Rapid vasodilation within contracted skeletal muscle in humans: new insight from concurrent use of diffuse correlation spectroscopy and Doppler ultrasound

Abstract

Previous studies showed that conduit artery blood flow rapidly increases after even a brief contraction of muscles within the dependent limb. Whether this rapid hyperemia occurs within contracted skeletal muscle in humans has yet to be confirmed, however. We therefore used diffuse correlation spectroscopy (DCS) to characterize the rapid hyperemia and vasodilatory responses within the muscle microvasculature induced by single muscle contractions in humans. Twenty-five healthy male volunteers performed single 1-s isometric handgrips at 20%, 40%, 60% and 80% of maximum voluntary contraction (MVC). DCS probes were placed on the flexor digitorum superficialis muscle, and a skeletal muscle blood flow index (SMBFI) was derived continuously. At the same time, brachial artery blood flow (BABF) responses were measured using Doppler ultrasound. Single muscle contractions evoked rapid, monophasic increases in both SMBFI and BABF that occurred within 3 s after release of contraction. The initial and peak responses increased with increases in contraction intensity and were greater for BABF than for SMBFI at all intensities. BABF reached its peak within 5 to 8 s after the end of contraction. The SMBFI continued to increase after the BABF passed its peak and was decreasing toward the resting level and peaked about 10 to 15 s after completion of the contraction. We conclude that single muscle contractions induce rapid, intensity-dependent hyperemia within the contracted skeletal muscle microvasculature. Moreover, the characteristics of the rapid hyperemia and vasodilatory responses of skeletal muscle microvessels differ from that simultaneously evaluated in the upstream conduit artery.

Uphill versus downhill high-intensity training effectiveness in preserving vascular function and exercise performance in runners who reduce their regular endurance training

“…Single muscle contraction-induced vasodilation [ 21 – 23 , 26 , 27 ] is not a gold-standard measure of vascular or endothelial function. However, this measure along with the focus on VC allows to evaluate changes in the global vasodilation capacity of the leg [ 16 , 38 ], which is predominantly nitric oxide dependent and includes changes at the microvascular level [ 21 , 24 , 27 , 32 , 38 ]. Changes in VC responses to mechanical stimuli are of particular interest for vascular physiology as this variable is involved in the precise regulation of muscle blood flow along with the mean arterial pressure [ 13 ].…”

Evaluation of Local Skeletal Muscle Blood Flow in Manipulative Therapy by Diffuse Correlation Spectroscopy

“…Simultaneous measurement of muscle blood flow, systemic blood pressure, and electrocardiogram (ECG) was performed when participants were in a prone position. Optical probes of the DCS system developed in-house ( Nakabayashi and Ono, 2017 ; Ichinose et al, 2018 ; Nakabayashi et al, 2018 ; Ono et al, 2018 , Ichinose et al, 2019 , 2021 ) were attached to the skin surface just above the superior fibers of the right trapezius muscle at the center of the line, connecting the spinous process of the seventh cervical vertebra and the acromion of the right scapula to monitor the local blood flow ( Figure 1 ). The optical probes were secured on the skin surface with a medical adhesive tape (see Supplementary Video S1 for a more detailed fixation procedure of the optical probes).…”

“…Perfusion MRI techniques, which offer minimally or non-invasive measures of blood flow in the skeletal muscle ( Wigmore et al, 2004 ; Englund and Langham, 2020 ), are also unsuitable for monitoring the therapeutic effect of MT, as it requires physical manipulation. The ultrasound Doppler method is another non-invasive technique for measuring tissue blood flow ( Saltin et al, 1998 ; Kitano et al, 2005 ; Ichinose et al, 2021 ). However, changes in tissue microcirculation from locally applied MT might not be captured with the ultrasound Doppler method, which detects the total blood flow of the conduit vessels connected to the whole limb.…”

Does sympathetic vasoconstriction contribute to metabolism: Perfusion matching in exercising skeletal muscle?

“…Diffuse correlational spectroscopy (DCS) is an emerging noninvasive technology that has been applied during exercise by several laboratories ( Hammer et al, 2018 ; Tucker et al, 2019 ; Ichinose et al, 2021 ). Combining DCS with widely used near infrared spectroscopy (NIRS) allows continuous measurement of blood flow and has been validated against several standards including microspheres ( Zhou et al, 2009 ) and arterial spin labelled MRI ( Yu et al, 2007 ).…”