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2.
J Spinal Cord Med ; : 1-8, 2020 Jan 23.
Artículo en Inglés | MEDLINE | ID: mdl-31971487

RESUMEN

Objective: The purpose of this pilot study was to determine the preliminary efficacy of interval functional electrical stimulation (FES) cycling combined with nutritional counseling in obese adults with SCI.Setting: Community-based individuals with chronic SCI.Participants: Ten participants with chronic SCI.Interventions: Participants were divided into 2 groups (1) FES cycling and nutritional counseling (FES & Nutri) and (2) nutritional counseling only (Nutri Only). The FES & Nutri group performed high intensity interval FES cycling for 30 min 3 times per week for 8 weeks and received nutritional counseling for 30 min once per week for 8 weeks. The Nutri Only group received the nutritional counseling only.Outcome Measures: Body composition (fat mass, lean mass, body fat percentage), blood glucose levels.Results: Participants in the FES & Nutri group had a statistically significant greater decrease in body fat percentage (M = -1.14) compared to those in the Nutri Only group (M = +0.28) and gained more lean mass in their legs (M = +0.66 kg) compared to the Nutri Only group (M = -1.05 kg).Discussion/Conclusion: The statistically significant decrease in body fat percentage for the FES & Nutri group provides evidence that further study is merited. Future studies should include larger numbers of participants and the possible introduction of a preliminary strengthening program before initiating interval FES cycling. In addition, an increase in exercise volume and a greater role for nutritional counseling should be considered in order to optimize the treatment for obesity.

3.
Fam Community Health ; 43(1): 1-9, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31764301

RESUMEN

Study objectives were to examine the relationships between physical activity, pain, and psychological distress in youth 8 to 17 years of age with sickle cell disease. Participants were 206 youth with sickle cell disease (M = 11.73 years, 54.9% female, 99.5% African American). Caregivers and youth completed a clinical psychosocial screening battery. Results revealed frequent pain (37.6%), moderate median pain intensity, and elevated median pain interference in youth. Lower caregiver-reported physical activity was associated with worse pain outcomes. Increased anxiety was also associated with worse pain outcomes. A better understanding of the relationship between physical activity/inactivity and pain will guide multifactorial treatment interventions.

4.
Eur J Appl Physiol ; 119(10): 2255-2263, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31420736

RESUMEN

AIM: Exercise training with blood flow restriction (BFR) increases muscle size and strength. However, there is limited investigation into the effects of BFR on cardiovascular health, particularly central hemodynamic load. PURPOSE: To determine the effects of BFR exercise on central hemodynamic load (heart rate-HR, central pressures, arterial wave reflection, and aortic stiffness). METHODS: Fifteen males (age = 25 ± 2 years; BMI = 27 ± 2 kg/m2, handgrip max voluntary contraction-MVC = 50 ± 2 kg) underwent 5-min bouts (counter-balanced, 10 min rest between) of rhythmic unilateral handgrip (1 s squeeze, 2 s relax) performed with a moderate-load (60% MVC) with and without BFR (i.e., 71 ± 5% arterial inflow flow reduction, assessed via Doppler ultrasound), and also with a low-load (40% MVC) with BFR. Outcomes included HR, central mean arterial pressure (cMAP), arterial wave reflection (augmentation index, AIx; wave reflection magnitude, RM%), aortic arterial stiffness (pulse wave velocity, aPWV), and peripheral (vastus lateralis) microcirculatory response (tissue saturation index, TSI%). RESULTS: HR increased above baseline and time control for all handgrip bouts, but was similar between the moderate load with and without BFR conditions (moderate-load with BFR = + 9 ± 2; moderate-load without BFR = + 8 ± 2 bpm, p < 0.001). A similar finding was noted for central pressure (e.g., moderate load with BFR, cMAP = + 14 ± 1 mmHg, p < 0.001). No change occurred for RM% or AIx (p > 0.05) for any testing stage. TSI% increased during the moderate-load conditions (p = 0.01), and aPWV increased above baseline following moderate-load handgrip with BFR only (p = 0.012). CONCLUSIONS: Combined with BFR, moderate load handgrip training with BFR does not significantly augment central hemodynamic load during handgrip exercise in young healthy men.


Asunto(s)
Fuerza de la Mano , Frecuencia Cardíaca , Precondicionamiento Isquémico/métodos , Acondicionamiento Físico Humano/métodos , Rigidez Vascular , Adulto , Humanos , Masculino , Músculo Esquelético/irrigación sanguínea , Músculo Esquelético/fisiología , Consumo de Oxígeno , Distribución Aleatoria
5.
Psychophysiology ; 56(12): e13457, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31420883

RESUMEN

Exposure to acute prolonged sitting reportedly leads to decreased cerebral blood flow. However, it is unclear whether this exposure translates to decreased cerebral perfusion and executive function or whether simple strategies to break up sitting can maintain cerebral perfusion and executive function. This study sought to answer two questions: in young, healthy adults, (a) does prolonged (3 hr) sitting lead to decreased cerebral perfusion and executive function? and (b) does breaking up prolonged sitting, using intermittent calf raise exercises, prevent changes in cerebral perfusion and executive function? Twenty young, healthy participants (21.7 [2.5] years, 70% female, 25.5 [6.1] kg/m2 ) were randomized to 3 hr sitting with 10 calf raises every 10 min (CALF) and 3 hr sitting without intermittent calf raises (CON). Prefrontal cortex perfusion was assessed using near-infrared spectroscopy to monitor total hemoglobin (tHB) concentration and tissue saturation index (TSI, oxygenated hemoglobin). Executive function was assessed using the Stroop word and color tasks. Following 3 hr sitting, tHb was significantly lower in CALF versus CON (-2.1 µM, 95% CI [-3.1, -1.1]). TSI was not significantly different between conditions (p = .667). Word (1.6 ms, 95% CI [0.7, 2.5]) and color (1.3 ms, 95% CI [-0.2, 2.8]) completion times were longer (worse) for CALF compared to CON. In conclusion, calf raises decreased both cerebral perfusion and executive function. Simple strategies, such as fidgeting or calf raises, which have been reported to preserve vascular function in the legs, appear not to be sufficient to benefit cerebral perfusion or executive function.

6.
J Appl Physiol (1985) ; 127(3): 781-787, 2019 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-31318613

RESUMEN

Prolonged sitting has been shown to promote endothelial dysfunction in the lower legs. Furthermore, it has been reported that simple sitting-interruption strategies, including calf raises, prevent leg endothelial dysfunction. However, it is unclear whether prolonged sitting affects central cardiovascular health, or whether simple sitting-interruption strategies prevent impaired central cardiovascular health. This study sought to answer two questions: in young, healthy adults 1) does prolonged sitting (3 h) lead to increased aortic stiffness, and 2) do intermittent calf raise exercises to prevent pooling prevent aortic stiffening. Twenty young, healthy participants (21.7 ± 2.5 yr, 70% female, 25.5 ± 6.1 kg/m2) were randomized to 3 h of sitting with (CALF) or without (CON) 10 calf raises every 10 min. Aortic stiffening [carotid-femoral pulse wave velocity (PWV)] was measured in the supine position pre- and post-sitting. Venous pooling during sitting was estimated with total hemoglobin (tHB) concentration using near-infrared spectroscopy. There were no condition × time interactions. Following 3 h of sitting, PWV significantly increased (0.30 ± 0.46 m/s, P < 0.001). There was no condition effect for PWV (P = 0.694), indicating the intermittent calf rises did not preserve central cardiovascular health. tHb was not significantly affected by sitting (P = 0.446) but was 1.9 µM higher for CON versus CALF (P = 0.106). Sitting increases aortic stiffness in young, healthy individuals, a process that may be influenced by lower extremity blood pooling. Calf raises, which have been reported to preserve vascular function in the legs, do not appear to provide sufficient stimulus for maintaining central cardiovascular health.NEW & NOTEWORTHY Although simple strategies, such as fidgeting or calf raises, are sufficient for preserving vascular function in the legs, data from the current study indicate that such strategies are not sufficient for maintaining central cardiovascular health, which is linked to cardiovascular disease.

7.
Am J Cardiol ; 123(2): 260-266, 2019 01 15.
Artículo en Inglés | MEDLINE | ID: mdl-30409414

RESUMEN

Prolonged, uninterrupted sitting negatively impacts markers of peripheral vascular health, particularly, vasodilatory function of leg arteries. Whether sitting can similarly impact measures of central vascular health, as well as overall leg vasoreactivity (i.e., vasodilatory and vasoconstrictor function) remains unknown. To address this, measurements were made in relatively healthy participants (i.e., free of overt disease; n = 20, age = 26 ± 7; body mass index = 30 ± 7 kg/m2; 7 female) pre, during and post 3 hours of uninterrupted sitting. Measures of central vascular health included arterial wave reflection (augmentation index and Reflection Magnitude-RM%) and aortic vascular stiffness (aortic pulse wave velocity). Local vasoreactivity of the distal, posterior tibial artery was measured using flow-mediated dilation-FMD, coupled with low-flow mediated constriction, and microvascular function was assessed through the total hyperemic blood velocity (area-under-curve) response during FMD. After sitting, there was a significant increase in aortic pulse wave velocity (pre sit = 5.7 ± 0.3 vs post sit = 6.1 ± 0.3 m/s; p = 0.009, d = 0.36), whereas, augmentation index decreased (pre sit = 13 ± 3 vs post sit = 3 ± 1%; p < 0.001, d = 0.71). Albeit a moderate effect for decrease, RM% was not significantly altered during sitting (p = 0.13, d = 0.3). Vasodilatory (i.e., FMD pre sit = 0.5 ± 0.04 vs post sit = 0.3 ± 0.04 mm; p = 0.014, d = 0.29) and microvascular function (i.e., Microvascular area-under-curve: pre sit = 2,196 ± 333 vs 1,157±172 AU; p = 0.003, d = 0.31) decreased, but vasoconstrictor function (low-flow mediated constriction; p = 0.85, d = 0.005) was unaffected by sitting. In conclusion, these data demonstrate that a prolonged bout of uninterrupted sitting negatively impacts markers of peripheral and central vascular health in relatively healthy adults.


Asunto(s)
Sedestación , Adulto , Aorta/fisiología , Velocidad del Flujo Sanguíneo/fisiología , Electrocardiografía , Femenino , Voluntarios Sanos , Frecuencia Cardíaca/fisiología , Humanos , Extremidad Inferior/anatomía & histología , Masculino , Microcirculación/fisiología , Análisis de la Onda del Pulso , Arterias Tibiales/diagnóstico por imagen , Arterias Tibiales/fisiología , Ultrasonografía Doppler Dúplex , Rigidez Vascular/fisiología , Vasodilatación/fisiología
8.
J Spinal Cord Med ; 42(5): 586-594, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-28770654

RESUMEN

Objective: The purpose of this pilot study was to determine whether 60 mins of intermittent pneumatic compression therapy (IPC) could acutely increase leg blood flow-induced shear stress and enhance vascular endothelial function in persons with spinal cord injury (SCI). Design: Pretest with multiple posttests, within subject randomized control design. Setting: University of Southern Mississippi, Spinal Cord Injury Research Program within the School of Kinesiology, recruiting from the local community in Hattiesburg, Jackson, and Gulfport, MS. Participants: Eight adults with SCI (injury level: T3 and below; ASIA class A-C; age: 41±17 yrs). Interventions: A 60-min IPC session was performed in one leg (experimental leg; EXP), with the other leg serving as a control (CON). Outcomes Measures: Posterior-tibial artery shear rate (Doppler-ultrasound) was examined at rest, and at 15 and 45 mins during IPC. Endothelial function was assessed using the flow-mediated dilation (FMD) technique, before and after IPC. Results: Resting FMD (mm) was similar between legs at rest. A two-way repeated measures ANOVA (leg x time) revealed that during IPC, peak shear rate increased in the EXP leg (215±137 to 285±164 s-1 at 15 mins; +39±29%, P = 0.03), with no change occurring in the CON. In addition, FMD significantly increased in the EXP leg (Pre IPC: 0.36±0.14 vs. Post IPC: 0.47±0.17 mm; P = 0.011, d = 0.66), with no change occurring in the CON leg. Conclusion: These preliminary findings suggests that IPC therapy may acutely increase leg shear stress within 15 mins, with a resultant moderate-large improvement in vascular endothelial function after 60 mins in people with SCI.

9.
Exp Physiol ; 103(4): 483-494, 2018 04 01.
Artículo en Inglés | MEDLINE | ID: mdl-29315921

RESUMEN

NEW FINDINGS: What is the central question of this study? To understand better the effects of acute hyperglycaemia on arterial stiffness in healthy young individuals, we assessed arterial stiffness in physically active men before and after reduced ambulatory physical activity to decrease insulin sensitivity. What is the main finding and its importance? During an oral glucose tolerance test, we identified an increase in leg arterial stiffness (i.e. reduced femoral artery compliance) only when subjects were inactive for 5 days (<5000 steps day-1 ) and not when they were engaging in regular physical activity (>10,000 steps day-1 ). These results demonstrate the deleterious consequence of acute reductions in daily physical activity on the response of the peripheral vasculature to acute hyperglycaemia. ABSTRACT: Acute hyperglycaemia has been shown to augment indices of arterial stiffness in patients with insulin resistance and other co-morbidities; however, conflicting results exist in healthy young individuals. We examined whether acute hyperglycaemia after an oral glucose tolerance test (OGTT) increases arterial stiffness in healthy active men before and after reduced ambulatory physical activity to decrease insulin sensitivity. High-resolution arterial diameter traces acquired from Doppler ultrasound allowed an arterial blood pressure (BP) waveform to be obtained from the diameter trace within a cardiac cycle. In 24 subjects, this method demonstrated sufficient agreement with the traditional approach for assessing arterial compliance using applanation tonometry. In 10 men, continuous recordings of femoral and brachial artery diameter and beat-to-beat BP (Finometer) were acquired at rest, 60 and 120 min of an OGTT before and after 5 days of reduced activity (from >10,000 to <5000 steps day-1 ). Compliance and ß-stiffness were quantified. Before the reduction in activity, the OGTT had no effect on arterial compliance or ß-stiffness. However, after the reduction in activity, femoral compliance was decreased (rest, 0.10 ± 0.03 mm2  mmHg-1 versus 120 min OGTT, 0.06 ± 0.02 mm2  mmHg-1 ; P < 0.001) and femoral ß-stiffness increased (rest, 8.7 ± 2.7 a.u. versus 120 min OGTT, 15.3 ± 6.5 a.u.; P < 0.001) during OGTT, whereas no changes occurred in brachial artery compliance (P = 0.182) or stiffness (P = 0.892). Insulin sensitivity (Matsuda index) was decreased after the reduction in activity (P = 0.002). In summary, in young healthy men the femoral artery becomes susceptible to acute hyperglycaemia after 5 days of reduced activity and the resultant decrease in insulin sensitivity, highlighting the strong influence of daily physical activity levels on vascular physiology.


Asunto(s)
Arteria Braquial/fisiopatología , Arterias Carótidas/fisiología , Ejercicio Físico/fisiología , Arteria Femoral/fisiología , Glucosa/metabolismo , Rigidez Vascular/fisiología , Glucemia/metabolismo , Presión Sanguínea/fisiología , Arteria Braquial/metabolismo , Arterias Carótidas/metabolismo , Femenino , Arteria Femoral/metabolismo , Prueba de Tolerancia a la Glucosa/métodos , Humanos , Hiperglucemia/metabolismo , Hiperglucemia/fisiopatología , Insulina/metabolismo , Resistencia a la Insulina/fisiología , Masculino , Persona de Mediana Edad , Actividad Motora/fisiología
10.
Hypertension ; 71(1): 192-198, 2018 01.
Artículo en Inglés | MEDLINE | ID: mdl-29203629

RESUMEN

Blacks have the highest prevalence of hypertension, putting them at greater risk of cardiovascular disease and death. Previous studies have reported that, relative to whites, healthy black men have augmented pressor responses to sympathoexcitatory stressors. Although important, these studies do not inform about the resting state and the influence of spontaneous changes in resting muscle sympathetic nerve activity (MSNA). Likewise, little is known about the transduction of MSNA into a vascular response at rest on a beat-to-beat basis. Accordingly, we tested the hypothesis that relative to whites, blacks would exhibit greater vasoconstriction and pressor responses following spontaneous bursts of MSNA. Mean arterial pressure, common femoral artery blood flow, and MSNA were continuously recorded during 20 minutes of supine rest in 35 young healthy men (17 blacks and 18 whites). Signal averaging was used to characterize changes in leg vascular conductance, total vascular conductance, and mean arterial pressure following spontaneous MSNA bursts. Blacks demonstrated significantly greater decreases in leg vascular conductance (blacks: -15.0±1.0%; whites: -11.5±1.2%; P=0.042) and total vascular conductance (blacks: -8.6±0.9%; whites: -5.1±0.4%; P=0.001) following MSNA bursts, which resulted in greater mean arterial pressure increases (blacks: +5.2±0.6 mm Hg; whites: +3.9±0.3 mm Hg; P=0.04). These exaggerated responses in blacks compared with whites were present whether MSNA bursts occurred in isolation (singles) or in combination (multiples) and were graded with increases in burst height. Collectively, these findings suggest that healthy young black men exhibit augmented sympathetic vascular transduction at rest and provide novel insight into potential mechanism(s) by which this population may develop hypertension later in life.


Asunto(s)
Presión Sanguínea/fisiología , Arteria Femoral/fisiología , Hemodinámica/fisiología , Músculo Liso Vascular , Sistema Nervioso Simpático/fisiología , Vasoconstricción/fisiología , Adulto , Afroamericanos/estadística & datos numéricos , Grupo de Ascendencia Continental Europea/estadística & datos numéricos , Frecuencia Cardíaca/fisiología , Humanos , Masculino , Músculo Liso Vascular/inervación , Músculo Liso Vascular/fisiología , Descanso/fisiología , Estados Unidos , Resistencia Vascular/fisiología
11.
Med Sci Sports Exerc ; 50(5): 1005-1014, 2018 05.
Artículo en Inglés | MEDLINE | ID: mdl-29232316

RESUMEN

INTRODUCTION: The ability to maintain functional independence in a rapidly aging population results in an increased life expectancy without corresponding increases in health care costs. The accelerated decline in V˙O2peak after the age of 65 yr is primarily due to peripheral tissue changes rather than centrally mediated factors. The purpose of this study was to determine whether the Peripheral Remodeling through Intermittent Muscular Exercise (PRIME) approach, consisting of a low-mass, high-repetition/duration skeletal muscle focused training regimen would provide superior functional benefits in participants older than 70 yr old and at risk for losing functional independence. METHODS: In this clinical trial, 107 participants were randomized to 4 wk of either standard aerobic training (AT) or PRIME (phase 1). This was followed by 8 wk of a progressive whole-body aerobic and resistance training (AT + RT) for all participants (phase 2). The major outcome measures were cardiorespiratory fitness (peak oxygen consumption [V˙O2peak]), muscular fitness (1 repetition maximal strength [1RM]), and physical function (Senior Fitness Test [SFT] scores). Results were analyzed under a per-protocol criterion. RESULTS: Thirty-eight PRIME and 38 AT participants completed the 3-month protocols. V˙O2peak, 1RM, and SFT scores all increased significantly after 12 wk for both treatment groups (P < 0.05). However, relative to AT, participants randomized to PRIME demonstrated a greater increase in V˙O2peak (2.37 + 1.83 vs 1.50 + 1.82 mL·kg·min, P < 0.05), 1RM (48.52 + 27.03 vs 28.01 + 26.15 kg, P < 0.01) and SFT (22.50 + 9.98 vs 18.66 + 9.60 percentile, P < 0.05). CONCLUSIONS: Participants experienced greater increases in cardiorespiratory and muscular fitness and physical function when PRIME training was initiated before a combined AT + RT program. This novel exercise approach may be advantageous to individuals with other chronic disease conditions characterized by low functional capacity.


Asunto(s)
Capacidad Cardiovascular , Ejercicio Físico , Músculo Esquelético/fisiología , Consumo de Oxígeno , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Entrenamiento de Resistencia
12.
J Spinal Cord Med ; 41(2): 248-252, 2018 03.
Artículo en Inglés | MEDLINE | ID: mdl-28868988

RESUMEN

BACKGROUND AND PURPOSE: Individuals with spinal cord injury (SCI) are more than twice as likely to develop and die from cardio-metabolic diseases as compared to able-bodied. This increased risk is thought to be in part due to accelerated muscle atrophy and reduced blood flow through sublesional arteries. Thus, strategies to recondition paralyzed skeletal muscles may help reduce cardio-metabolic disease risk. The purpose of this case report was to examine the impact of a novel, resistance-guided, high intensity interval training functional electrical stimulation (RG-HIIT-FES) cycling program on cardio-metabolic health in people with chronic SCI. CASE DESCRIPTION: One adult female with chronic T10 SCI. INTERVENTION: A novel RG-HIIT-FES cycling program three times per week for 10 weeks. Measures of body composition and cardio-metabolic health (vascular endothelial function of the brachial artery via flow-mediated dilation) and HbA1c blood values were performed at baseline and following completion of the RG-HIIT-FES program. OUTCOMES: Total body lean mass and legs lean mass increased 2.8% and 5.3% respectively while vastus lateralis thickness increased by 59.5%. Reactive hyperemia and flow mediated dilation change in brachial artery diameter increased by 11.1% and 147.7% following the program, respectively. HbA1c level changed minimally (5 to 4.9%). DISCUSSION: This case report suggests that RG-HIIT-FES cycling was an effective strategy to improve lean mass, and systemic vascular endothelial health in an individual with chronic SCI.


Asunto(s)
Composición Corporal/fisiología , Terapia por Estimulación Eléctrica/métodos , Entrenamiento de Intervalos de Alta Intensidad/métodos , Paraplejía/rehabilitación , Adulto , Femenino , Humanos , Extremidad Inferior/fisiopatología , Músculo Esquelético/fisiopatología , Traumatismos de la Médula Espinal/rehabilitación
13.
Exp Physiol ; 103(1): 90-100, 2018 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-29034529

RESUMEN

NEW FINDINGS: What is the central question of this study? Continuous-wave near-infrared spectroscopy, coupled with venous and arterial occlusions, offers an economical, non-invasive alternative to measuring skeletal muscle blood flow and oxygen consumption, but its reliability during exercise has not been established. What is the main finding and its importance? Continuous-wave near-infrared spectroscopy devices can reliably assess local skeletal muscle blood flow and oxygen consumption from the vastus lateralis in healthy, physically active adults. The patterns of response exhibited during exercise of varying intensity agree with other published results using similar methodologies, meriting potential applications in clinical diagnosis and therapeutic assessment. Near-infrared spectroscopy (NIRS), coupled with rapid venous and arterial occlusions, can be used for the non-invasive estimation of resting local skeletal muscle blood flow (mBF) and oxygen consumption (mV̇O2), respectively. However, the day-to-day reliability of mBF and mV̇O2 responses to stressors such as incremental dynamic exercise has not been established. The aim of this study was to determine the reliability of NIRS-derived mBF and mV̇O2 responses from incremental dynamic exercise. Measurements of mBF and mV̇O2 were collected in the vastus lateralis of 12 healthy, physically active adults [seven men and five women; 25 (SD 6) years old] during three non-consecutive visits within 10 days. After 10 min rest, participants performed 3 min of rhythmic isotonic knee extension (one extension every 4 s) at 5, 10, 15, 20, 25 and 30% of maximal voluntary contraction (MVC), before four venous occlusions and then two arterial occlusions. The mBF and mV̇O2 increased proportionally with intensity [from 0.55 to 7.68 ml min-1  (100 ml)-1 and from 0.05 to 1.86 ml O2  min-1  (100 g)-1 , respectively] up to 25% MVC, where they began to plateau at 30% MVC. Moreover, an mBF/mV̇O2 muscle oxygen consumption ratio of ∼5 was consistent for all exercise stages. The intraclass correlation coefficient for mBF indicated high to very high reliability for 10-30% MVC (0.82-0.9). There was very high reliability for mV̇O2 across all exercise stages (intraclass correlation coefficient 0.91-0.96). In conclusion, NIRS can reliably assess muscle blood flow and oxygen consumption responses to low- to moderate-intensity exercise, meriting potential applications in clinical diagnosis and therapeutic assessment.


Asunto(s)
Ejercicio Físico/fisiología , Músculo Esquelético/irrigación sanguínea , Músculo Esquelético/fisiología , Consumo de Oxígeno/fisiología , Flujo Sanguíneo Regional/fisiología , Espectroscopía Infrarroja Corta/normas , Adolescente , Adulto , Femenino , Humanos , Masculino , Reproducibilidad de los Resultados , Espectroscopía Infrarroja Corta/métodos , Adulto Joven
14.
Eur J Appl Physiol ; 117(10): 2075-2083, 2017 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-28821962

RESUMEN

Previous work has demonstrated a direct relationship between aerobic fitness and vasodilatory function (i.e., flow-mediated dilation; FMD); however, the relation between aerobic fitness and vasoconstrictor responsiveness (i.e., low flow-mediated constriction; L-FMC), and the overall vasoactive range (FMD + L-FMC) is unclear. PURPOSE: To test the hypothesis that L-FMC and the overall vasoactive range (FMD + L-FMC) will be related to aerobic fitness in young, healthy men. METHODS: Twenty men (age: 23 ± 5 years) were recruited, and divided evenly into a higher (HF) vs. lower (LF) aerobic fitness group, quantified via YMCA cycle ergometry (VO2 peak extrapolation), and a 3-min step test (1-min heart rate recovery). Duplex Doppler-ultrasound was used to assess brachial artery FMD and L-FMC. RESULTS: Estimated VO2 peak (HF = 55 ± 10 vs. LF = 38 ± 5 mL/kg/min) and heart rate recovery (HF = 36 ± 10 vs. LF = 25 ± 8 beats) were greater in the HF group (P < 0.05). FMD and the vasoactive range were similar between groups; however, L-FMC was significantly greater in HF (HF = -2.5 ± 1.6 vs. LF = -0.7 ± 1.8%, P < 0.05; d = 1.18). A correlational analysis revealed an inverse relationship between L-FMC and both HR recovery (r = -0.665, P < 0.01) and estimated VO2 peak (r = -0.5, P < 0.05). CONCLUSIONS: This work supports an association between L-FMC and aerobic fitness in young, healthy men. Longitudinal or interventional studies are warranted to support causality, and to distinguish whether L-FMC is more sensitive to changes in aerobic fitness than FMD.


Asunto(s)
Ejercicio Físico/fisiología , Vasoconstricción , Adulto , Arteria Braquial/diagnóstico por imagen , Arteria Braquial/fisiología , Capacidad Cardiovascular , Humanos , Masculino , Consumo de Oxígeno
15.
J Appl Physiol (1985) ; 122(1): 38-47, 2017 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-27789766

RESUMEN

Increased endothelin-1 (ET-1) and reduced endothelial nitric oxide phosphorylation (peNOS) are hypothesized to reduce insulin-stimulated blood flow in type 2 diabetes (T2D), but studies examining these links in humans are limited. We sought to assess basal and insulin-stimulated endothelial signaling proteins (ET-1 and peNOS) in skeletal muscle from T2D patients. Ten obese T2D [glucose disposal rate (GDR): 6.6 ± 1.6 mg·kg lean body mass (LBM)-1·min-1] and 11 lean insulin-sensitive subjects (Lean GDR: 12.9 ± 1.2 mg·kg LBM-1·min-1) underwent a hyperinsulinemic-euglycemic clamp with vastus lateralis biopsies taken before and 60 min into the clamp. Basal biopsies were also taken in 11 medication-naïve, obese, non-T2D subjects. ET-1, peNOS (Ser1177), and eNOS protein and mRNA were measured from skeletal muscle samples containing native microvessels. Femoral artery blood flow was assessed by duplex Doppler ultrasound. Insulin-stimulated blood flow was reduced in obese T2D (Lean: +50.7 ± 6.5% baseline, T2D: +20.8 ± 5.2% baseline, P < 0.05). peNOS/eNOS content was higher in Lean under basal conditions and, although not increased by insulin, remained higher in Lean during the insulin clamp than in obese T2D (P < 0.05). ET-1 mRNA and peptide were 2.25 ± 0.50- and 1.52 ± 0.11-fold higher in obese T2D compared with Lean at baseline, and ET-1 peptide remained 2.02 ± 1.9-fold elevated in obese T2D after insulin infusion (P < 0.05) but did not increase with insulin in either group (P > 0.05). Obese non-T2D subjects tended to also display elevated basal ET-1 (P = 0.06). In summary, higher basal skeletal muscle expression of ET-1 and reduced peNOS/eNOS may contribute to a reduced insulin-stimulated leg blood flow response in obese T2D patients. NEW & NOTEWORTHY: Although impairments in endothelial signaling are hypothesized to reduce insulin-stimulated blood flow in type 2 diabetes (T2D), human studies examining these links are limited. We provide the first measures of nitric oxide synthase and endothelin-1 expression from skeletal muscle tissue containing native microvessels in individuals with and without T2D before and during insulin stimulation. Higher basal skeletal muscle expression of endothelin-1 and reduced endothelial nitric oxide phosphorylation (peNOS)/eNOS may contribute to reduced insulin-stimulated blood flow in obese T2D patients.


Asunto(s)
Diabetes Mellitus Tipo 2/metabolismo , Endotelina-1/metabolismo , Insulina/metabolismo , Músculo Esquelético/metabolismo , Óxido Nítrico Sintasa/metabolismo , Obesidad/metabolismo , Circulación Renal/fisiología , Adulto , Diabetes Mellitus Tipo 2/fisiopatología , Femenino , Arteria Femoral/metabolismo , Arteria Femoral/fisiopatología , Glucosa/metabolismo , Técnica de Clampeo de la Glucosa/métodos , Humanos , Resistencia a la Insulina/fisiología , Masculino , Persona de Mediana Edad , Músculo Esquelético/fisiopatología , Óxido Nítrico Sintasa de Tipo III/metabolismo , Obesidad/fisiopatología , Delgadez/metabolismo , Delgadez/fisiopatología
16.
Clin Physiol Funct Imaging ; 37(4): 421-427, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-26749070

RESUMEN

Analysis of heart rate variability (HRV) responses to an orthostatic challenge can be used to investigate autonomic control of heart rate, an index of cardiovascular function. HRV is typically assessed using the electrocardiogram (ECG), which can be impractical for use with large population-based studies. PURPOSE: To assess the validity and reliability of telemetry-derived HRV responses to an orthostatic challenge. METHODS: Twenty healthy adults (26 + 5 years, 45% male) were tested on three separate mornings. Following 20-min supine rest, R-R intervals were recorded using a telemetric device during three conditions: BASE, TILT and RECOVERY. ECG was simultaneously used on 1 day for validity comparison. Measures of HRV included the following: standard deviation of normal-to-normal intervals (SDNN), the root-mean-square of successive differences (RMSSD) and the low-frequency (LF) and high-frequency (HF) spectral power. RESULTS: For all parameters, there was excellent agreement between devices for BASE (r = 0·96-0·99), TILT (r = 0·89-1·00) and RECOVERY (r = 0·96-1·00). For the telemetric device, between-day intraclass coefficient values for RMSDD, SDNN and HF were all above the 0·75 criterion for each condition, indicating excellent between-day reliability. For each condition, the reliability coefficient, expressed as a percentage of the mean (RC%), was marginally lower (greater reliability) for RMSDD (RC% 11-13) and SDNN (RC% 10-12) compared to HF (RC% 12-17). However, SDNN did not significantly respond to the orthostatic challenge. CONCLUSION: Telemetric HRV, particularly RMSDD and HF, can be used to provide a sensitive, valid and reliable assessment of autonomic control of heart rate.


Asunto(s)
Mareo/diagnóstico , Frecuencia Cardíaca , Estrés Fisiológico , Telemetría/métodos , Adulto , Mareo/fisiopatología , Electrocardiografía , Femenino , Humanos , Masculino , Posicionamiento del Paciente , Valor Predictivo de las Pruebas , Reproducibilidad de los Resultados , Pruebas de Mesa Inclinada , Factores de Tiempo , Adulto Joven
18.
Exp Physiol ; 100(7): 829-38, 2015 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-25929229

RESUMEN

NEW FINDINGS: What is the central question of this study? The prevalence of sedentary behaviour in the workplace and increased daily sitting time have been associated with the development of cardiovascular disease; however, studies investigating the impact of sitting on vascular function remain limited. What is the main finding and its importance? We demonstrate that there is a marked vulnerability of the vasculature in the lower and upper limbs to prolonged sitting and highlight the importance of physical activity in restoring vascular function in a limb-specific manner. Sedentary behaviour in the workplace and increased daily sitting time are on the rise; however, studies investigating the impact of sitting on vascular function remain limited. Herein, we hypothesized that 6 h of uninterrupted sitting would impair limb micro- and macrovascular dilator function and that this impairment could be improved with a bout of walking. Resting blood flow, reactive hyperaemia to 5 min cuff occlusion (microvascular reactivity) and associated flow-mediated dilatation (FMD; macrovascular reactivity) were assessed in popliteal and brachial arteries of young men at baseline (Pre Sit) and after 6 h of uninterrupted sitting (Post Sit). Measures were then repeated after a 10 min walk (~1000 steps). Sitting resulted in a marked reduction of resting popliteal artery mean blood flow and mean shear rate (6 h mean shear rate, -52 ± 8 s(-1) versus Pre Sit, P < 0.05). Interestingly, reductions were also found in the brachial artery (6 h mean shear rate, -169 ± 41 s(-1) versus Pre Sit, P < 0.05). Likewise, after 6 h of sitting, cuff-induced reactive hyperaemia was reduced in both the lower leg (-43 ± 7% versus Pre Sit, P < 0.05) and forearm (-31 ± 11% versus Pre Sit, P < 0.05). In contrast, popliteal but not brachial artery FMD was blunted with sitting. Notably, lower leg reactive hyperaemia and FMD were restored after walking. Collectively, these data suggest that prolonged sitting markedly reduces lower leg micro- and macrovascular dilator function, but these impairments can be fully normalized with a short bout of walking. In contrast, upper arm microvascular reactivity is selectively impaired with prolonged sitting, and walking does not influence this effect.


Asunto(s)
Brazo/irrigación sanguínea , Arteria Braquial/fisiología , Postura/fisiología , Flujo Sanguíneo Regional/fisiología , Vasodilatación/fisiología , Adulto , Velocidad del Flujo Sanguíneo/fisiología , Humanos , Pierna/irrigación sanguínea , Masculino , Factores de Tiempo
19.
Med Sci Sports Exerc ; 47(5): 1087-94, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25207931

RESUMEN

PURPOSE: Insulin-stimulated increases in skeletal muscle blood flow play a role in glucose disposal. Indeed, 7 d of aerobic exercise in patients with Type 2 diabetes increased blood flow responses to an oral glucose tolerance test (OGTT) and improved insulin sensitivity. More recent work suggests that reduced daily physical activity impairs glycemic control (GC) in healthy individuals. Herein, we sought to determine whether an acute reduction in daily activity (from >10,000 to <5000 steps per day) for 5 d (RA5) in healthy individuals reduced insulin-stimulated blood flow and GC in parallel and if a 1-d return to activity (RTA1) improved these outcomes. METHODS: OGTT were performed as a stimulus to increase insulin in 14 healthy, recreationally active men (24 ± 1.1 yr) at baseline, RA5, and RTA1. Measures of insulin sensitivity (Matsuda index) and femoral and brachial artery blood flow were made during the OGTT. Free-living measures of GC including peak postprandial glucose (peak PPG) were also made via continuous glucose monitoring. RESULTS: Femoral and brachial artery blood flow increased during the OGTT but neither was significantly impacted by changes in physical activity (P > 0.05). However, insulin sensitivity was decreased by RA5 (11.3 ± 1.5 to 8.0 ± 1.0, P < 0.05). Likewise, free-living GC measures of peak PPG (113 ± 3 to 123 ± 5 mg·dL(-1), P < 0.05) was significantly increased at RA5. Interestingly, insulin sensitivity and GC as assessed by peak PPG were not restored after RTA1 (P > 0.05). CONCLUSIONS: Thus, acute reductions in physical activity impaired GC and insulin sensitivity; however, blood flow responses to an OGTT were not affected. Further, a 1-d return to activity was not sufficient to normalize GC after 5 d of reduced daily physical activity.


Asunto(s)
Glucemia/metabolismo , Glucosa/administración & dosificación , Insulina/sangre , Actividad Motora/fisiología , Músculo Esquelético/irrigación sanguínea , Periodo Posprandial/fisiología , Arteria Braquial/fisiología , Dieta , Arteria Femoral/fisiología , Prueba de Tolerancia a la Glucosa , Humanos , Masculino , Flujo Sanguíneo Regional , Adulto Joven
20.
J Appl Physiol (1985) ; 118(4): 455-64, 2015 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-25539935

RESUMEN

Rapid-onset vasodilation (ROV) following single muscle contractions has been examined in the forearm of humans, but has not yet been characterized in the leg. Given known vascular differences between the arm and leg, we sought to characterize ROV following single muscle contractions in the leg. Sixteen healthy men performed random ordered single contractions at 5, 10, 20, 40, and 60% of their maximum voluntary contraction (MVC) using isometric knee extension made with the leg above and below heart level, and these were compared with single isometric contractions of the forearm (handgrip). Single thigh cuff compressions (300 mmHg) were utilized to estimate the mechanical contribution to leg ROV. Continuous blood flow was determined by duplex-Doppler ultrasound and blood pressure via finger photoplethysmography (Finometer). Single isometric knee extensor contractions produced intensity-dependent increases in peak leg vascular conductance that were significantly greater than the forearm in both the above- and below-heart level positions (e.g., above heart level: leg 20% MVC, +138 ± 28% vs. arm 20% MVC, +89 ± 17%; P < 0.05). Thigh cuff compressions also produced a significant hyperemic response, but these were brief and smaller in magnitude compared with single isometric contractions in the leg. Collectively, these data demonstrate the presence of a rapid and robust vasodilation to single muscle contractions in the leg that is largely independent of mechanical factors, thus establishing the leg as a viable model to study ROV in humans.


Asunto(s)
Contracción Isométrica/fisiología , Pierna/fisiología , Músculo Esquelético/fisiología , Vasodilatación/fisiología , Adulto , Presión Sanguínea/fisiología , Antebrazo/fisiología , Humanos , Hiperemia/fisiopatología , Rodilla/fisiología , Masculino , Flujo Sanguíneo Regional/fisiología , Muslo/fisiología
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