Sympathetic outflow increases during head-up tilt (HUT) to stabilize blood pressure in the presence of decreases venous return and stroke volume (SV). Otherwise, orthostatic hypotension would develop. Gender differences tolerance have been noted but mechanisms are still uncertain. More recently, Waters et al. reported a limited sample, greater susceptibility women demonstrate intolerance following space flight. Therefore, it is important understand gender reflex regulation. Recently, we...

The purpose of the present study was to determine cortical structures involved with integrated baroreceptor-mediated modulation autonomic cardiovascular function in conscious humans independent changes arterial blood pressure. We assessed brain regions associated lower body negative pressure (LBNP)-induced baroreflex control using functional magnetic resonance imaging oxygen level-dependent (BOLD) contrast eight healthy male volunteer subjects. levels LBNP administered were 5, 15 and 35...

As with blood pressure, age-related changes in muscle sympathetic nerve activity (MSNA) may differ nonlinearly between sexes. Data acquired from 398 male (age: 39±17; range: 18-78 years [mean±SD]) and 260 female 37±18; 18-81 years) normotensive healthy nonmedicated volunteers were analyzed using linear regression models resting MSNA burst frequency as the outcome predictors sex, age, MSNA, body mass index modelled natural cubic splines. Age contributed 41% 11%, respectively, of variance...

Rationale: Obstructive sleep apnea and central increase risk of mortality in patients with heart failure (HF), possibly because hemodynamic compromise during sleep. However, beat-to-beat stroke volume (SV) has not been assessed response to obstructive events HF. Because generate negative intrathoracic pressure that reduces left ventricular (LV) preload increases afterload, but do not, should lead greater than events.Objectives: To determine the effects apneas hypopneas on SV HF.Methods:...

Obstructive apnea during sleep elevates the set point for efferent sympathetic outflow wakefulness. Such resetting is attributed to hypoxia-induced upregulation of peripheral chemoreceptor and brain stem function. Whether recurrent arousal from also influences daytime muscle nerve activity unknown. We therefore tested, in a cohort 48 primarily nonsleepy, middle-aged, male (30) female (18) volunteers (age: 59±1 years, mean±SE), hypothesis that frequency arousals (arousal index) would relate...

Adults are recommended to engage in 150 min of moderate (MPA) vigorous (VPA) aerobic physical activity per week, with the public health message obtaining 3000 steps 30 min. There is a paucity research on step rate thresholds that correspond absolute MVPA (moderate = 3 METs, 6 METs) no evaluating adult relative 40% VO2max, 60% VO2max). Anthropometric differences also influence intensity-related thresholds. The purpose this study was identify rates across range walking intensities so...

Introduction: Regular aerobic exercise is associated with better executive function in older adults. It unclear if high-intensity-interval-training (HIIT) elicits moderate-intensity continuous training (MICT) or resistance (RT). We hypothesized that HIIT would augment more than MICT and RT. Methods: Sixty-nine adults (age: 68 ± 7 years) performed six weeks (three days/week) of (2 × 20 min bouts alternating between 15 s intervals at 100% peak power output (PPO) passive recovery (0% PPO); n =...

An acute bout of prolonged sitting (PS) impairs the popliteal artery flow-mediated dilation (FMD) response. Despite equivocal reductions in mean shear rate, young women demonstrate an attenuated decline FMD versus men. However, it is uncertain whether endothelial-dependent vasoconstrictor responses [low-flow-mediated constriction (L-FMC)] are similarly affected by PS and/or sex differences exist. We tested hypothesis that would have both and L-FMC following PS. Popliteal were assessed via...

ABSTRACT Purpose It is unclear if high-intensity interval training (HIIT) elicits superior improvements in brachial artery (BA) flow-mediated dilation (FMD) responses (i.e., endothelial-dependent vasodilation) than moderate-intensity continuous (MICT) or resistance (RT) otherwise healthy older adults. Whether HIIT enhances lower-limb FMD and/or augments low constriction (L-FMC) (endothelial-dependent vasoconstriction) more MICT RT also unknown. We tested the hypothesis that would improve BA...

Prolonged sitting reduces lower-limb resistance vessel function (RVF), whereas increasing aerobic fitness levels enhance RVF. However, it is unknown if having higher offers protection against prolonged sitting-induced declines in This study investigated the relationships between versus reductions RVF following a 3-hour bout of uninterrupted sitting. In 30 healthy young to middle aged adults (19♀, 24±6 years), was assessed during graded, maximal cycling test. Relative peak oxygen consumption...

ABSTRACT Objective Prolonged sitting dominates workplace sedentary time (ST), This study evaluates the effects of a four-week standing desk intervention on ST, fatigue, and productivity in office workers students. Methods A with 18 (40 ± 13 years, 15 females, body mass index = 22.9 kg/m 2 ) students (21 10 26.1 ). ST was measured using Physical Activity Sedentary Behaviour Questionnaire, perceptions were assessed via surveys. Results Office reduced from 5.5 1.1 to 4.4 1.7 hours/day (p 0.01),...

Humans exposed to real or simulated microgravity experience decrements in blood pressure regulation during orthostatic stress that may be related autonomic dysregulation and/or hypovolemia. We examined the hypothesis hypovolemia, without deconditioning effects of bed rest spaceflight, would augment sympathoneural and vasomotor response graded stress. Radial artery (tonometry), stroke volume (SV), brachial flow (Doppler ultrasound), heart rate (electrocardiogram), peroneal muscle sympathetic...

The purpose of this study was to determine the effect baroreceptor unloading on sensitivity cardiovagal and sympathetic arms baroreflex during upright posture. Beat‐by‐beat R‐R interval, arterial blood pressure cardiac output (Doppler ultrasound), as well muscle nerve activity (MSNA) were recorded periods in supine (Supine) 60 deg head‐up tilt (HUT) positions (n = 8 volunteers). Cardiovagal (BRS) measured by spontaneous sequence analysis method using systolic while BRS determined slope...

In general, cardiac regulation is dominated by the sympathetic and parasympathetic nervous systems in men women, respectively. Our recent study had revealed sex differences forebrain network associated with sympathoexcitatory response to baroreceptor unloading. The present further examined modulation of cardiovagal at onset isometric exercise. Forebrain activity healthy ( n = 8) women 9) was measured using functional magnetic resonance imaging during 5 35% maximal voluntary contraction...

The study aimed to examine the effects that L-glutamine supplementation has on quadriceps muscle strength and soreness ratings following eccentric exercise. It was hypothesized glutamine ingestion would quicken recovery rate of peak force production decrease over a 72-hr period. Sixteen healthy participants (8♀/8♂; 22 ± 4 years) volunteered in double-blind, randomized, placebo-controlled crossover study. Supplement conditions consisted isoenergetic placebo (maltodextrin, 0.6 g·kg-1·day-1)...

The sympathetic excitation elicited acutely by obstructive apnea during sleep (OSA) carries over into wakefulness. We hypothesized that OSA induces structural changes in the insula and cingulate, key central autonomic network elements with projections to brainstem premotor regions. aims of this study were (1) apply two distinct but complementary methods (cortical thickness analysis [CTA] voxel-based morphometry [VBM]) compare cingulate gray matter participants without OSA; (2) determine...

The insula (IC) and cingulate are key components of the central autonomic network nodes salience (SN), a set spatially distinct but temporally correlated brain regions identified with resting-state (task free) functional MRI (rsMRI). To examine SN's involvement in sympathetic outflow, we tested hypothesis that individual differences intrinsic connectivity SN correlate positively resting postganglionic muscle nerve activity (MSNA) burst incidence (BI) subjects without obstructive sleep apnea...