Reactive hyperemia: a review of methods, mechanisms, and considerations

AJP Regulatory Integrative and Comparative Physiology, Journal Year: 2020, Volume and Issue: 318(3), P. R605 - R618

Published: Feb. 5, 2020

Reactive hyperemia is a well-established technique for noninvasive assessment of peripheral microvascular function and predictor all-cause cardiovascular morbidity mortality. In its simplest form, reactive represents the magnitude limb reperfusion following brief period ischemia induced by arterial occlusion. Over past two decades, investigators have employed variety methods, including brachial artery velocity Doppler ultrasound, tissue near-infrared spectroscopy, distension venous occlusion plethysmography, tonometry, to measure hyperemia. Regardless used hyperemia, blunted believed reflect impaired function. With advent several technological advancements, together with an increased interest in microcirculation, becoming more common as research tool widely across multiple disciplines. this mind, we sought review various methodologies commonly assess current mechanistic pathways contribute on methodological considerations.

Language: Английский

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Pathophysiology of Exercise Intolerance and Its Treatment With Exercise-Based Cardiac Rehabilitation in Heart Failure With Preserved Ejection Fraction

Journal of Cardiopulmonary Rehabilitation and Prevention, Journal Year: 2019, Volume and Issue: 40(1), P. 9 - 16

Published: Nov. 25, 2019

Heart failure with preserved ejection fraction (HFpEF) is the fastest growing form of heart in United States. The cardinal feature HFpEF reduced exercise tolerance (peak oxygen uptake, JOURNAL/jcprh/04.03/01273116-202001000-00003/3FSM1/v/2023-09-11T232142Z/r/image-gif o 2peak ) secondary to impaired cardiac, vascular, and skeletal muscle function. There are currently no evidence-based drug therapies improve clinical outcomes patients HFpEF. In contrast, training a proven effective intervention for improving , aerobic endurance, quality life patients. This brief review discusses pathophysiology intolerance role clinically stable It also mechanisms responsible training–mediated improvements Finally, it provides prescription guidelines cardiac rehabilitation specialists assist them safely implementing exercise-based programs

Language: Английский

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Sustained fatigue assessment during isometric exercises with time-domain near infrared spectroscopy and surface electromyography signals

Biomedical Optics Express, Journal Year: 2020, Volume and Issue: 11(12), P. 7357 - 7357

Published: Nov. 18, 2020

The effect of sustained fatigue during an upper limb isometric exercise is presented to investigate a group healthy subjects with simultaneous time-domain (TD) NIRS and surface electromyography (sEMG) recordings on the deltoid lateralis muscle. aim work was understand which TD-NIRS parameters can be used as descriptors for muscular fatigue, focusing slow phase this process using median frequency (MF) computed from sEMG gold standard measure. It found that oxygen saturation deoxy-hemoglobin are slightly better than oxy-hemoglobin, since they showed higher correlation MF, while total-hemoglobin MF lower.

Language: Английский

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Matching of O2 Utilization and O2 Delivery in Contracting Skeletal Muscle in Health, Aging, and Heart Failure

Frontiers in Physiology, Journal Year: 2022, Volume and Issue: 13

Published: June 14, 2022

Skeletal muscle is one of the most dynamic metabolic organs as evidenced by increases in rate >150-fold from rest to maximal contractile activity. Because limited intracellular stores ATP, activation pathways required maintain necessary rates ATP re-synthesis during sustained contractions. During very early phase, phosphocreatine hydrolysis and anaerobic glycolysis prevails but activity extends beyond ∼1 min, oxidative phosphorylation becomes major ATP-generating pathway. Oxidative metabolism macronutrients highly dependent on cardiovascular system deliver O 2 contracting fibres, which ensured through a tight coupling between skeletal utilization delivery. However, what extent delivery ideal terms enabling optimal function context-dependent determined complex interaction several regulatory systems. The first part review focuses local systemic mechanisms involved regulation how integration these influences matching demand In second part, alterations structure associated with aging heart failure, impact function, will be addressed. Where applicable, potential exercise training offset/reverse age- disease-related declines highlighted context function. human data also covers animal observations.

Language: Английский

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

Journal of Applied Physiology, Journal Year: 2019, Volume and Issue: 127(5), P. 1328 - 1337

Published: Sept. 12, 2019

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 BF index (BF i ) in human skin, muscle, breast, brain, and other tissue types. this study, we proposed new motion correction algorithm DCS-derived able to remove artifacts during cycling exercise. We tested on DCS data collected exercise demonstrated that can be used quantify muscle dynamic high-intensity addition, measured regional oxygen metabolic rate (MRO 2i by combining frequency-domain multidistance (FDNIRS) oximetry with measures. Recreationally active subjects ( n = 12; 31 ± 8 183 4 cm, 79 10 kg) pedaled at 80–100 revolutions/min until volitional fatigue work increase 30 W every min. Exercise intensity was normalized each subject power peak (W ). Both rectus femoris MRO increased from 15% up 75% then plateaued end During recovery power, remained almost constant, whereas started decrease. The /MRO plateau associated rising lactate concentration, indicating progressive involvement anaerobic metabolism. These findings further highlight utility FDNIRS effective, reproducible, techniques assess real time such cycling. NEW & NOTEWORTHY To best our knowledge, study is first demonstrate combination monitor quadriceps metabolism high temporal resolution optically parameters confirm expected relationship between flow, oxidative metabolism, production

Language: Английский

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Deep-learning-based separation of shallow and deep layer blood flow rates in diffuse correlation spectroscopy

Biomedical Optics Express, Journal Year: 2023, Volume and Issue: 14(10), P. 5358 - 5358

Published: Sept. 13, 2023

Diffuse correlation spectroscopy faces challenges concerning the contamination of cutaneous and deep tissue blood flow. We propose a long short-term memory network to directly quantify flow rates shallow deep-layer tissues. By exploiting different contributions auto-correlation functions, we accurately predict (RMSE = 0.047 0.034 ml/min/100 g simulated tissue, R2 0.99 0.99, respectively) in two-layer phantom experiment. This approach is useful evaluating responses active muscles, where both deep-muscle increase with exercise.

Language: Английский

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Impact of supine exercise on muscle deoxygenation kinetics heterogeneity: mechanistic insights into slow pulmonary oxygen uptake dynamics

Journal of Applied Physiology, Journal Year: 2020, Volume and Issue: 129(3), P. 535 - 546

Published: July 23, 2020

Oxygen uptake (V̇o2) kinetics are slowed in the supine (S) position purportedly due to impaired muscle O2 delivery ([Formula: see text]); however, these conclusions predicated on single-site measurements superficial using continuous-wave near-infrared spectroscopy (NIRS). This study aimed determine impact of body [i.e., upright (U) versus S] deep and deoxygenation (deoxy[heme]) time-resolved (TR-) NIRS, how relate pulmonary V̇o2 kinetics. Seventeen healthy men completed constant power tests during 1) S heavy-intensity exercise 2) U at same absolute work rate, with a subset 10 completing additional relative rate as S. Pulmonary was measured breath-by-breath and, deoxy- total[heme] were resolved via TR-NIRS vastus lateralis rectus femoris. The fundamental phase time increased compared (S: 36 ± vs. U: 27 8 s; P < 0.001). deoxy[heme] amplitude 25-28 13-18 µM; 0.05) 17-20 9-16 greater consistent for (above data) rates (n = 10, all 0.05). amplitudes supports that reduced perfusive [Formula: text] S, even within muscle, necessitated reliance fractional extraction diffusive text]. slower demonstrates that, ultimately, adjustments insufficient prevent impairments whole oxidative metabolism.NEW & NOTEWORTHY We show causes degree both increases spatial heterogeneity deoxygenation. Therefore, this suggests any gradient toward is mitigate function response delivery. More heterogeneous associated

Language: Английский

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Determinants of skeletal muscle oxygen consumption assessed by near-infrared diffuse correlation spectroscopy during incremental handgrip exercise

Journal of Applied Physiology, Journal Year: 2019, Volume and Issue: 127(3), P. 698 - 706

Published: July 18, 2019

Near-infrared diffuse correlation spectroscopy (DCS) is a rapidly evolving optical imaging technique for the assessment of skeletal muscle O2 utilization (mVO2). We compared DCS-derived determinants mVO2 with conventional measures [blood flow by brachial artery Doppler ultrasound and venous saturation (SVO2)] in eight volunteers at rest during incremental handgrip exercise. Brachial blood index (BFI) were linearly related (R2 = 0.57) increased each workload, whereas SVO2 decreased from 65.3 ± 2.5% (rest) to 39.9 3.0% (light exercise; P < 0.01) no change thereafter. In contrast, tissue progressively stage (P 0.01), driven almost entirely an initial steep rise deoxyhemoglobin/myoglobin, followed linear increase Whereas seemingly disparate first glance, we believe these two approaches provide similar information. Indeed, plotting mean convective delivery diffusive conductance, show that transition exercise was achieved greater conductance versus (10-fold vs. 4-fold increase, respectively), explaining decline SVO2. light heavy equal increases (1.8-fold) plateau That BFI deoxyhemoglobin/myoglobin (surrogate measure extraction) share same general biphasic pattern suggests both DCS complementary information regarding mVO2.NEW & NOTEWORTHY emerging quantifying microvascular level. Here, provides insight into consumption across wide range intensities, further establishing utility DCS.

Language: Английский

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

Frontiers in Physiology, Journal Year: 2022, Volume and Issue: 13

Published: Sept. 12, 2022

The process of matching skeletal muscle blood flow to metabolism is complex and multi-factorial. In response exercise, increases in cardiac output, perfusion pressure local vasodilation facilitate an intensity-dependent increase flow. Concomitantly, sympathetic nerve activity directed both exercising non-active muscles as a function exercise intensity. Several studies have reported the presence tonic vasoconstriction vasculature at onset that persists through prolonged bouts, though it blunted exercise-intensity dependent manner (functional sympatholysis). collective evidence has resulted current dogma vasoactive molecules released from muscle, vascular endothelium, possibly red cells produce vasodilation, while restrains direct most metabolically active muscles/fibers. Vascular smooth assumed integrate host signals resulting precise metabolism. Unfortunately, critical review available literature reveals published largely focused on bulk existing experimental approaches with limited ability reveal metabolism, particularly between within muscles. This paper will our understanding regulation contracting highlight areas where further investigation necessary.

Language: Английский

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Epinephrine iontophoresis attenuates changes in skin blood flow and abolishes cutaneous contamination of near-infrared diffuse correlation spectroscopy estimations of muscle perfusion

AJP Regulatory Integrative and Comparative Physiology, Journal Year: 2023, Volume and Issue: 324(3), P. R368 - R380

Published: Jan. 24, 2023

Near-infrared diffuse correlation spectroscopy (NIR-DCS) is an optical imaging technique for measuring relative changes in skeletal muscle microvascular perfusion (i.e., fold change above baseline) during reactive hyperemia testing and exercise reported as a blood flow index (BFI). Although it generally accepted that BFI are primarily driven by perfusion, well known large, hyperthermia-induced cutaneous can uncouple this relationship. What remains unknown, how much of impact have on NIR-DCS estimates under thermoneutral conditions, where assumed to be relatively low. We therefore used epinephrine iontophoresis pharmacologically block throughout battery experimental procedures. The data show 1) attenuates up 4-h posttreatment, even the face significant neural local stimuli, 2) does not significantly or moderate-intensity exercise, 3) passive whole body heat stress, when vasodilation pronounced, preserves measures exercise. Collectively, these suggest unlikely major but abolish contamination signal studies skin may elevated specific interest.

Language: Английский

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