS against frequency-domain (FD)-NIRS, which allows for intra-individual scattering correction.
Muscle blood flow (mBF) and oxygen uptake ([Formula: see text]) (using rapid-occlusions), and perfusion were assessed with NIRS in 10 healthy (ND) and 10 type-2 diabetic (T2D) men at rest and during knee extensions at 5% and 15% of maximal voluntary contraction (MVC) on three occasions within 10 days.
In both groups, exercise responses for mBF and [Formula: see text] were not substantially different between technology with moderate-high between-day reproducibility (ICC range 0.72-0.98). However, compared to FD-NIRS, CW-NIRS perfusion substantially higher at rest (21 uM; 90%CI 29-13), 5%MVC (18 uM; 27-9) and 15%MVC (17 uM; 26-8) in T2D, but not ND. Standardized typical errors during exercise were small-moderate: e.g., 15%MVC mBF, CW-NIRS (ND 0.45; T2D 0.49), FD-NIRS (0.35; 0.49); mV̇O₂, CW-NIRS (0.24; 0.26), FD-NIRS (0.45; 0.32); perfusion CW-NIRS (0.25; 0.25) and FD-NIRS (0.25; 0.23); and, not different between groups and technology.
Both NIRS technologies are reproducible. CW-NIRS assumptions work for muscle blood flow and oxygen use at rest and during exercise. FD-NIRS might be better at detecting changes in perfusion during exercise, especially in older or clinical groups. However, FD-NIRS is more expensive and complex, making it less practical.

PMID:
42371077
Bibliographic data and abstract were imported from PubMed on 14 Aug 2026.

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