Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 22
Filtrar
1.
J Appl Physiol (1985) ; 120(4): 416-25, 2016 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-26607249

RESUMO

Insufficient nitric oxide (NO) bioavailability plays an important role in endothelial dysfunction and arterial stiffening with aging. Supplementation with sodium nitrite, a precursor of NO, ameliorates age-related vascular endothelial dysfunction and arterial stiffness in mice, but effects on humans, including the metabolic pathways altered, are unknown. The purpose of this study was to determine the safety, feasibility, and efficacy of oral sodium nitrite supplementation for improving vascular function in middle-aged and older adults and to identify related circulating metabolites. Ten weeks of sodium nitrite (80 or 160 mg/day, capsules, TheraVasc; randomized, placebo control, double blind) increased plasma nitrite acutely (5- to 15-fold, P < 0.001 vs. placebo) and chronically (P < 0.10) and was well tolerated without symptomatic hypotension or clinically relevant elevations in blood methemoglobin. Endothelial function, measured by brachial artery flow-mediated dilation, increased 45-60% vs. baseline (P < 0.10) without changes in body mass or blood lipids. Measures of carotid artery elasticity (ultrasound and applanation tonometry) improved (decreased ß-stiffness index, increased cross-sectional compliance, P < 0.05) without changes in brachial or carotid artery blood pressure. Aortic pulse wave velocity was unchanged. Nitrite-induced changes in vascular measures were significantly related to 11 plasma metabolites identified by untargeted analysis. Baseline abundance of multiple metabolites, including glycerophospholipids and fatty acyls, predicted vascular changes with nitrite. This study provides evidence that sodium nitrite supplementation is well tolerated, increases plasma nitrite concentrations, improves endothelial function, and lessens carotid artery stiffening in middle-aged and older adults, perhaps by altering multiple metabolic pathways, thereby warranting a larger clinical trial.


Assuntos
Envelhecimento/efeitos dos fármacos , Aorta/efeitos dos fármacos , Artérias Carótidas/efeitos dos fármacos , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Nitrito de Sódio/farmacologia , Idoso , Envelhecimento/metabolismo , Aorta/metabolismo , Pressão Sanguínea/efeitos dos fármacos , Índice de Massa Corporal , Artéria Braquial/efeitos dos fármacos , Artéria Braquial/metabolismo , Artérias Carótidas/metabolismo , Suplementos Nutricionais , Método Duplo-Cego , Elasticidade/efeitos dos fármacos , Feminino , Humanos , Masculino , Metemoglobina/metabolismo , Pessoa de Meia-Idade , Óxido Nítrico/metabolismo , Análise de Onda de Pulso/métodos , Rigidez Vascular/efeitos dos fármacos , Vasodilatação/efeitos dos fármacos
2.
Aging (Albany NY) ; 7(11): 1004-21, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26626856

RESUMO

Advancing age is associated with reductions in nitric oxide bioavailability and changes in metabolic activity, which are implicated in declines in motor and cognitive function. In preclinical models, sodium nitrite supplementation (SN) increases plasma nitrite and improves motor function, whereas other nitric oxide-boosting agents improve cognitive function. This pilot study was designed to translate these findings to middle-aged and older (MA/O) humans to provide proof-of-concept support for larger trials. SN (10 weeks, 80 to 160 mg/day capsules, TheraVasc, Inc.) acutely and chronically increased plasma nitrite and improved performance on measures of motor and cognitive outcomes (all p<0.05 or better) in healthy MA/O adults (62 ± 7 years). Untargeted metabolomics analysis revealed that SN significantly altered 33 (160 mg/day) to 45 (80 mg/day) different metabolites, 13 of which were related to changes in functional outcomes; baseline concentrations of 99 different metabolites predicted functional improvements with SN. This pilot study provides the first evidence that SN improves aspects of motor and cognitive function in healthy MA/O adults, and that these improvements are associated with, and predicted by, the plasma metabolome. Our findings provide the necessary support for larger clinical trials on this promising pharmacological strategy for preserving physiological function with aging.


Assuntos
Cognição/efeitos dos fármacos , Atividade Motora/efeitos dos fármacos , Nitrito de Sódio/administração & dosagem , Idoso , Suplementos Nutricionais , Feminino , Humanos , Masculino , Metaboloma , Pessoa de Meia-Idade , Projetos Piloto , Nitrito de Sódio/sangue
3.
J Appl Physiol (1985) ; 116(5): 463-77, 2014 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-24408999

RESUMO

Aging is the major risk factor for cardiovascular diseases (CVD). This is attributable primarily to adverse changes in arteries, notably, increases in large elastic artery stiffness and endothelial dysfunction mediated by inadequate concentrations of the vascular-protective molecule, nitric oxide (NO), and higher levels of oxidative stress and inflammation. Inorganic nitrite is a promising precursor molecule for augmenting circulating and tissue NO bioavailability because it requires only a one-step reduction to NO. Nitrite also acts as an independent signaling molecule, exerting many of the effects previously attributed to NO. Results of recent studies indicate that nitrite may be effective in the treatment of vascular aging. In old mice, short-term oral sodium nitrite supplementation reduces aortic pulse wave velocity, the gold-standard measure of large elastic artery stiffness, and ameliorates endothelial dysfunction, as indicated by normalization of NO-mediated endothelium-dependent dilation. These improvements in age-related vascular dysfunction with nitrite are mediated by reductions in oxidative stress and inflammation, and may be linked to increases in mitochondrial biogenesis and health. Increasing nitrite levels via dietary intake of nitrate appears to have similarly beneficial effects in many of the same physiological and clinical settings. Several clinical trials are being performed to determine the broad therapeutic potential of increasing nitrite bioavailability on human health and disease, including studies related to vascular aging. In summary, inorganic nitrite, as well as dietary nitrate supplementation, represents a promising therapy for treatment of arterial aging and prevention of age-associated CVD in humans.


Assuntos
Envelhecimento/efeitos dos fármacos , Artérias/efeitos dos fármacos , Artérias/crescimento & desenvolvimento , Suplementos Nutricionais , Nitritos/uso terapêutico , Animais , Cardiotônicos/farmacologia , Doenças Cardiovasculares/fisiopatologia , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/fisiologia , Humanos , Infusões Intravenosas , Camundongos , Nitratos/fisiologia , Óxido Nítrico/fisiologia , Fatores de Risco , Nitrito de Sódio/administração & dosagem , Nitrito de Sódio/farmacologia , Rigidez Vascular/fisiologia
5.
Clin Sci (Lond) ; 124(5): 325-31, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23025811

RESUMO

In the present study, we tested the hypothesis that age-associated vascular endothelial dysfunction is exacerbated by IFG (impaired fasting plasma glucose) and that regular aerobic exercise prevents this effect. Data were analysed from a cohort of 131 non-smoking men and women without overt clinical disease. Compared with young adult controls (age=24±1 years, n=29; values are means±S.E.M.), brachial artery FMD (flow-mediated dilation), a measure of conduit artery EDD (endothelium-dependent dilation), was 33% lower [7.93±0.33 against 5.27±0.37%Δ (% change), P<0.05] in MA/O (middle-aged/older) adults with NFG (normal fasting plasma glucose) (≤99 mg/dl, 62±1 years, n=35). In MA/O adults with IFG (100-125 mg/dl, 64±1 years, n=28), FMD was 30% lower (3.37±0.35%Δ) than in their peers with NFG and 58% lower than young controls (P<0.05). Brachial artery FMD was greater (6.38±0.35%Δ) in MA/O adults with NFG who regularly performed aerobic exercise (>45 min/day for ≥5 days/week, 62±1 years, n=23) compared with their non-exercising peers and only slightly less than young controls (P<0.05). Most importantly, FMD was completely preserved in MA/O adults with IFG who regularly performed aerobic exercise (6.99±0.69%Δ, 65±1 years, n=16). In the pooled sample, fasting plasma glucose was inversely related to FMD (r=-0.42, P<0.01) and was the strongest independent predictor of FMD (R(2)=0.32). Group differences in FMD were not affected by other subject characteristics or brachial artery properties, including brachial artery dilation to sublingual NTG (nitroglycerine, i.e. endothelium-independent dilation). IFG exacerbates age-associated vascular endothelial dysfunction and this adverse effect is completely prevented in MA/O adults who regularly perform aerobic exercise.


Assuntos
Envelhecimento/fisiologia , Glicemia/metabolismo , Doenças Cardiovasculares/prevenção & controle , Doenças Cardiovasculares/fisiopatologia , Endotélio Vascular/fisiopatologia , Exercício Físico/fisiologia , Adolescente , Adulto , Idoso , Artéria Braquial/fisiologia , Doenças Cardiovasculares/metabolismo , Estudos de Coortes , Bases de Dados Factuais/estatística & dados numéricos , Endotélio Vascular/metabolismo , Jejum/fisiologia , Feminino , Humanos , Insulina/sangue , Masculino , Pessoa de Meia-Idade , Aptidão Física/fisiologia , Estado Pré-Diabético/metabolismo , Estado Pré-Diabético/fisiopatologia , Estado Pré-Diabético/prevenção & controle , Fluxo Sanguíneo Regional/fisiologia , Adulto Jovem
6.
Vasc Med ; 17(4): 231-4, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22848085

RESUMO

Flow-mediated dilation (FMD) is a non-invasive index of endothelial function. In an attempt to standardize FMD for shear stimulus, shear rate (velocity/diameter), rather than shear stress (viscosity*velocity/diameter), is commonly used as a surrogate measure, although it is limited by individual differences in blood viscosity. The purpose of this study was to determine the contribution of whole blood viscosity to FMD and other key measures of vascular function. Blood viscosity, FMD, carotid artery compliance, and carotid-femoral pulse wave velocity (cfPWV) were measured in 98 apparently healthy adults varying widely in age (18-63 years). Whole blood viscosity was not significantly correlated with FMD, cfPWV, or carotid artery compliance. Shear rate was a stronger correlate with FMD than shear stress that takes blood viscosity into account (r = 0.43 vs 0.28). No significant differences were observed between whole blood viscosity and traditional risk factors for cardiovascular disease. Age was positively correlated with cfPWV (r = 0.65, p < 0.001) and negatively correlated with FMD (r = -0.24, p < 0.05) and carotid artery compliance (r = -0.45, p < 0.01). Controlling for viscosity did not reduce the strength of these relations. These results indicate that whole blood viscosity does not significantly impact measures of vascular function and suggests that the common practice to use shear rate, rather than shear stress, in the adjustment of FMD is valid.


Assuntos
Viscosidade Sanguínea/fisiologia , Artéria Braquial/fisiologia , Fluxo Sanguíneo Regional/fisiologia , Rigidez Vascular/fisiologia , Adolescente , Adulto , Velocidade do Fluxo Sanguíneo/fisiologia , Artérias Carótidas/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise de Onda de Pulso , Fatores de Risco , Estresse Mecânico , Vasodilatação/fisiologia , Adulto Jovem
7.
Am J Hypertens ; 25(10): 1050-4, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22673017

RESUMO

BACKGROUND: We performed a pilot study to test the hypothesis that acute oral ingestion of tetrahydrobiopterin (BH(4)), a key cofactor modulating vascular nitric oxide (NO) synthase activity, improves large elastic artery stiffness with aging in men. METHODS: Healthy older (63 ± 2 years; n = 8) and young (age 25 ± 1 years; n = 6) men were studied 3 h after ingestion of BH(4) (10 mg·kg(-1) body weight) or placebo on separate days in a randomized, placebo-controlled, double-blind study. RESULTS: Baseline carotid artery compliance was 37% lower (0.17 ± 0.02 vs. 0.22 ± 0.02 mm/mm Hg·10(-1)) and ß-stiffness was 42% higher (7.3 ± 1.1 vs. 4.2 ± 0.5 AU) in the older men (both P < 0.05). BH(4) ingestion markedly increased circulating BH(4) concentrations in both groups (17-19-fold, P < 0.05), but increased compliance (+39% to 0.23 ± 0.02 mm/mm Hg·10(-1), P < 0.01) and decreased ß-stiffness index (-27% to 5.3 ± 0.7 AU, P < 0.01) only in the older men. BH(4) also reduced carotid systolic blood pressure (SBP) in the older men (P < 0.05). CONCLUSIONS: These preliminary results support the possibility that limited BH(4) bioavailability contributes to impaired carotid artery compliance in healthy older men. Further studies are needed to determine if increasing BH(4) bioavailability though oral BH(4) supplementation may have therapeutic efficacy for improving large elastic artery compliance and reducing central SBP with aging.


Assuntos
Biopterinas/análogos & derivados , Artérias Carótidas/fisiologia , Adulto , Idoso , Biopterinas/farmacologia , Artérias Carótidas/efeitos dos fármacos , Complacência (Medida de Distensibilidade)/efeitos dos fármacos , Suplementos Nutricionais , Método Duplo-Cego , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Rigidez Vascular/efeitos dos fármacos
8.
Exp Physiol ; 97(3): 305-10, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22266948

RESUMO

The demographics of ageing are changing dramatically such that there will be many more older adults in the near future. This setting is projected to produce a new 'boomer-driven' epidemic of physiological dysfunction, disability and risk of chronic degenerative disorders, including cardiovascular diseases. Standing out against this dreary biomedical forecast are Masters athletes, a group of middle-aged and older adults who engage in regular vigorous physical training and competitive sport. Compared with their sedentary/less active (untrained) peers, Masters athletes who perform endurance training-based activities demonstrate a more favourable arterial function-structure phenotype, including lower large elastic artery stiffness, enhanced vascular endothelial function and less arterial wall hypertrophy. As such, they may represent an exemplary model of healthy or 'successful' vascular ageing. In contrast, Masters athletes engaged primarily/exclusively in intensive resistance training exhibit less favourable arterial function-structure than their endurance-trained peers and, in some instances, untrained adults. These different arterial properties are probably explained in large part by the different intravascular mechanical forces generated during endurance versus resistance exercise-related training activities. The more favourable arterial function-structure profile of Masters endurance athletes may contribute to their low risk of clinical cardiovascular diseases.


Assuntos
Envelhecimento/fisiologia , Atletas , Vasos Sanguíneos/fisiologia , Desempenho Atlético , Fenômenos Biomecânicos , Doenças Cardiovasculares/epidemiologia , Elasticidade/fisiologia , Endotélio Vascular/fisiologia , Humanos , Fatores de Risco
9.
Atherosclerosis ; 219(1): 191-3, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21840524

RESUMO

Resistance exercise involves muscular contractions that can render downstream tissues ischemic and may precondition the vasculature against ischemia-reperfusion (IR) injury, but it is unknown if habitual resistance exercise protects against IR injury in humans. We determined the magnitude and recovery from endothelial IR injury induced by forearm occlusion in 22 healthy young sedentary and resistance-trained adults. After IR injury, brachial artery flow-mediated dilation (FMD) significantly decreased by 36% in sedentary, but not resistance-trained subjects and fully recovered within 45 min. Though HDL-cholesterol, handgrip strength and systolic blood pressure were significantly associated with FMD 15 min after IR injury, the change in FMD from before to 15 min after IR injury was not associated with any subject characteristics. These results are consistent with the notion that habitual resistance exercise may protect against endothelial IR injury in young adults, presumably through effects analogous to ischemic preconditioning.


Assuntos
Exercício Físico/fisiologia , Traumatismo por Reperfusão/fisiopatologia , Adulto , Artéria Braquial/fisiopatologia , Feminino , Antebraço/irrigação sanguínea , Força da Mão , Humanos , Precondicionamento Isquêmico/métodos , Masculino , Traumatismo por Reperfusão/prevenção & controle , Vasodilatação/fisiologia , Adulto Jovem
10.
Am J Physiol Heart Circ Physiol ; 300(3): H813-9, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21239631

RESUMO

Advancing age is a major risk factor for coronary artery disease. Endothelial dysfunction accompanied by increased oxidative stress and inflammation with aging may predispose older arteries to greater ischemia-reperfusion (I/R) injury. Because coronary artery ischemia cannot be induced safely, the effects of age and habitual endurance exercise on endothelial I/R injury have not been determined in humans. Using the brachial artery as a surrogate model of the coronary arteries, endothelial function, assessed by brachial artery flow-mediated dilation (FMD), was measured before and after 20 min of continuous forearm occlusion in young sedentary (n = 10, 24 ± 2 yr) and middle-aged (n = 9, 48 ± 2 yr) sedentary adults to gain insight into the effects of primary aging on endothelial I/R injury. Young (n = 9, 25 ± 1 yr) and middle-aged endurance-trained (n = 9, 50 ± 2 yr) adults were also studied to determine whether habitual exercise provides protection from I/R injury. Fifteen minutes after ischemic injury, FMD decreased significantly by 37% in young sedentary, 35% in young endurance-trained, 68% in middle-aged sedentary, and 50% in middle-aged endurance-trained subjects. FMD returned to baseline levels within 30 min in young sedentary and endurance-trained subjects but remained depressed in middle-aged sedentary and endurance-trained subjects. Circulating markers of antioxidant capacity and inflammation were not related to FMD. In conclusion, advancing age is associated with a greater magnitude and delayed recovery from endothelial I/R injury in humans. Habitual endurance exercise may provide partial protection to the endothelium against this form of I/R injury with advancing age.


Assuntos
Envelhecimento/fisiologia , Artéria Braquial/fisiopatologia , Exercício Físico/fisiologia , Traumatismo por Reperfusão/fisiopatologia , Antioxidantes/fisiologia , Vasos Coronários/fisiopatologia , Endotélio Vascular/fisiopatologia , Feminino , Antebraço/irrigação sanguínea , Antebraço/fisiopatologia , Hábitos , Humanos , Mediadores da Inflamação/sangue , Mediadores da Inflamação/fisiologia , Masculino , Pessoa de Meia-Idade , Consumo de Oxigênio/fisiologia , Resistência Física/fisiologia , Comportamento Sedentário , Vasodilatação/fisiologia
11.
Clin Physiol Funct Imaging ; 31(1): 66-72, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20880350

RESUMO

Monitoring alterations in fingertip temperature during ischaemia and the subsequent hyperaemia provides a novel way of studying microvascular reactivity. The relations between parameters characterizing blood perfusion and the thermal response of fingertips were studied using experimental and theoretical approaches. During the experimental protocol, two brachial artery occlusion tests were conducted in 12 healthy volunteers, and fingertip temperature, heat flux and skin perfusion using laser Doppler flowmetry (LDF) were measured. The temperature curves provide a smooth and robust response that is able to capture occlusion and reperfusion. The temperature fall during occlusion as well as the maximum temperature recorded depended linearly on the initial temperature. The magnitude of the LDF signal was associated with local tissue temperature and followed an exponential response. Heat flux measurements demonstrated rapid changes and followed variations in blood perfusion closely. The time points at which the heat flux reached its maximum corresponded to the time at which the fingertip temperature curves showed an inflection point after cuff release. The time required for the fingertip temperature to arrive at the maximum temperature was greater than the time to peak for the heat flux signal, which was greater than the LDF signal to reach a maximum. The time lag between these signals was a function of the finger size and finger temperature at the moment reperfusion restarted. Our present results indicate that finger temperature, heat flux and perfusion display varying rates of recovery following ischaemic stimuli and that differential responses are associated with the initial finger temperature.


Assuntos
Dedos/irrigação sanguínea , Fluxometria por Laser-Doppler/métodos , Temperatura Cutânea/fisiologia , Pele/irrigação sanguínea , Adulto , Temperatura Corporal/fisiologia , Feminino , Humanos , Hiperemia/fisiopatologia , Isquemia/fisiopatologia , Masculino , Microvasos/fisiopatologia , Condutividade Térmica
13.
J Appl Physiol (1985) ; 105(2): 427-32, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18483158

RESUMO

The clinical importance of vascular reactivity as an early marker of atherosclerosis has been well established, and a number of established and emerging techniques have been employed to provide measurements of peripheral vascular reactivity. However, relations between these methodologies are unclear as each technique evaluates different physiological aspects related to micro- and macrovascular reactive hyperemia. To address this question, a total of 40 apparently healthy normotensive adults, 19-68 yr old, underwent 5 min of forearm suprasystolic cuff-induced ischemia followed by postischemic measurements. Measurements of vascular reactivity included 1) flow-mediated dilatation (FMD), 2) changes in pulse wave velocity between the brachial and radial artery (DeltaPWV), 3) hyperemic shear stress, 4) reactive hyperemic flow, 5) reactive hyperemia index (RHI) assessed by fingertip arterial tonometry, 6) fingertip temperature rebound (TR), and 7) skin reactive hyperemia. FMD was significantly and positively associated with RHI (r=0.47) and TR (r=0.45) (both P<0.01) but not with reactive hyperemic flow or hyperemic shear stress. There was no correlation between two measures of macrovascular reactivity (FMD and DeltaPWV). Skin reactive hyperemia was significantly associated with RHI (r=0.55) and reactive hyperemic flow (r=0.35) (both P<0.05). There was a significant association between reactive hyperemia and RHI (r=0.30; P<0.05). In more than 75% of cases, vascular reactivity measures were not significantly associated. We concluded that associations among different measures of peripheral micro- and macrovascular reactivity were modest at best. These results suggest that different physiological mechanisms may be involved in changing different measures of vascular reactivity.


Assuntos
Vasos Sanguíneos/fisiopatologia , Isquemia/diagnóstico , Adulto , Idoso , Aterosclerose/fisiopatologia , Artéria Braquial/patologia , Artéria Braquial/fisiopatologia , Capilares/fisiopatologia , Doença Crônica , Feminino , Dedos/irrigação sanguínea , Humanos , Hiperemia/diagnóstico , Hiperemia/fisiopatologia , Isquemia/fisiopatologia , Masculino , Pessoa de Meia-Idade , Pletismografia , Artéria Radial/patologia , Artéria Radial/fisiopatologia , Fatores de Risco , Pele/irrigação sanguínea , Temperatura Cutânea/fisiologia , Vasodilatação/fisiologia
14.
Eur J Cardiovasc Prev Rehabil ; 15(2): 149-55, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18391640

RESUMO

BACKGROUND: Contrary to aerobic exercise, strength training (ST) is associated with decreased central arterial compliance in young men. It is unknown whether ST, with or without concurrent endurance training, would have a similar effect in older adults with reduced baseline arterial compliance. OBJECTIVE: The primary aim of this study was to determine the effect of a ST program on central arterial compliance in middle-aged and older adults. DESIGN: Randomized, controlled intervention study in which 37 healthy, sedentary men and women (52+/-2 years) performed 13 weeks of ST (n=13), ST+aerobic exercise (n=12) or stretching exercises as a control group (n=12). METHODS: Participants were rigorously screened for cardiovascular disease and underwent pre-post testing for carotid arterial compliance (via simultaneous ultrasound and applanation tonometry), carotid-femoral pulse wave velocity, plasma endothelin-1 and angiotensin II concentrations and carotid artery vasoreactivity (cold pressor test). RESULTS: ST performed alone, or in conjunction with aerobic exercise, improved maximal muscle strength and increased total lean body mass (both P<0.01). No significant changes were observed in carotid artery compliance or carotid-femoral pulse wave velocity following ST or ST+aerobic exercise. Carotid artery compliance increased significantly (23%) following stretching which may be attributed to a reduction in carotid pulse pressure. No significant changes were observed in plasma vasoconstrictor hormones or carotid artery vasoreactivity following the interventions. CONCLUSION: Thirteen weeks of moderate ST two or three times per week does not reduce central arterial compliance in middle-aged and older adults.


Assuntos
Envelhecimento , Artérias Carótidas/fisiologia , Exercício Físico/fisiologia , Força Muscular , Músculo Esquelético/fisiologia , Fatores Etários , Angiotensina II/sangue , Pressão Sanguínea , Índice de Massa Corporal , Artérias Carótidas/diagnóstico por imagem , Temperatura Baixa , Complacência (Medida de Distensibilidade) , Endotelina-1/sangue , Feminino , Humanos , Masculino , Manometria , Pessoa de Meia-Idade , Consumo de Oxigênio , Fatores de Tempo , Ultrassonografia , Vasodilatação
15.
J Appl Physiol (1985) ; 101(5): 1351-5, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16840576

RESUMO

Age-related reductions in basal limb blood flow and vascular conductance are associated with the metabolic syndrome, functional impairments, and osteoporosis. We tested the hypothesis that a strength training program would increase basal femoral blood flow in aging adults. Twenty-six sedentary but healthy middle-aged and older subjects were randomly assigned to either a whole body strength training intervention group (52 +/- 2 yr, 3 men, 10 women) who underwent three supervised resistance training sessions per week for 13 wk or a control group (53 +/- 2 yr, 4 men, 9 women) who participated in a supervised stretching program. At baseline, there were no significant differences in blood pressure, cardiac output, basal femoral blood flow (via Doppler ultrasound), vascular conductance, and vascular resistance between the two groups. The strength training group increased maximal strength in all the major muscle groups tested (P < 0.05). Whole body lean body mass increased (P < 0.05) with strength training, but leg fat-free mass did not. Basal femoral blood flow and vascular conductance increased by 55-60% after strength training (both P < 0.05). No such changes were observed in the control group. In both groups, there were no significant changes in brachial blood pressure, plasma endothelin-1 and angiotensin II concentrations, femoral artery wall thickness, cardiac output, and systemic vascular resistance. Our results indicate that short-term strength training increases basal femoral blood flow and vascular conductance in healthy middle-aged and older adults.


Assuntos
Envelhecimento/fisiologia , Educação Física e Treinamento , Fluxo Sanguíneo Regional/fisiologia , Resistência Vascular/fisiologia , Levantamento de Peso/fisiologia , Velocidade do Fluxo Sanguíneo/fisiologia , Pressão Sanguínea/fisiologia , Exercício Físico/fisiologia , Feminino , Artéria Femoral/diagnóstico por imagem , Artéria Femoral/fisiologia , Humanos , Perna (Membro)/irrigação sanguínea , Masculino , Pessoa de Meia-Idade , Força Muscular/fisiologia , Ultrassonografia
16.
Atherosclerosis ; 185(1): 201-5, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16046216

RESUMO

Acute and chronic smoking reduces peripheral blood flow and shear stress, contributing to the increased incidence of peripheral arterial disease in smokers. Currently, it is not known whether physical activity status influences peripheral blood flow among chronic smokers. Blood flow was measured using Doppler ultrasound on the common femoral artery in nine young otherwise healthy sedentary smokers (eight males/one female) and nine physically-active smokers (six males/three females). Physically-active smokers performed strenuous exercise 4.4 times/week for 8 h/week. No significant differences in body fat, blood pressure, and total cholesterol were observed between groups. Basal femoral artery blood flow was approximately 50% higher in physically-active smokers compared with sedentary smokers (259+/-108 ml min(-1) versus 173+/-47 ml min(-1), P<0.05). The higher basal femoral artery blood flow in physically-active smokers compared with sedentary smokers was associated with a 47% higher femoral artery vascular conductance (2.99+/-1.2 U versus 2.03+/-0.5 U, P<0.05) and a 39% lower vascular resistance (0.38+/-0.13 U versus 0.53+/-0.15 U, P<0.05). Cardiac output, systemic vascular resistance, femoral intima-media thickness, and plasma norepinephrine concentration were not different between the groups. We concluded that smokers who habitually perform physical activity demonstrate greater levels of peripheral blood flow and peripheral vascular conductance. The findings from the present cross-sectional study suggest that chronic smokers may be able to negate, at least in part, the adverse effects of chronic smoking on the peripheral vasculature by performing regular physical activity.


Assuntos
Velocidade do Fluxo Sanguíneo/fisiologia , Exercício Físico/fisiologia , Artéria Femoral/fisiopatologia , Doenças Vasculares Periféricas/fisiopatologia , Fumar/fisiopatologia , Adulto , Débito Cardíaco , Estudos Transversais , Progressão da Doença , Feminino , Artéria Femoral/diagnóstico por imagem , Seguimentos , Humanos , Masculino , Doenças Vasculares Periféricas/diagnóstico por imagem , Doenças Vasculares Periféricas/etiologia , Fatores de Risco , Fumar/efeitos adversos , Ultrassonografia
17.
Am J Physiol Heart Circ Physiol ; 290(4): H1596-600, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16284225

RESUMO

Regular endurance exercise increases central arterial compliance, whereas resistance training decreases it. It is not known how the vasculature adapts to a combination of endurance and resistance training. Rowing is unique, because its training encompasses endurance- and strength-training components. We used a cross-sectional study design to determine arterial compliance of 15 healthy, habitual rowers [50 +/- 9 (SD) yr, 11 men and 4 women] and 15 sedentary controls (52 +/- 8 yr, 10 men and 5 women). Rowers had been training 5.4 +/- 1.2 days/wk for 5.7 +/- 4.0 yr. The two groups were matched for age, body composition, blood pressure, and metabolic risk factors. Central arterial compliance (simultaneous ultrasound and applanation tonometry on the common carotid artery) was higher (P < 0.001) and carotid beta-stiffness index was lower (P < 0.001) in rowers than in sedentary controls. There were no group differences for measures of peripheral (femoral) arterial stiffness. The higher central arterial compliance in rowers was associated with a greater cardiovagal baroreflex sensitivity, as estimated during a Valsalva maneuver (r = 0.54, P < 0.005). In conclusion, regular rowing exercise in middle-aged and older adults is associated with a favorable effect on the elastic properties of the central arteries. Our results suggest that simultaneously performed endurance training may negate the stiffening effects of strength training.


Assuntos
Envelhecimento/fisiologia , Artéria Carótida Primitiva/fisiologia , Exercício Físico/fisiologia , Resistência Física/fisiologia , Aptidão Física/fisiologia , Esportes/fisiologia , Adaptação Fisiológica/fisiologia , Adulto , Aerobiose/fisiologia , Idoso , Elasticidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Navios , Resistência Vascular/fisiologia
18.
Am J Hypertens ; 18(7): 930-4, 2005 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16053989

RESUMO

BACKGROUND: Cross-sectional studies reported that chronic resistance training is associated with arterial stiffening in men. These findings are in marked contrast to those found with aerobic exercise and may have important clinical relevance with regard to cardiovascular disease risk. However, the effect of resistance training on arterial stiffness has not been confirmed by interventional studies nor has this relation been investigated in women. METHODS: To determine whether a strength training program increases regional and central arterial stiffness in women, 23 healthy young women (29+/-1 years; mean+/-SD) participated in a high-intensity strength and power training program for 11 weeks. Ten other women (27+/-2 years) served as time controls. RESULTS: In the intervention group, one repetition maximal strength increased 12% to 17% (P<.0001), and leg fat-free mass (via DEXA) increased significantly. Brachial blood pressure (BP) and fasting plasma lipid and lipoprotein concentrations did not change across the 11 weeks. Carotid augmentation index, a measure of arterial wave reflection and arterial stiffness, increased from -8%+/-13% to 1%+/-18% (P<.05), and carotid-femoral pulse wave velocity increased (791+/-88 v 833+/-96 cm/sec; P<.05). There were no changes in femoral-ankle pulse wave velocity, a segmental measure of peripheral arterial stiffness. CONCLUSIONS: We concluded that a high-intensity resistance training program increases arterial stiffness and wave reflection in young healthy women. Our present interventional results are consistent with the previous cross-sectional studies in men in which high-intensity strength training is associated with arterial stiffening.


Assuntos
Artérias/fisiologia , Aptidão Física/fisiologia , Levantamento de Peso/fisiologia , Absorciometria de Fóton , Adulto , Pressão Sanguínea/fisiologia , Composição Corporal/fisiologia , Índice de Massa Corporal , Eletrocardiografia , Feminino , Humanos , Lipídeos/sangue , Lipoproteínas/sangue , Músculo Esquelético/fisiologia , Fonocardiografia
19.
Scand J Med Sci Sports ; 15(3): 177-81, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15885039

RESUMO

Despite the increased popularity of heart rate (HR) monitors, endurance-trained adults as well as habitual exercisers often use pulse rate palpation to periodically monitor exercise intensity. However, due to the rapid recovery of HR following exercise bouts, post-exercise palpation of pulse rates may underestimate exercise HR. To test this hypothesis, we studied 20 young physically active adults performing two sets of exercise for 5 min at 70% and 85% of maximal HR on the treadmill; one with carotid and another with radial pulse count. Post-exercise palpation of pulse rate was lower (P < 0.01) than the actual HR during exercise, underestimating exercise HR by 20-27 bpm (beats per min). Even when ECG tracings of HR were analyzed immediately after exercise (0-15 s), a significant underestimation of exercise HR (7-9 bpm) still persisted (P < 0.05). Following exercise, pulse rate obtained by carotid palpation at both intensities and radial palpation at the lower intensity was no different from the corresponding HR measured with ECG. In the radial artery trial at the higher exercise intensity, pulse rate following exercise was lower (10 bpm; P < 0.05) than ECG-derived HR. Arterial stiffness, which is closely associated with arterial baroreflex sensitivity, was not significantly related to the changes in HR with carotid palpation. We concluded that post-exercise pulse palpations may not be appropriate as an indicator of exercise intensity in habitual exercisers.


Assuntos
Exercício Físico/fisiologia , Frequência Cardíaca/fisiologia , Adolescente , Adulto , Pressão Sanguínea , Teste de Esforço , Feminino , Humanos , Masculino , Texas
20.
J Appl Physiol (1985) ; 98(6): 2287-91, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15718412

RESUMO

Decreased central arterial compliance is an emerging risk factor for cardiovascular disease. Resistance training is associated with reductions in the elastic properties of central arteries. Currently, it is not known whether this reduction is from one bout of resistance exercise or from an adaptation to multiple bouts of resistance training. Sixteen healthy sedentary or recreationally active adults (11 men and 5 women, age 27 +/- 1 yr) were studied under parallel experimental conditions on 2 separate days. The order of experiments was randomized between resistance exercise (9 resistance exercises at 75% of 1 repetition maximum) and sham control (seated rest in the exercise room). Baseline hemodynamic values were not different between the two experimental conditions. Carotid arterial compliance (via simultaneous B-mode ultrasound and applanation tonometry) decreased and beta-stiffness index increased (P < 0.01) immediately and 30 min after resistance exercise. Immediately after resistance exercise, carotid systolic blood pressure increased (P < 0.01), although no changes were observed in brachial systolic blood pressure at any time points. These measures returned to baseline values within 60 min after the completion of resistance exercise. No significant changes in these variables were observed during the sham control condition. These results indicate that one bout of resistance exercise acutely decreases central arterial compliance, but this effect is sustained for <60 min after the completion of resistance exercise.


Assuntos
Artérias Carótidas/fisiologia , Exercício Físico/fisiologia , Esforço Físico/fisiologia , Resistência Vascular/fisiologia , Adaptação Fisiológica/fisiologia , Adulto , Elasticidade , Feminino , Humanos , Masculino , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...