Figure - available from: European Journal of Applied Physiology
This content is subject to copyright. Terms and conditions apply.
Correlation between baseline central venous pressure and changes in mean arterial pressure in males (a) during LBNP (black circle) and HDT (white circle) and in females (b) during LBNP (black square) and HDT (white square)
Source publication
Purpose:
To determine the sex difference in the impact of central venous pressure (CVP) on the pressor response induced by ischemic handgrip exercise.
Methods:
Twelve young healthy individuals (six males, 25 ± 3 years) performed ischemic handgrip exercise during mild levels of lower body negative pressure (LBNP, -5 mmHg) and during a 10° head-do...
Similar publications
A wireless, wearable Doppler ultrasound offers a new paradigm for linking physiology to resuscitation medicine. To this end, the image analysis of simultaneously-acquired venous and arterial Doppler spectrograms attained by wearable ultrasound represents a new source of hemodynamic data. Previous investigators have reported a direct relationship be...
Citations
... The probability of occurrence of all kinds of arrhythmias was higher on the treadmill, which appeared to be further evident in males. The possible explanations for this difference in arrhythmias could be that women exhibit a lower intensity of the pressoreceptor response to exercise, which leads to a lesser increase in the sympathetic nervous system activity compared with men (23,24). Changes in the ejection fraction from rest to maximal and submaximal exercise (25), the increase in the cardiac output, and SBP * HR (26) are also reported to be relatively lower in women. ...
Background
Cardiopulmonary exercise testing (CPET) is used widely in the diagnosis, exercise therapy, and prognosis evaluation of patients with coronary heart disease (CHD). The current guideline for CPET does not provide any specific recommendations for cardiovascular (CV) safety on exercise stimulation mode, including bicycle ergometer, treadmill, and total body workout equipment.Objective
The aim of this study was to explore the effects of different exercise stimulation modes on the occurrence of safety events during CPET in patients with CHD.MethodsA total of 10,538 CPETs, including 5,674 performed using treadmill exercise and 4,864 performed using bicycle ergometer exercise at Peking University Third Hospital, were analyzed retrospectively. The incidences of CV events and serious adverse events during CPET were compared between the two exercise groups.ResultsCardiovascular events in enrolled patients occurred during 355 CPETs (3.4%), including 2 cases of adverse events (0.019%), both in the treadmill group. The incidences of overall events [235 (4.1%) vs. 120 (2.5%), P < 0.001], premature ventricular contractions (PVCs) [121 (2.1%) vs. 63 (1.3%), P = 0.001], angina pectoris [45 (0.8%) vs. 5 (0.1%), P < 0.001], and ventricular tachycardia (VT) [32 (0.6%) vs. 14 (0.3%), P = 0.032] were significantly higher in the treadmill group compared with the bicycle ergometer group. No significant difference was observed in the incidence of bradyarrhythmia and atrial arrhythmia between the two groups. Logistic regression analysis showed that the occurrence of overall CV events (P < 0.001), PVCs (P = 0.007), angina pectoris (P < 0.001), and VT (P = 0.008) was independently associated with the stimulation method of treadmill exercise. In male subjects, the occurrence of overall CV events, PVCs, angina pectoris, and VT were independently associated with treadmill exercise, while only the overall CV events and angina pectoris were independently associated with treadmill exercise in female subjects.Conclusion
In comparison with treadmill exercise, bicycle ergometer exercise appears to be a safer exercise stimulation mode for CPET in patients with CHD.
... During dynamic exercise encompassing large muscle mass (e.g., cycling), skeletal muscle pump increases venous return which might increase cardiac filling pressure, stimulating the cardiopulmonary baroreceptors and thereby dropping MSNA (8,45,46). Nonetheless, the static handgrip exercise model used in this study involves small muscle mass and it is not believed to substantially increase venous return and stimulate the cardiopulmonary baroreceptors (47). In addition, since the supine position can also stimulate the cardiopulmonary baroreceptors and influence the cardiovascular larger increase in heart rate and MSNA. ...
Exercise is a well-known sympathoexcitatory stimulus. However, muscle sympathetic nerve activity (MSNA) can decrease during the onset of muscle contraction. Yet, the underlying mechanisms and neurotransmitters involved in the sympathetic responses at the onset of exercise remain unknown. Herein, we tested the hypothesis that GABA A receptors may contribute to the MSNA responses at the onset of static handgrip in humans. Thirteen young, healthy individuals (4 females) performed 30 s of ischemic static handgrip at 30% of maximum volitional contraction before and following oral administration of either placebo or diazepam (10 mg), a benzodiazepine that enhances GABA A activity. MSNA (microneurography), beat-to-beat blood pressure (finger photopletysmography), heart rate (electrocardiogram) and stroke volume (ModelFlow) were continuously measured. Cardiac output (CO = stroke volume x heart rate) and total vascular conductance (TVC = CO / mean blood pressure) were subsequently calculated. At rest, MSNA was reduced while hemodynamic variables were unchanged after diazepam administration. Before diazepam, static handgrip elicited a significant decrease in MSNA burst frequency (∆-7±2 bursts/min, P<0.01 vs. baseline) and MSNA burst incidence (∆-16±2 bursts/100 heart beats, P<0.01 vs. baseline); however, these responses were attenuated following diazepam administration (∆-1±2 bursts/min and ∆-7±2 bursts/100 heart beats, respectively; P<0.01 vs. before diazepam). Diazepam did not affect the increases in heart rate, blood pressure, CO and TVC at the exercise onset. Importantly, the placebo had no effect on any variable at rest or exercise onset. These findings suggest that GABA A receptor activation modulates the MSNA responses at the onset of static exercise in young, healthy humans.
... The influence of gender on exercise pressor reflex was addressed in a number of studies [75][76][77][78][79]. From these investigations it can be gleaned that the metabolic part of the exercise pressor reflex (i.e. the metaboreflex) is attenuated in women as compared to men, thus resulting in reduced increase in blood pressure, sympathetic nerve activity, and central venous pressure [75,76]. ...
... The influence of gender on exercise pressor reflex was addressed in a number of studies [75][76][77][78][79]. From these investigations it can be gleaned that the metabolic part of the exercise pressor reflex (i.e. the metaboreflex) is attenuated in women as compared to men, thus resulting in reduced increase in blood pressure, sympathetic nerve activity, and central venous pressure [75,76]. This effect appears independent of muscle mass, workload, and level of training [75]. ...
Exercise is a major challenge for cardiovascular apparatus since it recruits chronotropic, inotropic, pre-load, and afterload reserves. Regular physical training induces several physiological adaptations leading to an increase in both cardiac volume and mass. It appears that several gender-related physiological and morphological differences exist in the cardiovascular adjustments and adaptations to dynamic exercise in humans. In this respect, gender may be important in determining these adjustments and adaptations to dynamic exercise due to genetic, endocrine, and body composition differences between sexes. Females seem to have a reduced vasoconstriction and a lower vascular resistance in comparison to males, especially after exercise. Significant differences exist also in the cardiovascular adaptations to physical training, with trained women showing smaller cardiac volume and wall thickness compared with male athletes. In this review, we summarize these differences.
... Surprisingly, no study has examined the impact of sampling duration on the validity (accuracy to the "true value") or reliability (consistency over time) of MSNA. This is critical, as a growing number of studies have assessed MSNA over 30 s, 1 min, or 2 min sampling durations (9,17,25,26,34,36), primarily during a baseline period before exercise. As these measures are frequently used to calculate the absolute or percent change from baseline to quantify sympathetic responsiveness (9,17,25,26,34,36), poor validity or reliability would increase the measurement error and the risk of spurious conclusions. ...
... This is critical, as a growing number of studies have assessed MSNA over 30 s, 1 min, or 2 min sampling durations (9,17,25,26,34,36), primarily during a baseline period before exercise. As these measures are frequently used to calculate the absolute or percent change from baseline to quantify sympathetic responsiveness (9,17,25,26,34,36), poor validity or reliability would increase the measurement error and the risk of spurious conclusions. Sampling durations, lasting 10 -30 s, have also been used during exercise (5,14,16,26), although the accuracy of these measurements at rest has never been established. ...
... Participants were young [23 Ϯ 6 yr (range: 18 -51)], predominantly men (n ϭ 37), with a normal body mass index [23 Ϯ 3 kg/m 2 (range: [17][18][19][20][21][22][23][24][25][26][27][28][29]], heart rate [63 Ϯ 9 beats/min (range: 48 -84)], and blood pressure [106 Ϯ 9 mmHg (range: 85-123)/64 Ϯ 6 mmHg (range: 50 -77)]. High-quality microneurographic recordings were obtained in all participants. ...
Resting muscle sympathetic nerve activity (MSNA) demonstrates high intra-individual reproducibility when sampled over 5-30 minute epochs, though shorter sampling durations are commonly used prior to, and during, a stress to quantify sympathetic responsiveness. The purpose of the present study was to examine the intra-test validity and reliability of MSNA sampled over 2-minute, 1-minute, 30-second, and 15-second epoch durations. We retrospectively analyzed 68 resting fibular nerve microneurographic recordings obtained from 53 young healthy participants (37 males; 23±6 years of age). From a stable 7 minute resting baseline, MSNA (burst frequency and incidence, normalized mean burst amplitude, total burst area) was compared between each epoch duration and a standard 5-minute control. Bland-Altman plots were used to determine agreement and bias. Three sequential MSNA measurements were collected using each sampling duration to calculate absolute and relative reliability (coefficients of variation and intra-class correlation coefficients). MSNA values were similar between each sampling duration and the 5-minute control (All p>0.05), highly correlated (r = 0.69-0.93, All p<0.001), and demonstrated no evidence of fixed bias (All p>0.05). A consistent proportional bias (p<0.05) was present for MSNA burst frequency (all sampling durations) and incidence (1-minute, 30-second, and 15-second) such that participants with low and high average MSNA underestimated and overestimated the true value, respectively. Reliability decreased progressively using the 30-second and 15-second sampling durations. In conclusion, short 2-minute, 1-minute, and 30-second sampling durations can provide valid and reliable measures of MSNA, though increased sample size may be required for epochs ≤30 seconds due to poor reliability.
New findings:
What is the central question of this study? Sympathetic vasomotor outflow is reduced during low-intensity dynamic leg exercise in younger individuals. Does aging influence the sympathoinhibitory effect during low-intensity leg cycling? What is the main finding and its importance? Muscle sympathetic nerve activity (MSNA) during low-intensity cycling decreased in older males, as seen in young males. It is possible that cardiopulmonary baroreflex-mediated inhibition of sympathetic vasomotor outflow during dynamic leg exercise is preserved in healthy older males.
Abstract:
Muscle sympathetic nerve activity (MSNA) is reduced during low-intensity dynamic leg exercise in young males. It is suggested that this inhibition is mediated by loading of the cardiopulmonary baroreceptors. The purpose of this study was to clarify the impact of age on MSNA during dynamic leg exercise. Nine younger males (YM, mean ± SD, 20 ± 1 years) and nine older males (OM, 72 ± 3 years) completed the study. The subjects performed two 4-min cycling exercises at 10% of their heart rate reserve using a cycle ergometer in a semirecumbent position [MSNA and estimated central venous pressure (eCVP) trials]. MSNA was recorded via microneurography of the left radial nerve. The CVP was estimated based on peripheral venous pressure, which was monitored using a cannula in the right large antecubital vein. The magnitude of the increase in mean arterial blood pressure during leg cycling was larger in OM (+9.3 ± 5.5 mmHg) compared with YM (+2.8 ± 4.7 mmHg). MSNA burst frequency (BF) was decreased during cycling in both YM (-8.1 ± 3.8 bursts/min) and OM (-10.6 ± 3.3 bursts/min), but no significant difference was found between the two groups. The eCVP increased during exercise in both groups, and there was no difference in the changes in eCVP between YM (+1.1 ± 0.4 mmHg) and OM (+1.2 ± 0.7 mmHg). These data indicate that inhibition of sympathetic vasomotor outflow during low-intensity cycling appears in OM as seen in YM. It is possible that the muscle pump-induced loading of the cardiopulmonary baroreflex is preserved during cycling in healthy older males. This article is protected by copyright. All rights reserved.
Blood donation entails acute reductions of cardiorespiratory fitness in healthy men. Whether these effects can be extrapolated to blood donor populations comprising women remains uncertain. The purpose of this study was to comprehensively assess the acute impact of blood withdrawal on cardiac function, central hemodynamics and aerobic capacity in women throughout the mature adult lifespan. Transthoracic echocardiography and O 2 uptake were assessed at rest and throughout incremental exercise (cycle ergometry) in healthy women (n = 30, age: 47–77 yr). Left ventricular end-diastolic volume (LVEDV), stroke volume (SV), cardiac output (Q̇) and peak O 2 uptake (V̇O 2peak ), and blood volume (BV) were determined with established methods. Measurements were repeated following a 10% reduction of BV within a week period. Individuals were non-smokers, non-obese and moderately fit (V̇O 2peak = 31.4 ± 7.3 mL·min –1 ·kg –1 ). Hematocrit and BV ranged from 38.0 to 44.8% and from 3.8 to 6.6 L, respectively. The standard 10% reduction in BV resulted in 0.5 ± 0.1 L withdrawal of blood, which did not alter hematocrit (P = 0.953). Blood withdrawal substantially reduced cardiac LVEDV and SV at rest as well as during incremental exercise (≥10% decrements, P ≤ 0.009). Peak Q̇ was proportionally decreased after blood withdrawal (P < 0.001). Blood withdrawal induced a 10% decrement in V̇O 2peak (P < 0.001). In conclusion, blood withdrawal impairs cardiac filling, Q̇ and aerobic capacity in proportion to the magnitude of hypovolemia in healthy mature women.
Novelty: The filling of the heart and therefore cardiac output are impaired by blood withdrawal in women. Oxygen delivery and aerobic capacity are reduced in proportion to blood withdrawal.
Abstract
Purpose: Males have larger blood pressure (BP) responses to relative intensity static handgrip exercise compared to females. Controlling for absolute load (maximal voluntary contraction [MVC]) abolishes these differences. Whether similar observations exist during large muscle mass exercise or dynamic contractions, and the mechanisms involved, remain unknown.
Methods: BP, heart rate, muscle oxygenation (near-infrared spectroscopy), and rectus femoris electromyography (EMG) were recorded in 28 males and 17 females during 10% and 30% MVC static (120s) and isokinetic dynamic (180s; 1:2 work-to-rest ratio; angular velocity: 60°/s) knee extensor exercise. Static and dynamic exercises were completed on separate visits, in a randomized order. Sex differences were examined with and without statistical adjustment of MVC (ANCOVA).
Results: Males had larger systolic BP responses (interaction, P<0.0001) and muscle deoxygenation (interaction, P<0.01) than females during 10% static exercise, with no difference in EMG (interaction, P=0.67). Peak systolic BP was correlated to MVC (r=0.55, P=0. 0001), and adjustment for MVC abolished sex differences in systolic BP (interaction, P=0.3). BP, heart rate, muscle oxygenation/deoxygenation, and EMG responses were similar between sexes during 30% static exercise (interaction, All P>0.2), including following adjustment for MVC (All P>0.1). Males had larger systolic BP responses during dynamic exercise at 10% and 30% (interaction, Both P=0.01), which were abolished after adjustment for MVC (interaction, Both P>0.08). Systolic BP responses were correlated with absolute MVC and stroke volume responses during 10% (r=0.31, P=0.04; r=0.61, P<0.0001, respectively) and 30% (r=0.4, P=0.007; r=0.59, P<0.0001, respectively).
Conclusions: Absolute contraction intensity can influence systolic BP responses to 10% but not 30% MVC static, as well as 10% and 30% MVC dynamic knee extensor exercise, and should be considered in cross-sectional comparisons of BP.
