Differences In Cardiovascular Responses Research Articles

The impact of uninterrupted sitting on central and peripheral cardiovascular function in pre-menopausal and post-menopausal women.

Independently, both prolonged uninterrupted sitting and the onset of menopause negatively impact markers of cardiovascular risk. Whether their combination augment these responses additively remains unknown. This study assessed whether prolonged uninterrupted sitting causes greater central and peripheral cardiovascular dysfunction in post-menopausal women compared to pre-menopausal women. To address this, 23 healthy women (13 pre-menopausal [43.77 ± 4.30years] and 10 post-menopausal [57.20 ± 8.55years]) sat uninterrupted for 2-h. Carotid-femoral pulse wave velocity (cf-PWV), pulse wave analysis (PWA), lower limb venous pooling (HHb), and calf circumference were assessed pre-and post-sitting using general linear mixed models, with age as a covariate. Changes in MAP over time (both between and within groups) was assessed using a two-way repeated-measures-ANOVA. There were no significant interactions for any outcome measures. However, for cf-PWV, there was a significant main effect of group (Δ = 0.854 ± 0.354m s-1; p = 0.026, ηp2 = 0.707). For PWA, only heart rate (HR) and pressure forwards (Pf) showed significant main effects 13 of time [Δ = 6 ± 1 bts-min-1, p < 0.001, ηp2 = 0.861] and group [Δ = 3.893 ± 1.450mmHg, p = 0.016, ηp2 = 0.271], respectively. Both HHb (Δ = 2.737 ± 0.952, p = 0.009, ηp2 = 0.742) and calf circumference (Δ = 0.812 ± 0.128cm, p < 0.001, ηp2 = 0.863) significantly increased over time. Whilst post-menopausal women demonstrated greater overall arterial stiffness (increased cf-PWV at baseline), there was no difference in cardiovascular response (central or peripheral) to 2-h of prolonged sitting between the pre- and post-menopausal women.

Consideration of absolute intensity when examining sex differences in blood pressure responses during static exercise.

Low- to moderate-intensity submaximal static contractions are commonly used to study the effects of biological sex on the cardiovascular response to exercise. Under this paradigm, premenopausal females frequently demonstrate smaller blood pressure responses than age-matched males. These differences are preserved during postexercise circulatory occlusion, implicating the muscle metaboreflex as an important driver of sex differences in the blood pressure response to static exercise. The mechanisms responsible for these differences are incompletely understood but often attributed to innate sex differences in skeletal muscle fiber type distribution, muscle metabolism, and/or sympathetic control of the circulation. However, one potential confounding factor is that the majority of studies use relative intensity exercise (e.g., 30% of maximal voluntary contraction), such that on average, females are completing static contractions at a lower absolute intensity. In this review, we summarize human evidence showing that sex differences in blood pressure responses to static exercise are attenuated or abolished when controlling for absolute intensity and muscle strength, either by statistical methods or strength-matched cohorts. We highlight evidence that the effect of higher absolute contraction intensity on exercise blood pressure likely occurs through increased mechanical occlusion of skeletal muscle microvasculature, leading to greater activation of the muscle metaboreflex. These findings highlight an important need to account for absolute intensity when studying and interpreting sex differences in cardiovascular responses to exercise.

Age Comparisons of Cardiac Work During Exercise in Women: Insight from Acute β1 Adrenergic Blockade

Postmenopausal women exhibit exaggerated increases in blood pressure during activities of daily living and exercise. The decreased size and increased stiffening of postmenopausal women's hearts elevate myocardial oxygen demand when compared to age-matched men and younger cohorts. Together, this poses a risk to the safety of, and capacity for, exercise in postmenopausal women. We recently studied the effects of esmolol, a fast-acting, cardio-selective β1 antagonist, on oxygen transport variables during dynamic exercise in healthy young (Y) and older (O) women to better understand differences in cardiovascular responses to exercise. Objective: Determine the effects of acute cardiac specific blockade on myocardial oxygen demand (rate pressure product, RPP) and cardiac work (CW) in healthy young premenopausal and older postmenopausal women. Methods: Thirteen healthy young (20-32 yr) and older postmenopausal (58-70 yr) women performed moderate (85% of lactate threshold) and heavy (50% between lactate threshold and the respiratory compensation point) recumbent leg cycling exercise during IV infusion of saline or esmolol in randomized order. Whole body oxygen consumption (VO2, indirect calorimetry), brachial systolic blood pressure (SBP, automated cuff), heart rate (HR, ECG), and cardiac output (CO, bioimpedance) were measured continuously. RPP (HR×SBP), CW (CO×SBP), and cardiac effciency (CE, CW/VO2) were calculated. Mixed model repeated measures ANOVAs were used to determine the effect of treatment and age group. Results: Power outputs were lower in O vs. Y at both moderate (45±9W and 72±15W, p&lt;0.001) and heavy (81±21W vs. 117±32W, p&lt;0.001) intensities. During the saline trial CO was lower (p&lt;0.001), and RPP was higher (p&lt;0.001) in the O vs. Y group during both intensities. There was a main effect of treatment on RPP, CW, and CE. Esmolol reduced RPP (4638±775 SD, p&lt;0.001), CW (547±89, p&lt;0.001) and CE (1682±62, p&lt;0.001) in both O and Y. There was a main effect of age group on CE, pairwise comparisons showed CE was lower in O than Y (441±112, p&lt;0.001). Conclusions: Older postmenopausal women experience higher myocardial oxygen demand and perform more cardiac work for a given whole body liter oxygen consumed during dynamic leg exercise compared to younger premenopausal women. Acute β1 adrenergic blockade narrows the gap between central cardiovascular function in young and old women and provides a powerful tool to investigate age-related cardiovascular differences. NIH R21 AG054940. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Cardiovascular response of students to physical exertion using the 'Trunk Flexion Test'

Background and Study Aim. Multiple factors affect the health condition of students. In this regard, a key preventative measure is observing the students' level of physical preparedness. The aim of the study is to assess the cardiovascular system response of students to physical exercise using the 'Trunk Flexion Test'. Material and Methods. This study included 77 students from the physical education faculties of three universities in Ukraine, comprising 34 males and 43 females. The cardiovascular system's response was gauged using the 'Trunk Forward Flexion Test'. Data on participants were compiled through Google Form. Statistical evaluation was conducted using PyCharm CE and Python programming libraries. ANOVA was utilized to determine the differences in cardiovascular responses among students, and Pearson's correlation coefficient explored the relationship between body mass index and cardiovascular function. Results. Research findings show gender-based disparities in cardiovascular system responses (CVSR). Women outperformed men in achieving 'Excellent' ratings. Women also led in 'Good' and 'Average' evaluations, while men were more likely to be in 'Undesirable' and 'Hazardous' categories. Differences were noted in body mass index. The proportion of students with normal weight differed by university. The prevalence of overweight varied among universities. The occurrence of 'Underweight' and 'Obese' also varied by university. An elevation in body mass index was correlated with a decline in CVSR in men. Conclusions. Variations in CVSR highlight the importance of implementing wellness initiatives and encouraging students to enhance their physical activity levels.

Cardiovascular responses to combined mechanoreflex and metaboreflex activation in healthy adults: effects of sex and low- versus high-hormone phases in females.

Females generally have smaller blood pressure (BP) responses to isolated muscle mechanoreflex and metaboreflex activation compared with males, which may explain sex differences in BP responses to voluntary exercise. The mechanoreflex may be sensitized during exercise, but whether mechanoreflex-metaboreflex interactions differ by sex or variations in sex hormones remains unknown. Thirty-one young healthy subjects (females, n = 16) performed unilateral passive cycling (mechanoreflex), active cycling (40% peak Watts), postexercise circulatory occlusion (PECO; metaboreflex), and passive cycling combined with PECO (combined mechanoreflex and metaboreflex activation). Beat-to-beat BP, heart rate, inactive leg vascular conductance, and active leg muscle oxygenation were measured. Ten females underwent exploratory testing during low- and high-hormone phases of their self-reported menstrual cycle or oral contraceptive use. Systolic BP and heart rate responses did not differ between sexes during active cycling [Δ30 ± 9 vs. 29 ± 11 mmHg (males vs. females), P = 0.9; Δ33 ± 8 vs. 35 ± 6 beats/min, P = 0.4] or passive cycling with PECO (Δ26 ± 11 vs. 21 ± 10 mmHg, P = 0.3; Δ14 ± 7 vs. 18 ± 15 beats/min, P = 0.3). Passive cycling with PECO revealed additive, not synergistic, effects for systolic BP [males: Δ23 ± 14 vs. 26 ± 11 mmHg (sum of isolated passive cycling and PECO vs. combined activation); females: Δ26 ± 11 vs. 21 ± 12 mmHg, interaction P = 0.05]. Results were consistent in subset analyses with sex differences in active cycling BP (P > 0.1) and exploratory analyses of hormone phase (P > 0.4). Despite a lack of statistical equivalence, no differences in cardiovascular responses were found during combined mechanoreflex-metaboreflex activation between sexes or hormone levels. These results provide preliminary data regarding the involvement of muscle mechanoreflex-metaboreflex interactions in mediating sex differences in voluntary exercise BP responses.NEW & NOTEWORTHY The muscle mechanoreflex may be sensitized by metabolites during exercise. We show that cardiovascular responses to combined mechanoreflex (passive cycling) and metaboreflex (postexercise circulatory occlusion) activation are primarily additive and do not differ between males and females, or across variations in sex hormones in females. Our findings provide new insight into the contributions of muscle mechanoreflex-metaboreflex interactions as a cause for prior reports that females have smaller blood pressure responses to voluntary exercise.

A cross-sectional study of influence of cerebral dominance on cardiovascular responses to autonomic stressor tests in adolescents

Background: Hand preference is perhaps the most obvious behavioral asymmetry observed in humans and is related to cerebral dominance. Animal and human studies have shown that cerebral cortex has a definite role in regulation of cardiovascular autonomic activity. Each hemisphere exhibits differential control over dynamics of heart especially the sympathetic activity is controlled by right hemisphere insula in particular. Hence, the present study was conducted to evaluate influence of cerebral dominance (handedness) on cardiovascular responses such as heart rate (HR) and blood pressure (BP) indices to autonomic stressor tests in the left and right hander adolescents. Aims and Objectives: The aim of the study was to evaluate the differences in cardiovascular responses in the left and right handers to autonomic stressor tests. Materials and Methods: The present cross-sectional study was conducted in 35 right and 35 left hander students of age group 16–20 years. Autonomic stressor tests used in the study were handgrip dynamometry and cold pressor test (CPT). Results: The right and left handers had similar baseline values of BP and HR. All the subjects responded to Autonomic function tests by increased BP and HR from baseline. The absolute BP values and change in BP from baseline were significantly higher in the left than right handers both during and after the tests. HR values showed significant differences in peak values during both the tests. Visual analog score was similar during CPT in both groups. Conclusion: The HR and BP responses to autonomic stressor tests are higher in the left handers than right handers supports the fact that the right hemisphere has more influence on sympathetic activity of heart.

Sex differences in cardiovascular response to sepsis.

Recently, there has been increased recognition of the importance of sex as a biological factor affecting disease and health. Many preclinical studies have suggested that males may experience a less favorable outcome in response to sepsis than females. The underlying mechanisms for these differences are still largely unknown but are thought to be related to the beneficial effects of estrogen. Furthermore, the immunosuppressive role of testosterone is also thought to contribute to the sex-dependent differences that are present in clinical sepsis. There are still significant knowledge gaps in this field. This mini-review will provide a brief overview of sex-dependent variables in relation to sepsis and the cardiovascular system. Preclinical animal models for sepsis research will also be discussed. The intent of this mini-review is to inspire interest for future considerations of sex-related variables in sepsis that should be addressed to increase our understanding of the underlying mechanisms in sepsis-induced cardiovascular dysfunction for the identification of therapeutic targets and improved sepsis management and treatment.

"Differential Cardiovascular Responses to Static and Dynamic Exercises"

"Differential Cardiovascular Responses to Static and Dynamic Exercises"

Comparing The Resting Cardiovascular Response To Commonly Used Blood Flow Restriction Devices

Alone, blood flow restriction is used to decrease muscle atrophy or recovery time. However, it is unknown whetherdevices used in clinical or research settings elicit a similar stimulus when using similar protocols. PURPOSE: To compare cardiovascular responses between a commonly used research device (RES) and clinical device (CLIN). METHODS: Over one visit, 24 individuals’ cardiovascular response to blood flow restriction using CLIN and RES devices were measured on the right arm in a randomized and counterbalanced order. After 5 min of supine rest, arterial occlusion pressure (AOP) was measured, then during a second 5 min rest, a near-infrared spectroscopy device was placed at the muscle belly of the forearm to measure tissue deoxygenation (HHb, μm) and tissue saturation index (TSI, %). A pulse oximeter on the index finger measured heart rate (bpm) and % oxygen saturation. 0-10 scale ratings of perceived discomfort (RPE-D, AU) were also assessed. Blood flow (ml/min) was measured using pulsed wave Doppler ultrasonography at the brachial artery proximal to the antecubital space. All variables were assessed twice at 0% AOP and once at 50% AOP. Measures were spaced 1 min apart. Change scores (50% AOP - 0% AOP) and AOP presented as mean ± SD, were compared using Bayesian paired samples t-tests (JASP). RESULTS: AOP differed between RES (157.13 ± 19.54) and CLIN (143.17 ± 16.92; BF10 = 156.75). However, weak to moderate evidence suggested that changes in blood flow volume (RES: -33.13 ± 30.64; CLIN: -28.71 ± 28.75; BF10 = .41), TSI (RES: -4.68 ± 5.17; CLIN: -4.92 ± 5.50; BF10 = 0.23), heart rate (RES: 0 ± 3; CLIN: 0 ± 7; BF10 = 0.22), and oxygen saturation (RES: -1 ± 1; CLIN: -1 ± 1; BF10 = 0.25) did not differ between the devices. Moderate evidence suggested HHb for channel 1 (RES: 16.48 ± 5.50; CLIN: 16.41 ± 6.69; BF10 = 0.22), channel 2 (RES: 16.12 ± 4.84; CLIN: 15.89 ± 6.21; BF10 = 0.22), and channel 3 did not differ (RES: 15.44 ± 4.53; CLIN: 15.13 ± 5.78; BF10 = 0.23) between devices. Moderate evidence also suggested RPE-D did not differ (RES: 1.06 ± 1.29; CLIN: 1.10 ± 1.30; BF10 = 0.22). CONCLUSION: AOP measurements differed between devices, possibly due to cuff width, material, and/or assessment method. However, this did not lead to a difference in cardiovascular responses when applying a relative pressure of 50% AOP for each device.

Editor's Roundup for Issue #3 of 2022: Advances in ECT Research Methodology, ECT in Persons With Borderline Traits, Benign Effect of ECT on Executive Function, and Differences in Cardiovascular Response Between ECT and MST.

Editor's Roundup for Issue #3 of 2022: Advances in ECT Research Methodology, ECT in Persons With Borderline Traits, Benign Effect of ECT on Executive Function, and Differences in Cardiovascular Response Between ECT and MST.

A comparative study of cardiovascular responses to exercise in trained and untrained individuals

Background: This experiment has been designed for you to learn more about the way the cardiovascular system how it respond toward exercise. The prevalence of cardiovascular disease and its resultant debilitation of cardiac performance are expected to increase in the future generation. Eelier research on cardiovascular adaptations to endurance training has primarily focused on young generation. Recent work on the present study indicates that the basis of trained older male’s increased aerobic power is their superior ability to increase stroke volume during exercise, which, in turn, allows them to marked increase in cardiac output. Aims and Objectives: The aim of the study was to assess the differences in cardiovascular responses to exercise in trained and untrained individuals. Materials and Methods: In this, 100 subjects were included and divided into trained (50) and untrained (50) for a minimum of 1 year duration by the time of study and 50 untrained individuals acted as controls. Institution ethics committee permission obtained and the subjects performed four exercise sessions per week for a minimum of 1 year duration by the time of study; supervised by the personal trainers at gym center, according to instructions. Results: The mean resting heart rate (HR) of strength trained was lesser when compared to mean resting HR of untrained. Conclusion: Regular strength training exercise results in a decrease in weight, body fat, resistance of insulin, triglycerides, and an increase in excess good cholesterol levels. Regular strength training exercise if performed within normal limits decreases cardiovascular risk factors.

130 Individual Differences in Skin Temperature Responses to Cold Pressor Stress During Sleep Restriction and Circadian Misalignment

Abstract Introduction Individual differences in cognition during sleep restriction and circadian misalignment have been shown to be trait-like. Here we explored the consistency of individual differences in cardiovascular responses to the cold pressor test (CPT) measured by changes in the distal-proximal skin temperature gradient (DPG) using the contralateral hand to that immersed in the ice water bath, which reflects a reflex cutaneous vasoconstriction. Methods Eighteen healthy participants (8 females) mean (±SD) age 25.28 (±4.3), underwent two identical in-laboratory combined sleep restriction and circadian misalignment protocols preceded by an 8h baseline in-laboratory sleep opportunity. The participants were given a 3h sleep opportunity on night 2 and a 3h sleep opportunity on days 3 and 4 followed by recovery sleep. The CPT occurred the morning after the baseline sleep opportunity and the morning before recovery sleep. Participants maintained a seated posture beginning 30 min prior to the CPT and skin temperature was assessed starting 15 min before until 45 min after the CPT. DPG (proximal=subclavicular; distal=hand palmar) data were averaged into 3 min bins. Changes in DPG from pre-CPT and 5 min post-CPT were assessed as the primary outcome using mixed-model ANOVAs. Intra-class correlation coefficients (ICC) were calculated to measure consistency of individual differences for DPG responses. Results Mixed-model ANOVA revealed significant effects of time and combined sleep restriction and circadian misalignment on DPG during the CPT (both p&amp;lt;0.05), such that the DPG was wider (i.e., more negative) post-CPT and during sleep restriction and circadian misalignment. Participants showed moderately consistent DPG responses across visits 1 and 2 at baseline (ICC=0.59) and substantially consistent DPG responses during sleep restriction and circadian misalignment (ICC=0.67). Further, participants showed moderately consistent DPG responses when comparing changes between baseline and sleep restriction and circadian misalignment across visits (ICC=0.58). Conclusion Findings support that combined sleep restriction and circadian misalignment is associated with sympathetic activation and that individual differences in the DPG response to cold pressor stress are consistent. Support (if any) Office of Naval Research MURI grant N00014-15-1-2809, NIH/NCATS Colorado CTSA Grant UL1TR002535

Modeling individual differences in cardiovascular response to gravitational stress using a sensitivity analysis

The human cardiovascular (CV) system elicits a physiological response to gravitational environments, with significant variation between different individuals. Computational modeling can predict CV response, however model complexity and variation of physiological parameters in a normal population makes it challenging to capture individual responses. We conducted a sensitivity analysis on an existing 21-compartment lumped-parameter hemodynamic model in a range of gravitational conditions to 1) investigate the influence of model parameters on a tilt test CV response and 2) to determine the subset of those parameters with the most influence on systemic physiological outcomes. A supine virtual subject was tilted to upright under the influence of a constant gravitational field ranging from 0 g to 1 g. The sensitivity analysis was conducted using a Latin hypercube sampling/partial rank correlation coefficient methodology with subsets of model parameters varied across a normal physiological range. Sensitivity was determined by variation in outcome measures including heart rate, stroke volume, central venous pressure, systemic blood pressures, and cardiac output. Results showed that model parameters related to the length, resistance, and compliance of the large veins and parameters related to right ventricular function have the most influence on model outcomes. For most outcome measures considered, parameters related to the heart are dominant. Results highlight which model parameters to accurately value in simulations of individual subjects' CV response to gravitational stress, improving the accuracy of predictions. Influential parameters remain largely similar across gravity levels, highlighting that accurate model fitting in 1 g can increase the accuracy of predictive responses in reduced gravity.NEW & NOTEWORTHY Computational modeling is used to predict cardiovascular responses to altered gravitational environments. However, considerable variation between subjects and model complexity makes accurate parameter assignment for individuals challenging. This computational effort studies sensitivity in cardiovascular model outcomes due to varying parameters across a normal physiological range. This allows determination of which parameters have the largest influence on outcomes, i.e., which parameters must be most carefully selected to give accurate predictions of individual responses.

CENTRAL INTEGRATION OF LEFT VERSUS RIGHT BARORECEPTOR AFFERENT INPUT IN FEMALE SPONTANEOUSLY HYPERTENSIVE RATS

Objective: Neuromodulation of blood pressure using baroreflex activation therapy is an effective means to control hypertension in resistant hypertensive patients. In a genetic rat model of essential hypertension, the spontaneously hypertensive rats (SHRs); we were able to demonstrate in male rats that preferential central integration of left baroreceptor afferent input exists relative to that of the right afferents. It remains unknown whether laterality also influences baroreflex responses in female SHRs. Accordingly, the differences in cardiovascular responses triggered by stimulation of the left and right baroreceptor afferents, as assessed by direct electrical stimulation of the aortic depressor nerve (ADN), were studied in female SHRs. Design and method: Pentobarbital-anesthetized female SHRs (25–29 weeks, n = 6–8) were instrumented for left and right ADN stimulation (1–40 Hz, 0.2 ms, 0.4 mA for 20 s) and recording of mean arterial pressure (MAP), heart rate (HR) and mesenteric (MVR) and femoral (FVR) vascular resistance. Female rats were also matched for the diestrus phase of the estrus cycle. Results: Both left and right ADN stimulation resulted in frequency-dependent reductions (P &lt; 0.001) in MAP, HR, MVR and FVR. Reflex reductions in MAP, HR, MVR and FVR were comparable for both left-sided and right-sided stimulation. Conclusions: Unlike males, female SHRs express no differential central modulation of baroreceptor afferent input as evidenced by the comparable left versus right baroreflex-mediated depressor responses. Similar depressor responses in the left versus right stimulation may have been contributed to by the lack of differences in baroreflex-driven changes in HR and vascular resistance. Clinically, targeting either the left or right aortic nerves may equally provide adequate reductions in blood pressure in female hypertensive subjects. Future studies should elucidate the mechanisms responsible for sex differences in the central processing of baroreflex between male and female SHRs.

Blood Pressure and Risk of Cognitive Impairment: The Role of Vascular Disease in Neurodegeneration.

(1) Background: Both cerebral vascular disorders and cognitive decline increase in incidence with age. The role of cerebral vascular disease and hemodynamic changes in the development of cognitive deficits is controversial. The objective of this study was to assess the cardiovascular response during cardiac stress testing in neurologically asymptomatic individuals who developed cognitive impairment several years after previous cardiac stress testing. (2) Methods: This was a retrospective cohort study of patients who underwent cardiac stress testing between January 2001 and December 2010. Patients were followed up until May 2015, and we selected those who developed cognitive dysfunction including dementia, mild cognitive impairment, and subjective cognitive decline, after the stress test. Heart rate and blood pressure both at rest and at peak exercise, and the mean R-R interval at rest were recorded. For each patient who developed cognitive impairment, we selected one matched control who did not show cognitive decline by the end of the follow-up period. (3) Results: From the cohort of 7224 patients, 371 developed cognitive impairment; of these, 186 (124 men) met the inclusion criteria, and 186 of the other patients were selected as matched controls. During follow-up, cognitive impairment appeared 6.2 ± 4.7 years after the cardiac stress test. These patients who had subsequently developed cognitive impairment had significantly lower at-rest systolic, diastolic, and mean blood pressure than controls (p < 0.05). Further, compared with controls, their maximum heart rate was significantly higher at peak exercise. (4) Conclusion: The results from this study suggest that differences in cardiovascular response to stress might be present in individuals who develop cognitive decline. These findings challenge the possibility of assessing blood pressure and heart rate variability at rest and during cardiac stress as potential risk factors associated with cognitive impairment.

No Effects of Different Doses of New Zealand Blackcurrant Extract on Cardiovascular Responses During Rest and Submaximal Exercise Across a Week in Trained Male Cyclists.

Supplementation with anthocyanin-rich blackcurrant increases blood flow, cardiac output, and stroke volume at rest. It is not known whether cardiovascular responses can be replicated over longer timeframes in fed trained cyclists. In a randomized, double-blind, crossover design, 13 male trained cyclists (age 39 ± 10 years, V˙O2max 55.3 ± 6.7ml·kg-1·min-1) consumed two doses of New Zealand blackcurrant (NZBC) extract (300 and 600mg/day for 1 week). Cardiovascular parameters were measured during rest and submaximal cycling (65% V˙O2max) on day 1 (D1), D4, and D7. Data were analyzed with an RM ANOVA using dose (placebo vs. 300 vs. 600mg/day) by time point (D1, D4, and D7). Outcomes from placebo were averaged to determine the coefficient of variation within our experimental model, and 95% confidence interval (CI) was examined for differences between placebo and NZBC. There were no differences in cardiovascular responses at rest between conditions and between days. During submaximal exercise, no positive changes were observed on D1 and D4 after consuming NZBC extract. On D7, intake of 600mg increased stroke volume (3.08ml, 95% CI [-2.08, 8.26]; d = 0.16, p = .21), cardiac output (0.39L/min, 95% CI [-1.39, .60]; d = 0.14, p = .40) (both +2.5%), and lowered total peripheral resistance by 6.5% (-0.46mmHg·min/ml, 95% CI [-1.80, .89]; d = 0.18, p = .46). However, these changes were trivial and fell within the coefficient of variation of our study design. Therefore, we can conclude that NZBC extract was not effective in enhancing cardiovascular function during rest and submaximal exercise in endurance-trained fed cyclists.

Cerebrovascular responses to graded exercise in young healthy males and females.

Although systemic sex‐specific differences in cardiovascular responses to exercise are well established, the comparison of sex‐specific cerebrovascular responses to exercise has gone under‐investigated especially, during high intensity exercise. Therefore, our purpose was to compare cerebrovascular responses in males and females throughout a graded exercise test (GXT). Twenty‐six participants (13 Females and 13 Males, 24 ± 4 yrs.) completed a GXT on a recumbent cycle ergometer consisting of 3‐min stages. Each sex completed 50W, 75W, 100W stages. Thereafter, power output increased 30W/stage for females and 40W/stage for males until participants were unable to maintain 60‐80 RPM. The final stage completed by the participant was considered maximum workload(W max). Respiratory gases (End‐tidal CO2, EtCO2), middle cerebral artery blood velocity (MCAv), heart rate (HR), non‐invasive mean arterial pressure (MAP), cardiac output (CO), and stroke volume (SV) were continuously recorded on a breath‐by‐breath or beat‐by‐beat basis. Cerebral perfusion pressure, CPP = MAP (0. 7,355 distance from heart‐level to doppler probe) and cerebral vascular conductance index, CVCi = MCAv/CPP 100mmHg were calculated. The change from baseline (Δ) in MCAv was similar between the sexes during the GXT (p = .091, ω p 2 = 0.05). However, ΔCPP (p < .001, ω p 2 = 0.25) was greater in males at intensities ≥ 80% W max and ΔCVCi (p = .005, ω p 2 = 0.15) was greater in females at 100% W max. Δ End‐tidal CO2 (ΔEtCO2) was not different between the sexes during exercise (p = .606, ω p 2 = −0.03). These data suggest there are sex‐specific differences in cerebrovascular control, and these differences may only be identifiable at high and severe intensity exercise.

Frequency and perceptions of life stress are associated with reduced cardiovascular stress-response adaptation

Psychological stress is a risk factor for cardiovascular disease. Individual differences in cardiovascular responses to stress may be an underlying mechanism. The literature examining the relationships between frequency and perceptions of life stress with cardiovascular reactivity to acute stress in the laboratory is inconclusive. Recent work highlights the need to measure cardiovascular reactivity across multiple stress exposures to obtain more comprehensive profiles of reactivity by assessing adaptation over time. The aims of the current study were to examine the relationships between frequency and perceptions of stressful life events with cardiovascular reactivity, as well as adaptation of cardiovascular reactivity over time. Four hundred and fifty-three healthy, young adults (mean (SD) age = 19.5 (1.3) years, 62% female, 66.2% Caucasian, 17.7% Hispanic) completed a single laboratory visit, which included two identical, stress-testing protocols, each consisting of a 10-minute baseline and 4-minute stress task. Heart rate (HR) and systolic/diastolic blood pressure (S/DBP) were recorded throughout. Participants completed the Undergraduate Stress Questionnaire (USQ) and Perceived Stress Scale (PSS). Results indicate that greater frequency and perceptions of life stress were independently associated with blunted HR and DBP reactivity at the first stress exposure and less habituation of HR and DBP reactivity across both exposures, even after controlling for confounding variables. The present study suggests that higher frequency and perceptions of stress in daily life may harm the body's ability to respond effectively to short-term stress and also disrupt healthy adaptation of stress responses over repeated exposures, thus increasing risk of cardiovascular disease outcomes.

Difference in cardiovascular response during orthostatic stress in Parkinson's disease and multiple system atrophy.

Although orthostatic hypotension is more prominent in multiple system atrophy (MSA) than in Parkinson's disease (PD), there is no study comparing the degree of decrease in total peripheral resistance and cardiac response during orthostatic stress between both diseases. In this study, we examined whether there is a difference in cardiovascular response between MSA and PD. We examined the results of the head-up tilt test in 68 patients with MSA, 28 patients with cardiac non-denervated PD, and 70 patients with cardiac denervated PD whose total peripheral resistance after 60° tilting was lower than the value at 0°. Differences in cardiac output and blood pressure changes were compared against the decrease in total peripheral resistance. There was no difference in the degree of decrease in total peripheral resistance among the three groups. However, the slope of the regression line revealed that the increase in cardiac output against the change in total peripheral resistance was significantly lower in the MSA group than in the cardiac non-denervated and denervated PD groups, and that the decrease in systolic blood pressure against the change in total peripheral resistance was significantly greater in the MSA group than in the cardiac non-denervated and denervated PD groups. In MSA, the cardiac response during orthostatic stress is lower than that in PD, possibly underlying the fact that orthostatic hypotension is more prominent in MSA than in PD.

Racial Differences In Cardiovascular Responses Following Acute Bouts Of Anaerobic Exercise

Despite the growing popularity of high-intensity anaerobic exercise, few studies have examined the acute effects of this form of exercise on cardiovascular hemodynamics, or potential racial differences in these responses. In addition, post exercise hypotension may be absent in African Americans (AA) following aerobic exercise, consistent with their higher risk for hypertension. It is unknown whether AA and Caucasian Americans (CA) would exhibit different blood pressures following acute bouts of anaerobic exercise. PURPOSE: To assess hemodynamic changes in healthy, young AA and CA women following repeated bouts (two) of maximal anaerobic exercise. METHODS: Eight young, healthy AA women and 9 CA women completed this study. Vascular and hemodynamic measurements were taken at rest, and 5 (P5-1st), 15 (P15-1st), and 30 minutes (P30-1st) following a maximal anaerobic exercise test on cycle ergometer, and 5 (P5-2nd), 15 (P15-2nd), and 30 (P30-2nd) minutes following the second maximal anaerobic exercise test. Brachial systolic (SBP), diastolic (DBP) blood pressures, central aortic SBP, DBP and mean arterial blood pressure (aortic MAP) were measured. Carotid arterial stiffness (beta-stiffness index) were obtained using ultrasonography. RESULTS: Data were presented in Table 1 as mean ± standard error. Resting DBP and aortic DBP were significantly different between AA and CA (§ p<0.05). There was a significant race by time interaction for aortic MAP (* p<0.05). And there was a trend towards significance in race by time interaction for beta stiffness index (p=0.06). CONCLUSION: Acute bouts of anaerobic exercise increase aortic MAP in young AA but not in CA, and it may be related to increases in arterial stiffness in AA. The heightened BP and vascular responses to exercise stimulus may play a role in the pathogenesis of hypertension in AA. Supported by New England ACSM New Investigator Award to HY.Table 1: Hemodynamic responses to two acute bouts of maximal anaerobic exercise.