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W. Larry Kenney - One of the best experts on this subject based on the ideXlab platform.
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Historical reviews of the assessment of human cardiovascular function: interrogation and understanding of the control of Skin Blood Flow
European Journal of Applied Physiology, 2020Co-Authors: Helen Jones, N. Tim Cable, Lacy M. Alexander, W. Larry KenneyAbstract:Several techniques exist for the determination of Skin Blood Flow that have historically been used in the investigation of thermoregulatory control of Skin Blood Flow, and more recently, in clinical assessments or as an index of global vascular function. Skin Blood Flow measurement techniques differ in their methodology and their strengths and limitations. To examine the historical development of techniques for assessing Skin Blood Flow by describing the origin, basic principles, and important aspects of each procedure and to provide recommendations for best practise. Venous occlusion plethysmography was one of the earliest techniques to intermittently index a limb’s Skin Blood Flow under conditions in which local muscle Blood Flow does not change. The introduction of laser Doppler Flowmetry provided a method that continuously records an index of Skin Blood Flow (red cell flux) (albeit from a relatively small Skin area) that requires normalisation due to high site-to-site variability. The subsequent development of laser Doppler and laser speckle imaging techniques allows the mapping of Skin Blood Flow from larger surface areas and the visualisation of capillary filling from the dermal plexus in two dimensions. The use of iontophoresis or intradermal microdialysis in conjunction with laser Doppler methods allows for the local delivery of pharmacological agents to interrogate the local and neural control of Skin Blood Flow. The recent development of optical coherence tomography promises further advances in assessment of the Skin circulation via three-dimensional imaging of the Skin microvasculature for quantification of vessel diameter and vessel recruitment.
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Changes in the control of Skin Blood Flow with exercise training: where do cutaneous vascular adaptations fit in?
Experimental physiology, 2011Co-Authors: Grant H. Simmons, Lacy A. Holowatz, Brett J. Wong, W. Larry KenneyAbstract:Heat is the most abundant byproduct of cellular metabolism. As such, dynamic exercise in which a significant percentage of muscle mass is engaged generates thermoregulatory demands that are met in part by increases in Skin Blood Flow. Increased Skin Blood Flow during exercise adds to the demands on cardiac output and confers additional circulatory strain beyond that associated with perfusion of active muscle alone. Endurance exercise training results in a number of physiological adaptations which ultimately reduce circulatory strain and shift thermoregulatory control of Skin Blood Flow to higher levels of Blood Flow for a given core temperature. In addition, exercise training induces peripheral vascular adaptations within the cutaneous microvasculature indicative of enhanced endothelium-dependent vasomotor function. However, it is not currently clear how (or if) these local vascular adaptations contribute to the beneficial changes in thermoregulatory control of Skin Blood Flow following exercise training. The purpose of this Hot Topic Review is to synthesize the literature pertaining to exercise training-mediated changes in cutaneous microvascular reactivity and thermoregulatory control of Skin Blood Flow. In addition, we address mechanisms driving changes in cutaneous microvascular reactivity and thermoregulatory control of Skin Blood Flow, and pose the question: what (if any) is the functional role of increased cutaneous microvascular reactivity following exercise training?
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Peripheral mechanisms of thermoregulatory control of Skin Blood Flow in aged humans
Journal of applied physiology (Bethesda Md. : 1985), 2010Co-Authors: Lacy A. Holowatz, W. Larry KenneyAbstract:Human Skin Blood Flow is controlled via dual innervation from the sympathetic nervous system. Reflex cutaneous vasoconstriction and vasodilation are both impaired with primary aging, rendering the aged more vulnerable to hypothermia and cardiovascular complications from heat-related illness. Age-related alterations in the thermoregulatory control of Skin Blood Flow occur at multiple points along the efferent arm of the reflex, including 1) diminished sympathetic outFlow, 2) altered presynaptic neurotransmitter synthesis, 3) reduced vascular responsiveness, and 4) impairments in downstream (endothelial and vascular smooth muscle) second-messenger signaling. This mechanistic review highlights some of the recent findings in the area of aging and the thermoregulatory control of Skin Blood Flow.
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Mechanisms of control of Skin Blood Flow during prolonged exercise in humans
American Journal of Physiology-Heart and Circulatory Physiology, 1993Co-Authors: Dean L. Kellogg, W. Larry Kenney, John M. Johnson, Pablo E. Pergola, Wojciech A. KosibaAbstract:Exercise in a warm environment raises internal temperature and leads to a rapid increase in Skin Blood Flow (SkBF). As exercise continues, and internal temperature approaches 38 degrees C, the rate...
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Heat stress and age: Skin Blood Flow and body temperature
Journal of Thermal Biology, 1993Co-Authors: W. Larry Kenney, George HavenithAbstract:Abstract 1. 1. The ability to increase Skin Blood Flow is an important mechanism for transferring heat from the body core to the Skin for dissipation. 2. 2. During exercise, Skin Blood Flow is typically 20–40% lower in men and women aged 55 and over (compared with 20–30 years old) at a given body core temperature. Yet criterion measures of heat tolerance (changes in core temperature, heat storage) often show minimal or no age-related alterations. From a series of studies conducted in our laboratory over the past 5 years, the following conclusions can be drawn. 3. 3. When fit healthy older subjects are matched with younger subjects of the same gender, size and body composition, V O 2max , acclimation state, and hydration level, age-related differences in Skin Blood Flow are evident. However, these differences often do not translate into “poorer” heat tolerance or higher core temperatures. 4. 4. The larger core-to-Skin thermal gradient maintained by the older individuals allows for effective heat transfer at lower Skin Blood Flows. 5. 5. Furthermore, there is an increased coefficient of variation for thermoregulatory response variables with increasing age. 6. 6. Despite differences in the mechanisms underlying thermoregulation, true thermal tolerance is less a function of chronological age than of functional capacity and physiological health status. 7. 7. While this conclusion is based primarily on cross-sectional studies, it is supported by the results of more recent studies using multiple regression analyses. 8. 8. Implicit in this conclusion is the notion that thermal tolerance, at any age, is a modifiable individual characteristic.
Yukihide Tsuchida - One of the best experts on this subject based on the ideXlab platform.
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THE EFFECT OF ANEMIA ON Skin Blood Flow IN HUMAN
Journal of dermatological science, 1995Co-Authors: Yukihide Tsuchida, Osamu Fukuda, Shin-etsu KamataAbstract:The Skin Blood Flow in the deltoid region was measured in 78 males by the Xenon 133 clearance method. A correlation was then made between age, hematocrit value, hemoglobin value and total protein determined at the time of Skin Blood Flow measurement. From the data obtained, the following conclusions could be drawn: (1) Skin Blood Flow significantly decreased with increasing age and with decreasing hematocrit and hemoglobin values; (2) Skin Blood Flow showed the closest correlation with age (P < 0.001) and a weaker correlation (P < 0.01) with hematocrit and hemoglobin; (3) total protein demonstrated a significant decrease (P < 0.01) with a decrease in hematocrit and hemoglobin values giving rise to hypoproteinemia.
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The effect of aging and arteriosclerosis on human Skin Blood Flow.
Journal of dermatological science, 1993Co-Authors: Yukihide TsuchidaAbstract:Skin Blood Flow in the deltoid region of 65 men was measured by the xenon 133 clearance method and in studying the correlation of age, total cholesterol and systolic Blood pressure to Skin Blood Flow, the following results were obtained. (1) Skin Blood Flow significantly decreased with increase in age. In calculating Skin Blood Flow at 20 and 70 years of age from the regression line between Skin Blood Flow and age, it was estimated that Skin Blood Flow at 70 years of age decreased to 40% of that at 20 years of age. (2) Skin Blood Flow significantly decreased with increase in total cholesterol and systolic Blood pressure. (3) Skin Blood Flow showed the closest correlation with age, followed by total cholesterol and systolic Blood pressure which showed a weak correlation. It is estimated from the foregoing results that as Skin Blood Flow in patients with arteriosclerosis decreases more in elderly individuals than in young persons, their wound healing is delayed.
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The correlation of Skin Blood Flow with age, total cholesterol, hematocrit, Blood pressure, and hemoglobin.
Plastic and reconstructive surgery, 1991Co-Authors: Yukihide Tsuchida, Osamu Fukuda, Shin-etsu KamataAbstract:Normal Skin Blood Flow at the deltoid region in 55 men whose ages ranged from 20 to 72 years was measured by the xenon-133 clearance method. In addition, the correlation of Skin Blood Flow with age, systolic Blood pressure, total cholesterol, hematocrit, hemoglobin, and total protein was analyzed by multiple regression analysis. The following results were obtained. Normal Skin Blood Flow was found to decrease with increase in age, total cholesterol, and systolic Blood pressure and showed a tendency to increase with elevation in hematocrit and hemoglobin values. Of the six parameters examined in the present study, the parameter that showed the strongest correlation with Skin Blood Flow at the deltoid region was age, followed in decreasing order by total cholesterol, hematocrit, systolic Blood pressure, and hemoglobin. It could therefore be concluded that age is the most reliable factor in clinically estimating Skin Blood Flow. Furthermore, inasmuch as total cholesterol, hematocrit, systolic Blood pressure and hemoglobin values also were correlated with Skin Blood Flow, these values also should be taken in account in the synthetic evaluation of Skin Blood Flow. It was Skin Blood Flow at the deltoid region that was strongly correlated with age. This was followed by systolic Blood pressure, hematocrit, and hemoglobin. Total cholesterol showed a weak correlation with age, but total protein did not demonstrate any correlation with Skin Blood Flow and age. The results of the present study show that Skin Blood Flow would be poor in the elderly and in patients with arteriosclerosis, hypertension, and anemia. Since it is suggested that the wound-healing process is delayed in such patients, utmost care should be exercised in treating their wounds.
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Age-related changes in Skin Blood Flow at four anatomic sites of the body in males studied by xenon-133.
Plastic and reconstructive surgery, 1990Co-Authors: Yukihide TsuchidaAbstract:The normal Skin Blood Flow in healthy subjects consisting of 28 males whose ages ranged from 20 to 72 years was measured by the xenon-133 clearance method at four different sites of the body to determine the presence of any age-related changes. The following results were obtained: Significant age-related changes were observed in the Skin Blood Flow of the deltoid region, anterior chest, dorsum of the hand, and dorsum of the foot. Normal Skin Blood Flow was demonstrated to be highly dependent on age and to significantly decrease with age. Average Skin Blood Flow at these four regions of those 70 years of age decreased by 30 to 40 percent when compared to that of those 20 years of age. The Skin Blood Flow at the deltoid region of healthy subjects was higher by 6.3 ml/100 gm per minute than that of patients in poor condition with cancer of the head and neck.
R. S. Reneman - One of the best experts on this subject based on the ideXlab platform.
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Skin Blood Flow abnormalities in a rat model of neuropathic pain: Result of decreased sympathetic vasoconstrictor outFlow?
Journal of The Autonomic Nervous System, 1997Co-Authors: H. A. J. M. Kurvers, R. J. Beuk, Peter J.e.h.m. Kitslaar, Dick W. Slaaf, R. S. Reneman, G J Tangelder, J G De Mey, F A Van Den Wildenberg, Michael J. JacobsAbstract:Loose ligation of a sciatic nerve in rats provokes signs and symptoms like those observed in human conditions of neuropathic pain. Some of these have been associated with sympathetic dysfunction. Since the Skin microcirculation in the rat is strongly influenced by sympathetic tone, abnormalities in Skin Blood Flow may be used as an indirect measure of sympathetic dysfunction. We measured, by means of laser Doppler Flowmetry, Skin Blood Flow at the plantar surface of the rat hind paw before and after ipsilateral loose sciatic nerve ligation. We assessed basal Skin Blood Flow as well as the vasoconstrictor response which follows cooling of the rat abdomen. The effectiveness of this response may be used as a measure of sympathetic vasoconstrictor outFlow. As compared to the values obtained before ligation (=100%): (1) the vasoconstrictor response was impaired (65%, P
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Skin Blood Flow abnormalities in a rat model of neuropathic pain: result of decreased sympathetic vasoconstrictor outFlow?
Journal of the autonomic nervous system, 1997Co-Authors: H A Kurvers, R. J. Beuk, R. S. Reneman, G J Tangelder, J G De Mey, D W Slaaf, F A Van Den Wildenberg, P J Kitslaar, M J JacobsAbstract:Loose ligation of a sciatic nerve in rats provokes signs and symptoms like those observed in human conditions of neuropathic pain. Some of these have been associated with sympathetic dysfunction. Since the Skin microcirculation in the rat is strongly influenced by sympathetic tone, abnormalities in Skin Blood Flow may be used as an indirect measure of sympathetic dysfunction. We measured, by means of laser Doppler Flowmetry, Skin Blood Flow at the plantar surface of the rat hind paw before and after ipsilateral loose sciatic nerve ligation. We assessed basal Skin Blood Flow as well as the vasoconstrictor response which follows cooling of the rat abdomen. The effectiveness of this response may be used as a measure of sympathetic vasoconstrictor outFlow. As compared to the values obtained before ligation (= 100%): (1) the vasoconstrictor response was impaired (65%, P < 0.01) from day 1 onwards, whereas (2) basal Skin Blood Flow was increased (171%; P < 0.01) from day 3 until day 5, and decreased (51%, P < 0.0001) from day 7 until day 28. At day 28, blockade of impulse propagation in the loosely ligated sciatic nerve (by means of lidocaine) did not increase the lowered level of Skin Blood Flow. These findings suggest that in the chronic construction injury model loose ligation of a sciatic nerve reduces sympathetic vasoconstrictor outFlow, which, in turn may induce supersensitivity of Skin microvessels to catecholamines.
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The spinal component to Skin Blood Flow abnormalities in reflex sympathetic dystrophy.
Archives of neurology, 1996Co-Authors: H. A. J. M. Kurvers, Michael J. Jacobs, R. J. Beuk, F. A. J. M. Van Den Wildenberg, Peter J.e.h.m. Kitslaar, Dick W. Slaaf, R. S. RenemanAbstract:Objective: To determine whether the mechanisms of reflex sympathetic dystrophy, a neuropathic pain syndrome characterized by Skin Blood Flow abnormalities associated with sympathetic vasoconstrictor and antidromic vasodilator mechanisms, are solely of peripheral origin or have an additional spinal component and act exclusively through neural or also involve humoral pathways. Patients: The 54 patients with unilateral reflex sympathetic dystrophy were divided into the following three stages according to their perception of Skin temperature in the clinically affected hand: stage I, stationary warmth sensation; stage II, intermittent warmth and cold sensation; and stage III, stationary cold sensation. Methods: Investigation of basal Skin Blood Flow and vasoconstrictive response to dependency of Skin microvessels in the clinically unaffected hand and the clinically affected hand of patients with reflex sympathetic dystrophy and the left hand of 16 control subjects. Microcirculation was investigated at the predominantly neurally controlled thermoregulatory level (Doppler laser Flowmetry) and at the predominantly humorally controlled nutritive level (capillary microscopy). Results: In the clinically unaffected hand, at the thermoregulatory level of the microcirculation: (1) basal Skin Blood Flow was increased at stage I compared with the control subjects, whereas no differences could be observed at this stage compared with the clinically affected hand; (2) the vasoconstrictive response to dependency (defined as Skin Blood Flow at heart level divided by Skin Blood Flow in the dependent position) was attenuated at stage I compared with the control subjects, whereas no differences could be observed at this stage compared with the clinically affected hand; and (3) basal Skin Blood Flow and the vasoconstrictive response to dependency did not differ from the control subjects at stages II and III. In the clinically unaffected hand, at the nutritive level, no differences could be observed at any stage of the syndrome compared with the control subjects. Conclusions: This study indicates that there is a spinal component to microcirculatory abnormalities at stage I of the reflex sympathetic dystrophy syndrome that most likely acts through neural (antidromic vasodilator) mechanisms and that may be initiated by traumatic excitation of a peripheral nerve on the clinically affected side.
Marc Rendell - One of the best experts on this subject based on the ideXlab platform.
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Skin Blood Flow abnormalities in diabetic dermopathy
Journal of the American Academy of Dermatology, 2011Co-Authors: Alexandra Brugler, Shaun L. Thompson, Scott A. Turner, Binh Ngo, Marc RendellAbstract:Background Diabetic dermopathy is the most common specific cutaneous finding in diabetes. Objective Using laser Doppler technology, we tested the hypothesis that diabetic dermopathy arises from abnormal local Skin Blood Flow. Methods We measured cutaneous Blood Flow in patients with type 1 diabetes without dermopathy and compared values with those in a control group of patients with type 1 diabetes without diabetic dermopathy and in a nondiabetic group. We measured at 3 separate sites on the pretibial area on the legs of each participant, at dermopathy lesions, and at a number of standard sites on the upper and lower extremities. Results We studied 25 patients with diabetes and diabetic dermopathy, average age 51 ± 2 years, mean duration of diabetes 28 ± 3 years. In all, 58 patients with type 1 diabetes without diabetic dermopathy served as control patients, average age 41 ± 2 years, mean duration of diabetes 23 ± 2 years. There were 67 nondiabetic control subjects, average age 47 ± 3 years. The patients with diabetic dermopathy showed a marked reduction in Skin Blood Flow at 35°C at normal-appearing Skin areas on the pretibial surface of the legs (1.1 ± 0.1 mL/min/100 g) compared with 1.7 ± 0.1 mL/min/100 g ( P = .01) in the type 1 diabetic control group and 2.1 ± 0.3 mL/min/100 g ( P Limitations Our diabetic dermopathy patients were somewhat older than the control type 1 diabetes subjects, but were of comparable age to the nondiabetic subjects. Conclusions These results suggest that patients susceptible to diabetic dermopathy have a functional abnormality in Blood Flow leading to this scarring process.
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The effect of chronic hypertension on Skin Blood Flow.
Journal of hypertension, 1996Co-Authors: Marc Rendell, Brian K. Milliken, Emily J. Banset, Mary F. Finnegan, Christopher Stanosheck, John V. TerandoAbstract:ObjectiveTo determine whether the cutaneous microvasculature of the spontaneously hypertensive rat (SHR) is affected by chronic hypertensionDesignWe used laser Doppler techniques to measure Skin Blood Flow in 22 SHR and in 22 non-hypertensive Wistar- Kyoto (WKY) rats over a 1-year time span, beginni
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The effect of aging on Skin Blood Flow in the Wistar-Kyoto rat.
Comparative biochemistry and physiology. Part A Physiology, 1995Co-Authors: Marc Rendell, Brian K. Milliken, Steven F. Mcintyre, Michele Satterlee, August J. EckermannAbstract:Abstract Using laser Doppler techniques in man, we have previously demonstrated that Skin Blood Flow decreases linearly with age. In previous work, we have shown similarities in Skin Blood Flow properties between man and the rat. Our goal was to assess a possible aging effect of Skin Blood Flow in the rat. We determined Skin Blood Flow sequentially in 13 Wistar-Kyoto rats, beginning at 3 months of age, then at 6, 12, 15 and 18 months. We measured Flow on the back, the base of the tail, the upper leg, all nutritively (NUTR) perfused sites, and on the plantar paw surface, which is perfused chiefly by arteriovenous anastomotic (AVA) capillaries. We measured Flow, microvascular volume and red Blood cell velocity at basal temperature and also heated the Skin locally to 44°C, to elicit maximal vasodilation. Skin Blood Flow declined in a linear fashion with increasing age. The decrease was in the order of 15% over 18 months and occurred at both NUTR sites and the paw. The decrease was due to reduced microvascular volume, presumably representing loss of Skin capillaries. Red Blood cell velocity was not reduced; in fact, it was significantly increased at several NUTR sites. The WKY rat provides an excellent model of aging of the Skin microvasculature. The changes we have demonstrated, while not identical to those we have previously demonstrated in man, are sufficiently similar to permit further exploration of the mechanisms of these changes.
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Decreased Skin Blood Flow early in the course of streptozotocin-induced diabetes mellitus in the rat
Diabetologia, 1993Co-Authors: Marc Rendell, S. T. Kelly, D. A. Finney, T. Luu, K. Kahler, S. F. Mcintyre, J. V. TerandoAbstract:We have previously used laser Doppler technology to demonstrate that Skin Blood Flow is reduced in Type 1 (insulin-dependent) diabetic patients. The possibility of using the Skin as an extremely accessible indicator of diabetic microvascular disease is attractive. The streptozotocin diabetic rat is an appealing potential animal model. We performed measurements of Skin Blood Flow in two rat species, nine Sprague Dawley (SD) rats and nine Wistar Kyoto (WKY) rats, observing early changes following the inception of diabetes. Four of the SD rats and five of the WKY rats were made diabetic, the rest serving as controls. There were no significant differences in Skin Blood Flow between the two rat strains. As in man, there appear to be rat Skin sites with primarily nutritive capillary supply and those with arteriovenous anastomotic predominance. The back and base of tail, both hair-covered areas, demonstrated low Flow characteristics, consistent with nutritive perfusion. In contrast, the plantar surface of the paw behaved similarly to the finger or toe pulps in man, sites of arteriovenous perfusion, with high basal Flow and a marked increment with thermal stimulation. In diabetic rats of both species, there was significantly lower Flow at the back and base of tail than in non-diabetic animals. The differences were of the order of 30–40 %. As a function of time, the decrease in Blood Flow at the base of tail parallelled the increase in glycohaemoglobin levels in the diabetic rats. In contrast, Blood Flow at the plantar surface of the paw was unchanged throughout the 3-month post-streptozotocin observation period. The decreases seen in Blood Flow were primarily due to decreases in the velocity rather than the volume component of Flow. We conclude that there is an early phase of Skin Blood Flow reduction in the diabetic rat. The reduction in Skin Blood Flow is found at nutritively perfused Skin sites but not at areas with arteriovenous anastomotic predominance.
Grant H. Simmons - One of the best experts on this subject based on the ideXlab platform.
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changes in the control of Skin Blood Flow with exercise training where do cutaneous vascular adaptations fit in
Experimental Physiology, 2011Co-Authors: Grant H. Simmons, Lacy A. Holowatz, Brett J. Wong, Larry W KenneyAbstract:Heat is the most abundant byproduct of cellular metabolism. As such, dynamic exercise in which a significant percentage of muscle mass is engaged generates thermoregulatory demands that are met in part by increases in Skin Blood Flow. Increased Skin Blood Flow during exercise adds to the demands on cardiac output and confers additional circulatory strain beyond that associated with perfusion of active muscle alone. Endurance exercise training results in a number of physiological adaptations which ultimately reduce circulatory strain and shift thermoregulatory control of Skin Blood Flow to higher levels of Blood Flow for a given core temperature. In addition, exercise training induces peripheral vascular adaptations within the cutaneous microvasculature indicative of enhanced endothelium-dependent vasomotor function. However, it is not currently clear how (or if) these local vascular adaptations contribute to the beneficial changes in thermoregulatory control of Skin Blood Flow following exercise training. The purpose of this Hot Topic Review is to synthesize the literature pertaining to exercise training-mediated changes in cutaneous microvascular reactivity and thermoregulatory control of Skin Blood Flow. In addition, we address mechanisms driving changes in cutaneous microvascular reactivity and thermoregulatory control of Skin Blood Flow, and pose the question: what (if any) is the functional role of increased cutaneous microvascular reactivity following exercise training?
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Changes in the control of Skin Blood Flow with exercise training: where do cutaneous vascular adaptations fit in?
Experimental physiology, 2011Co-Authors: Grant H. Simmons, Lacy A. Holowatz, Brett J. Wong, W. Larry KenneyAbstract:Heat is the most abundant byproduct of cellular metabolism. As such, dynamic exercise in which a significant percentage of muscle mass is engaged generates thermoregulatory demands that are met in part by increases in Skin Blood Flow. Increased Skin Blood Flow during exercise adds to the demands on cardiac output and confers additional circulatory strain beyond that associated with perfusion of active muscle alone. Endurance exercise training results in a number of physiological adaptations which ultimately reduce circulatory strain and shift thermoregulatory control of Skin Blood Flow to higher levels of Blood Flow for a given core temperature. In addition, exercise training induces peripheral vascular adaptations within the cutaneous microvasculature indicative of enhanced endothelium-dependent vasomotor function. However, it is not currently clear how (or if) these local vascular adaptations contribute to the beneficial changes in thermoregulatory control of Skin Blood Flow following exercise training. The purpose of this Hot Topic Review is to synthesize the literature pertaining to exercise training-mediated changes in cutaneous microvascular reactivity and thermoregulatory control of Skin Blood Flow. In addition, we address mechanisms driving changes in cutaneous microvascular reactivity and thermoregulatory control of Skin Blood Flow, and pose the question: what (if any) is the functional role of increased cutaneous microvascular reactivity following exercise training?
