Static and dynamic changes in carotid artery diameter in humans during and after strenuous exercise

Studinger, Péter; Lénárd, Zsuzsanna; Kovats, Zsuzsanna; Kocsis, László; Kollai, Márk

doi:10.1113/jphysiol.2003.040147

Cited by 53 publications

(56 citation statements)

References 33 publications

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“…Comparable to a previous report, 33 mechanical BRS was reduced after exercise. This study used the ␣ index for BRS assessment, however, and thus could not differentiate between mechanical G up and G down , both of which were found to decrease similarly in the present study.…”

Section: Mechanical and Neural Alterations After Exercisesupporting

confidence: 76%

Neuromechanical Features of the Cardiac Baroreflex After Exercise

et al. 2011

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Abstract-A single bout of exercise is associated with postexercise hypotension, transient decreases in autonomic function, and changes in baroreflex sensitivity. The baroreflex is less sensitive to falling blood pressure than to rising blood pressure; we characterized the cardiac baroreflex in terms of hysteresis and its mechanical and neural components. We hypothesized that hysteresis would be exacerbated postexercise because of a greater relative decrease in falling blood pressure. In 10 healthy young humans (5 men), we used bolus injections of sodium nitroprusside and phenylephrine hydrochloride to drive transient decreases and increases in blood pressure, respectively, to quantify cardiac baroreflex sensitivity to falling and rising blood pressure. This was completed before and at 10, 30, and 60 minutes after 40 minutes of cycling at 60% estimated maximal oxygen consumption. Analyses of beat-to-beat blood pressure, R-R intervals and heart rate, and carotid artery diameter were used to determine the integrated cardiac baroreflex response; this was further quantified into a mechanical component (systolic blood pressure versus carotid diameter) and a neural component (carotid diameter versus R-R interval). There were 2 principle findings: after aerobic exercise baroreflex sensitivity is reduced and hysteresis manifests, and the reduction in sensitivity to falling blood pressure is mediated by decreased mechanical and neural gains, whereas the decreased baroreflex sensitivity to rising blood pressure is mediated by a reduced mechanical gain only. We suggest that impaired neural transduction of the cardiac baroreflex, and its influence on hysteresis, plays an important role in transient autonomic dysfunction after exercise. (Hypertension. 2011;57:927-933.)Key Words: baroreflex sensitivity Ⅲ cardiac Ⅲ exercise Ⅲ postexercise hypotension Ⅲ autonomic A single bout of moderate-to-high-intensity exercise is associated with postexercise alterations in cardiac baroreflex sensitivity (BRS) and often a period of postexercise hypotension. It has been reported that 10 to 30 minutes after exercise, in both hypertensive patients and young healthy subjects, BRS is initially reduced 1-3 or unchanged, 4 as assessed using nonpharmacological 1,4 or pharmacological techniques. 2,3 Some studies have demonstrated recovery or augmentation of BRS Ͼ20 minutes postexercise cessation, 2,4,5 whereas others indicated a maintained BRS attenuation. 3 On cessation of exercise, postexercise hypotension is common, with the magnitude of change dependant on resting blood pressure (BP) and the intensity and duration of exercise; hypertension and greater intensity exercise both elicit a larger postexercise BP drop. 6,7 During this postexercise period there is altered regulation of sympathetic vascular tone or increases in vasodilator substances, or both, such that systemic vascular resistance is not restored until hours later. 7,8 Likely because of these alterations to autonomic and vascular function, there is a high incidence of syncope after exerc...

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Section: Mechanical and Neural Alterations After Exercisesupporting

confidence: 76%

Neuromechanical Features of the Cardiac Baroreflex After Exercise

et al. 2011

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“…Thus sympathetically mediated vasoconstriction may have contributed. Alternatively, Studinger et al (2003) showed that at high work intensities the elevated arterial pressure induces a strong myogenic response in the carotid smooth muscle (Olesen et al 1995). When exercise is terminated and the intraluminal distending pressure suddenly drops, the myogenic smooth muscle contraction is left unopposed, causing a transient vasoconstriction.…”

Section: Carotid Artery Stiffness Indicesmentioning

confidence: 99%

“…Myogenic vasoconstriction results in baroreceptor unloading and consequent sympathetic excitation (Studinger et al 2003). Compliance and distensibility in children and adults decreased following exercise as both coefficients are largely influenced by local pressure (denominator).…”

Section: Carotid Artery Stiffness Indicesmentioning

confidence: 99%

The acute effect of maximal exercise on central and peripheral arterial stiffness indices and hemodynamics in children and adults

Melo

Fernhall²,

Santos

et al. 2016

Appl. Physiol. Nutr. Metab.

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This study compared the effects of a bout of maximal running exercise on arterial stiffness in children and adults. Right carotid blood pressure and artery stiffness indices measured by pulse wave velocity (PWV), compliance and distensibility coefficients, stiffness index α and β (echo-tracking), contralateral carotid blood pressure, and upper and lower limb and central/aortic PWV (applanation tonometry) were taken at rest and 10 min after a bout of maximal treadmill running in 34 children (7.38 ± 0.38 years) and 45 young adults (25.22 ± 0.91 years) having similar aerobic potential. Two-by-two repeated measures analysis of variance and analysis of covariance were used to detect differences with exercise between groups. Carotid pulse pressure (PP; η2 = 0.394) increased more in adults after exercise (p < 0.05). Compliance (η2 = 0.385) decreased in particular in adults and in those with high changes in distending pressure, similarly to stiffness index α and β. Carotid PWV increased more in adults and was related to local changes in PP but not mean arterial pressure (MAP). Stiffness in the lower limbs decreased (η2 = 0.115) but apparently only in those with small MAP changes (η2 = 0.111). No significant exercise or group interaction effects were found when variables were adjusted to height. An acute bout of maximal exercise can alter arterial stiffness and hemodynamics in the carotid artery and within the active muscle beds. Arterial stiffness and hemodynamic response to metabolic demands during exercise in children simply reflect their smaller body size and may not indicate a particular physiological difference compared with adults.

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“…5,7,8,10,13). In more realistic analyses, the viscoelastic behavior of arterial walls has been studied by many researchers (4,10,12,20,21,23,24,27,29). To reduce the mathematical complexity, the theory of quasi-linear viscoelasticity (10) has been applied to arteries and other living tissues (e.g., Refs.…”

mentioning

confidence: 99%

Viscoelasticity reduces the dynamic stresses and strains in the vessel wall: implications for vessel fatigue

Zhang

Liu²,

Kassab³

2007

American Journal of Physiology-Heart and Circulatory Physiology

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Zhang W, Liu Y, Kassab GS. Viscoelasticity reduces the dynamic stresses and strains in the vessel wall: implications for vessel fatigue. Am J Physiol Heart Circ Physiol 293: H2355-H2360, 2007. First published June 29, 2007; doi:10.1152/ajpheart.00423.2007.-The mechanical behavior of blood vessels is known to be viscoelastic rather than elastic. The functional role of viscoelasticity, however, has remained largely unclear. The hypothesis of this study is that viscoelasticity reduces the stresses and strains in the vessel wall, which may have a significant impact on the fatigue life of the blood vessel wall. To verify the hypothesis, the pulsatile stress in rabbit thoracic artery at physiological loading condition was investigated with a quasi-linear viscoelastic model, where the normalized stress relaxation function is assumed to be isotropic, while the stress-strain relationship is anisotropic and nonlinear. The artery was subjected to the same boundary condition, and the mechanical equilibrium equation was solved for both the viscoelastic and an elastic (which has a constant relaxation function) model. Numerical results show that, compared with purely elastic response, the viscoelastic property of arteries reduces the magnitudes and temporal variations of circumferential stress and strain. The radial wall movement is also reduced due to viscoelasticity. These findings imply that viscoelasticity may be beneficial for the fatigue life of blood vessels, which undergo millions of cyclic mechanical loadings each year of life.artery; cyclic loading; fatigue life; viscoelastic BIOLOGICAL SOFT TISSUES ARE known to have highly nonlinear stress-strain relations, strongly anisotropic mechanical properties, and significant viscoelastic features (10). Blood vessels are typical soft tissues, and their mechanical behavior is imperative for understanding vascular processes under physiological and pathological conditions. The pseudoelastic formulation (i.e., loading and unloading follow different elastic stressstrain curves) has been widely utilized to investigate salient mechanical characteristics of blood vessels (e.g., Refs. 5,7,8,10,13). In more realistic analyses, the viscoelastic behavior of arterial walls has been studied by many researchers (4,10,12,20,21,23,24,27,29). To reduce the mathematical complexity, the theory of quasi-linear viscoelasticity (10) has been applied to arteries and other living tissues (e.g., Refs. 3,6,11,15,26). One known merit of viscoelasticity in blood vessels is to reduce the wall stress and strain during a sudden increase of mechanical loading, such as in acute hypertension (1). Although this is an interesting protective acute mechanism, the functional role of viscoelasticity in blood vessels and other biological tissues has not been fully understood.From a mechanical point of view, the energy dissipation due to viscoelasticity may produce heat to maintain isothermal conditions in tissues, and the force-deformation hysteresis loop (or phase delay between stress and strain) caused by internal ...

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Static and dynamic changes in carotid artery diameter in humans during and after strenuous exercise

Cited by 53 publications

References 33 publications

Neuromechanical Features of the Cardiac Baroreflex After Exercise

Neuromechanical Features of the Cardiac Baroreflex After Exercise

The acute effect of maximal exercise on central and peripheral arterial stiffness indices and hemodynamics in children and adults

Viscoelasticity reduces the dynamic stresses and strains in the vessel wall: implications for vessel fatigue

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