Diffuse correlation spectroscopy and frequency-domain near-infrared spectroscopy for measuring microvascular blood flow in dynamically exercising human muscles

Abstract

In the last 20 yr, near-infrared diffuse correlation spectroscopy (DCS) has been developed for providing a noninvasive estimate of microvascular blood flow (BF) as a BF index (BFi) in the human skin, muscle, breast, brain, and other tissue types. In this study, we proposed a new motion correction algorithm for DCS-derived BFi able to remove motion artifacts during cycling exercise. We tested this algorithm on DCS data collected during cycling exercise and demonstrated that DCS can be used to quantify muscle BFi during dynamic high-intensity exercise. In addition, we measured tissue regional oxygen metabolic rate (MRO2i) by combining frequency-domain multidistance near-infrared spectroscopy (FDNIRS) oximetry with DCS flow measures. Recreationally active subjects ( n = 12; 31 ± 8 yr, 183 ± 4 cm, 79 ± 10 kg) pedaled at 80–100 revolutions/min until volitional fatigue with a work rate increase of 30 W every 4 min. Exercise intensity was normalized in each subject to the cycling power peak (Wpeak). Both rectus femoris BFi and MRO2i increased from 15% up to 75% Wpeak and then plateaued to the end of the exercise. During the recovery at 30 W cycling power, BFi remained almost constant, whereas MRO2i started to decrease. The BFi/MRO2i plateau was associated with the rising of the lactate concentration, indicating the progressive involvement of the anaerobic metabolism. These findings further highlight the utility of DCS and FDNIRS oximetry as effective, reproducible, and noninvasive techniques to assess muscle BFi and MRO2i in real time during a dynamic exercise such as cycling. NEW & NOTEWORTHY To the best of our knowledge, this study is the first to demonstrate that diffuse correlation spectroscopy in combination with frequency-domain near-infrared spectroscopy can monitor human quadriceps microvascular blood flow and oxygen metabolism with high temporal resolution during a cycling exercise. The optically measured parameters confirm the expected relationship between blood flow, muscle oxidative metabolism, and lactate production during exercise.

Improved accuracy of cerebral blood flow quantification in the presence of systemic physiology cross-talk using multi-layer Monte Carlo modeling

“…5,8 DCS takes advantage of this physical phenomenon to monitor time-varying blood flow non-invasively and is currently being used in various research applications. 5,[8][9][10][11][12][13][14][15] A particularly successful application area is the CBF monitoring of neonates, for whom the relatively thin skull results in high brain sensitivity. 16,17 Extending the application of DCS to bedside brain monitoring of adults, however, requires accounting for the influence of systemic variations of scalp blood flow (SBF) that have the potential to strongly contaminate changes in the calculated cerebral blood flow index (CBF i ).…”

Impact of supine versus upright exercise on muscle deoxygenation heterogeneity during ramp incremental cycling is site specific

“…Further investigations and technological developments (e.g. combined NIRS and diffuse correlation spectroscopy, Quaresima et al 2019 ) are, therefore, required to determine how differences in muscle activation and/or local O 2 might contribute to the unique O 2 transport characteristics of the VLd noted herein.…”

Microvascular blood flow changes of the abductor pollicis brevi muscle during sustained static exercise

“…However, DCS is sensitive to fiber and probe motion. For this reason its usage in dynamic, rhythmically exercise requires signal gating in order to exclude the time periods corresponding to limb movement [48–50]. We have chosen to perform an isometric exercise in order to avoid motion artifacts in DCS recording.…”