Heart Rate Variability Responses Research Articles

Impact of victory and defeat on the perceived stress and autonomic regulation of professional eSports athletes.

Competitive sports involve physiological, technical and psychological skills, which influence directly on individuals’ performance. This study aims to investigate the levels of perceived stress and Heart Rate Variability (HRV) before and after matches with victory and defeat in professional eSports athletes. Our hypothesis was that the winners would have better autonomic and stress responses after match, thus corroborating the literature on neurocardiac connections. Fifty male eSport players were selected players from 10 different Brazilian teams. The experiment was carried out in 2 sessions. Firstly, after signing the informed consent form, 24 h before the game, anthropometric, physical activity levels and time of expertise data were recorded only for sample characterization and the players were familiarized with the perceived stress scale—10 (PSS-10) and the HRV measurements. Secondly, players performed the PSS-10 and HRV recording at rest by 10 min 60 and 30 min before the game (i.e., baseline time) and 10 min after the end of the game. Overall, concerning PSS-10 our findings show that VG had significant reduced scores in post-game time compared to baseline (BL) and pre-game times, while DG had significant increased scores in post-game time compared to BL and pre-game times. Regarding HRV, our results demonstrate that VG had significant increase in RR, SDNN, rMSSD, pNN50 and HF, and significant decrease in LF and LF/HF, while DG had a significant decrease in RR, SDNN, rMSSD and HF, and significant increase in LF and LF/HF. It was observed that VG had better HRV responses (greater parasympathetic activation) as well as lower levels of perceived stress, while DG had worst HRV responses (greater sympathetic activation) and higher levels of perceived stress.

Association of the Heart Rate Variability Response to Active Standing with the Severity of Calcific Aortic Valve Disease: Novel Insights of a Neurocardiovascular Pathology.

The aim of this work was to obtain insights of the participation of the autonomic nervous system in different stages of calcific aortic valve disease (CAVD) by heart rate variability (HRV) analysis. Studying subjects with no valve impairments and CAVD patients, we also sought to quantify the independent contribution or explanatory capacity of the aortic valve echocardiographic parameters involved in the HRV changes caused by active standing using hierarchical partitioning models to consider other variables or potential confounders. We detected smaller adjustments of the cardiac autonomic response at active standing caused specifically by the aortic valve deterioration. The highest association (i.e., the highest percentage of independent exploratory capacity) was found between the aortic valve area and the active standing changes in the short-term HRV scaling exponent α1 (4.591%). The valve’s maximum pressure gradient echocardiographic parameter was present in most models assessed (in six out of eight models of HRV indices that included a valve parameter as an independent variable). Overall, our study provides insights with a wider perspective to explore and consider CAVD as a neurocardiovascular pathology. This pathology involves autonomic-driven compensatory mechanisms that seem generated by the aortic valve deterioration.

Obstructive sleep apnoea-related respiratory events and desaturation severity are associated with the cardiac response.

BackgroundObstructive sleep apnoea (OSA) causes, among other things, intermittent blood oxygen desaturations, increasing the sympathetic tone. Yet the effect of desaturations on heart rate variability (HRV), a simple and noninvasive method for assessing sympathovagal balance, has not been comprehensively studied. We aimed to study whether desaturation severity affects the immediate HRV.MethodsWe retrospectively analysed the electrocardiography signals in 5-min segments (n=39 132) recorded during clinical polysomnographies of 642 patients with suspected OSA. HRV parameters were calculated for each segment. The segments were pooled into severity groups based on the desaturation severity (i.e. the integrated area under the blood oxygen saturation curve) and the respiratory event rate within the segment. Covariate-adjusted regression analyses were performed to investigate possible confounding effects.ResultsWith increasing respiratory event rate, the normalised high-frequency band power (HFNU) decreased from 0.517 to 0.364 (p<0.01), the normalised low-frequency band power (LFNU) increased from 0.483 to 0.636 (p<0.01) and the mean RR interval decreased from 915 to 869 ms (p<0.01). Similarly, with increasing desaturation severity, the HFNU decreased from 0.499 to 0.364 (p<0.01), the LFNU increased from 0.501 to 0.636 (p<0.01) and the mean RR interval decreased from 952 to 854 ms (p<0.01). Desaturation severity-related findings were confirmed by considering the confounding factors in the regression analyses.ConclusionThe short-term HRV response differs based on the desaturation severity and the respiratory event rate in patients with suspected OSA. Therefore, a more detailed analysis of HRV and desaturation characteristics could enhance OSA severity estimation.

Prediction of pain responses to subsequent cold pressor test via baseline heart rate variability in healthy adults.

Baseline heart rate variability (HRV) that reflects parasympathetic nervous system (PNS) activity may serve as an objective, physiological index of pain assessment, but more research is warranted to examine the link between HRV and laboratory pain responses. This study examined whether baseline HRV would predict pain responses to subsequent cold pressor test (CPT) in healthy adults. One hundred twenty-three participants completed resting HRV assessment and CPT consisting of immersing their right hand into a cold-water bath for a maximum of 2min. Pain threshold and pain rating were assessed during CPT. Completion status of CPT, defined as completing CPT or terminating CPT before 2 min, was recorded as an additional laboratory pain measure. Pearson's correlation analysis was performed to examine the link between HRV and pain responses, whereas regression analysis was performed to test the prediction of pain responses via baseline HRV. HF-HRVlog , which reflects PNS activity, was significantly associated with the CPT completion status (r=0.23, p=0.01), but not significantly associated with pain threshold (r=0.17, p=0.06) or pain rating (r=-0.11, p=0.24). HF- HRVlog was found to be a significant predictor of CPT completion status (B=0.53, p=0.013). Baseline HF- HRVlog may serve as an objective, physiological index to predict laboratory pain responses, and the completion status of laboratory pain tests, such as CPT, may be used as a laboratory pain measure to capture important individual differences in pain processing. A better understanding of how psychophysiology relates to human pain is important. We examined the association of baseline heart rate variability (HRV) with pain response to subsequently-administered cold pressor test (CPT) in healthy adults. We found that HF-HRVlog , which reflects parasympathetic nervous system activity, predicted the completion status (completion or termination) of CPT. Baseline HF-HRVlog may serve as an objective, physiological index of pain and the completion status of CPT may help assess the important individual differences in pain processing.

Are there neurophysiological differences behind the play of different chess modalities?: An international grandmaster case study.

The study of mental load is an emerging research topic in the field of sport sciences. In the sport of chess, there is a need to understand the mental demands of the sport of chess in order to manage training loads. The present study aimed to analyze the electrical brain pattern of an elite chess player during different chess games: 15 + 10, blindfold 15 + 10, lightning game, and problem-solving chess tasks. The participant was a male 33-year-old chess player with 2562 points of ELO and more than 26 years of chess experience, training between 3 and 4 h a day. The 15 + 10 game consisted of 15 min + 10 s increment per move. In the blindfold game, the participant cannot see the positions of the pieces and does not touch them. In the lightning game, the participant played four consecutive one minute game. In addition, two high-level, two low-level, and two medium-level chess problems were performed. Electroencephalographic (EEG) and heart rate variability (HRV) responses were measured to assess the electrical brain pattern and autonomic modulation respectively. The participant won both games at 15 + 10 (normal and blindfold), lost three and drew one of the four lightning games, solved the two low-level and the two medium-level problems and solved one of the two high-level problems. Although in both games the player achieved victory the average player move quality measured with both pure analysis and analysis with additional limitations were lower in 15 + 10 blindfold game than in 15 + 10 game. Increments in theta and alpha power spectrums can be observed during the most demanding chess games (blindfold chess, lightning game, and the chess problem at difficult- level). Furthermore, the highest alpha power spectrum values can be observed during blindfold chess. In conclusion, this is the first study investigating the EEG pattern of a International Chess Grandmaster during a blindfold chess game. We found that in the chess games where lower performance is exhibited, theta and alpha power spectrums increased.

Attentional and Behavioral Disengagement as Coping Responses to Technostress and Financial Stress: An Experiment Based on Psychophysiological, Perceptual, and Behavioral Data

Discontinuance of information systems (IS) is a common phenomenon. It is thus critical to understand the decision process and psychophysiological mechanisms that underlie the intention and corresponding behaviors to discontinue IS use, particularly within the digital financial technology usage context, where continuance rates remain low despite increased adoption. Discontinuance has been identified as one coping behavior to avoid stressful situations. However, research has not yet explored this phenomenon toward digital financial technologies. This manuscript builds upon a pilot study that investigated the combined influence of technostress and financial stress on users’ responses toward digital financial decision-making tasks and aims to disentangle the specific impacts of unexpected technology behaviors and perceived financial loss on attentional and behavioral disengagement as coping responses, which may lead to discontinuance from digital financial technology usage. A two-factor within-subject design was developed, where perceived techno-unreliability as variable system response time delays under time pressure and perceived financial loss as negative financial outcomes were manipulated in a 3 × 2 design. Psychophysiological, perceptual, and behavioral data were collected from N = 15 participants while performing an adapted version of the Iowa Gambling Task. The results indicate that unexpected technology behaviors have a far greater impact than perceived financial loss on (1) physiological arousal and emotional valence, demonstrated by decreased skin conductance levels and curvilinear emotional valence responses, (2) feedback processing and decision-making, corroborated by curvilinear negative heart rate (BPM) and positive heart rate variability (HRV) responses, decreased skin conductance level (SCL), increased perceptions of system unresponsiveness and techno-unreliability, and mental workload, (3) attentional disengagement supported by curvilinear HRV and decreased SCL, and (4) behavioral disengagement as coping response, represented by curvilinear decision time and increasingly poor financial decision quality. Overall, these results suggest a feedforward and feedback loop of cognitive and affective mechanisms toward attentional and behavioral disengagement, which may lead to a decision of disengagement-discontinuance as a coping outcome in stressful human-computer interaction situations.

Heart Rate Variability for the Early Detection of Cardiac Autonomic Dysfunction in Type 1 Diabetes.

Type 1 diabetes mellitus (T1DM) has an important impact on morbidity and mortality because it may start early in life. Therefore, the early detection of cardiovascular autonomic neuropathy (DCAN) in T1DM patients is important to intervene quickly and prevent further deterioration. Traditional autonomic function tests detect abnormalities in severely symptomatic patients but they are difficult to be standardized, require the patient’s active participation and their sensitivity to the early disease is limited. In comparison, heart rate variability (HRV) is easier to be measured and standardized. Therefore, we aim to find the HRV indexes that better identify DCAN at an early stage in T1DM patients, and evaluate if HRV is a valid alternative to traditional tests. For this aim, we administered the SCOPA-AUT questionnaire on symptoms of autonomic dysfunction as well as deep breathing, Valsalva, handgrip, head-up tilt (HUT), and cold-pressor tests, to 52 T1DM patients and 27 controls. We calculated HRV indexes during supine rest (SUP) and HUT, assessing differences between groups and postures by a linear mixed-effect model for repeated measures. Receiver Operating Characteristic (ROC) analysis quantified how each HRV index and autonomic test distinguishes between patients and controls. We found that the SCOPA-AUT score was slightly but significantly (p < 0.05) greater in patients, indicating an early DCAN. T1DM patients preserved the HRV response to changing posture but in SUP they showed significantly lower standard deviation and vagal indexes of HRV than controls. The area under the ROC curve of these HRV indexes was not lower than 0.68. By contrast, traditional autonomic tests did not differ between groups. Therefore, early DCAN initially causes an impairment of the cardiac vagal control manifest in conditions of elevated vagal tone, as in SUP. Compensatory adjustments of the sympathetic control might explain the unaltered response to traditional autonomic tests. In conclusion, vagal HRV indexes in SUP help to identify early DCAN better than traditional tests, potentially allowing rapid interventions.

Acute Effects of Different Sprint Intervals on Blood Pressure, Heart Rate Variability, Lactate and Performance Responses in Physically Active Men

Background: Sprint interventions can be an excellent alternative for promoting positive adaptations to health and performance. Objectives: To verify the responses of different intervals between sprints in blood pressure, heart rate variability, lactate, and performance responses in physically active men. Methods: Ten male runners participated in the present study, trained in street running with at least one year of experience and a maximum of 3 years, with training frequency of at least two times and at the most four times weekly sessions, all participants without any kind of restrictions that could hinder the interventions—performing three sprint sessions (10 x 30m all out). Participants visited the laboratory on four occasions for ten consecutive days, with an interval of 48 hours between each visit. The first visit was intended to familiarize the participants with all experimental procedures. The remaining three visits were used to carry out the experimental protocols. At each visit, resting values ​​of blood pressure (BP), heart rate variability (HRV), and lactate variables were collected. After rest collections, each participant completed the following experimental conditions: a) 10 sprint series (all-out) of 30 meters with 20 seconds of recovery (S 20), b) 10 sprint series (all-out) of 30 meters with 30 seconds of recovery (S 30) and c) 10 sprint series (all-out) of 30 meters with 40 seconds of recovery (S 40). After each protocol, the lactate values ​​were collected 2 minutes and 30 seconds after the end of the sprints; BP was collected 60 minutes after the intervention (Post-10, Post-20, Post-30, Post-40, and Post- 50). After the blood pressure (BP) data was determined, the mean arterial pressure (MBP) was calculated using the formula MBP = SBP + (DBP X 2) / 3. The HRV was collected between 50 and 60 minutes after the end of the sprint session. Results: The study observed significant differences in the lactate variable for the comparison in the post and pre moments for all experimental conditions (S 20, S 30, and S 40) (p&lt;0.001). Besides, significant differences were observed in effort perception for S 20 and S 30 from the sixth sprint (p&lt;0.05). At S 40, significant discrepancies in effort perception started from the fifth sprint (p &lt;0.05). No other significant differences were observed for BP (systolic, diastolic and mean) for all post-pre periods. Still in BP, in a post (intra) analysis, the conditions S 20 and S 40 demonstrated greater capacity for recovery of BP, suggesting a possible greater parasympathetic capacity. For HRV and sprint performance, no difference was found (p &lt;0.05). Conclusion: The present study demonstrated that different recovery intervals did not reflect significant differences in hemodynamic, autonomic, lactate responses, and active individuals' performance submitted to sprint sessions. This study applied a protocol (10 x 30 m all out) with different recovery times (20, 30, and 40 seconds), and which, given this experiment, can serve as a training strategy (for health or performance) at different levels of physical conditioning.

Heart rate (HR) and heart rate variability (HRV) response to inhaled N, N-dimethyltryptamine (N, N-DMT): A case report

Abstract Background N, N-Dimethyltryptamine (N, N-DMT) is a naturally occurring tryptamine-based alkaloid and classic psychedelic. The potent psychoactive properties of N, N-DMT are mediated by serotonin 2A (5-HT2A) receptor agonism. There are limited investigations into the physiologic effects of inhaled N, N-DMT, despite this being one of the most common routes of administration. Heart rate variability (HRV) is an emergent non-invasive marker of cardiac autonomic nervous system (ANS) regulation and reductions in HRV have been negatively associated with multiple health outcomes. Methods A case is described with a brief review of supportive findings. Results Heart rate (HR) and HRV responses following three naturalistic inhaled N, N-DMT experiences were documented in a healthy 31-year-old male. Acute transient elevations in HR immediately following N, N-DMT administration and a pronounced elevation in the average daily HRV one-day following the experiences were observed. The duration of experience shortened across the three experiences despite similar N, N-DMT doses. Conclusion These findings offer preliminary evidence into the effect of inhaled N, N-DMT on HR and HRV. Given the emergent understanding of reductions in HRV as a hazardous marker of stress, psychiatric conditions, and mental health outcomes, further research into the effects of psychedelics on HRV is warranted.

Evaluation of an ergonomically designed schoolbag: Heart rate variability and body discomfort rating.

Unsuitable schoolbags may stress the spine and promote poor body posture, particularly for school students. Global recommendations have suggested that schoolbag weight must not exceed 10% of a healthy student's body mass, which would need continuous monitoring and enforcement. The present study presents a comparison between an ergonomically designed schoolbag, which helps reduce the potential effects of carrying a load, and a commercial one. A total of 30 healthy male students were recruited for this experiment. Independent variables determined were schoolbag type (ergonomically designed and commercial schoolbags) and three load levels based on body mass percentage (i.e., 10%, 15%, and 20% of body mass). Heart rate variability (HRV) and body discomfort rating were then measured. Our results showed that the developed schoolbag promoted enhanced subjective measures and HRV response at 15% and 20% of body mass. Participants who wore the developed schoolbags experienced significantly lesser neck, shoulder, upper and lower trunk discomfort than those who wore the traditional ones. Changing the load percentage from 10% to 15% caused an increase in heart rate among participants carrying a commercial schoolbag but a decrease in heart rate among those carrying the developed schoolbag. The findings presented herein suggest introducing strategies for reducing the potential impact of load carrying through the combined effect of new educational inventions and policy changes.

The effects of acute yoga practice on heart rate and heart rate variability responses to mental stress

ABSTRACT Yoga has been shown to reduce stress and to provide health benefits for a number of stress-related disorders. However, the effects and mechanism of an acute bout of yoga practice on relieving stress remain unclear. The aim of this study was to examine the effect of a single bout of yoga on heart rate (HR) and heart rate variability (HRV) response to and recovery from mental stress. This study was conducted with a randomised, counterbalanced, crossover design. A total of 44 participants (mean age 24.58 ± 3.84) completed two conditions (yoga and video watching (VW)) in a randomly assigned order. After each condition, participants underwent a Stroop task and mental arithmetic task. HR and HRV, measured via electrocardiogram, were recorded and analyzed at rest, during each condition, and during the stress and recovery periods. HR was significantly lower during the yoga condition as compared to that during the VW condition. There was no significant difference in HRV observed between the conditions. During both mental stress and recovery periods, there was no significant difference in HR or HRV responses between the yoga and VW conditions. These findings suggested that an acute bout of yoga practice was not superior to quiet sitting in reducing HR and HRV reactivity to and recovery from mental stress. Future studies may consider investigating individuals with exaggerated cardiovascular reactivity to further examine the potential reactivity-lowering effect of yoga.

Assessment of Heart Rate Variability Response in Children with Autism Spectrum Disorder using Machine Learning

Autism spectrum disorder (ASD) is a developmental disability that involves persistent challenges in social interaction, communication and behaviour. The purpose of this study is to apply a machine learning approach to differentiate between autistic and normal children and to evaluate the performance of different classifiers in the detection of autism disorder. Heart Rate Variability (HRV) analysis is one of the strategies used for ASD detection by assessing the autonomic nervous system (ANS), which serves as a biomarker for the autism phenotype. HRV can be derived from the photoplethysmogram (PPG). Logistic Regression, Linear Discriminant Analysis and a Cubic Support Vector Machine (SVM) were chosen to evaluate the performance of HRV features in differentiating between normal and autistic children. Three different combinations of features were selected out of 19 features in total. From the results, Logistic Regression was the best classifier to differentiate between autistic and normal children in a colour stimulus test with 100% accuracy, while Linear Discriminant Analysis was best suited in the baseline test with 90% accuracy. In conclusion, the machine learning approach could be an alternative method of making an early diagnosis of ASD in the near future.

TWO-YEAR RESPONSES OF HEART RATE AND HEART RATE VARIABILITY TO FIRST OCCUPATIONAL LEAD EXPOSURE

Objective: Because of the falling lead exposure, the literature relating autonomous nervous function to blood lead has limited relevance. Design and method: In the longitudinal Study for Promotion of Health in Recycling Lead (URL: https://www.clinicaltrials.gov; Unique identifier: NCT02243904), we recorded the 2-year responses of heart rate, heart rate variability (Cardiax, International Medical Equipment Developing, Budapest, Hungary), and median nerve conduction velocity (Brevio, NeuMed, West Trenton, NJ), a routine test in occupational medicine, to first lead exposure in 195 newly hired workers (91.3% men; mean age, 27.8 years). High- and low-frequency heart rate variability power and orthostatic heart rate variability responses were derived from 5-minute eletrocardiograms in the supine and standing positions by Fourier transform and autoregression. Blood lead was determined by inductively coupled plasma mass spectrometry. Results: From baseline to follow-up, blood lead increased from 4.22 to 14.1 ug/dL and supine/standing HR from 63.6/75.5 to 67.1/78.8 beats per minute. In analyses stratified by fourths of blood lead changes, trends in heart rate and Fourier/autoregressive heart rate variability did not reveal a dose-response curve (0.074&lt; = P&lt; = 0.98). In multivariable-adjusted mixed models, heart rate, Fourier/autoregressive heart rate variability, and nerve conduction velocity changes were unrelated to blood lead except for a weak inverse association between supine heart rate and blood lead changes (-0.55%; P = 0.029). The expected associations between heart rate variability and heart rate changes were preserved with no differences at baseline/follow-up. Analyses ichotomised by baseline median blood lead or cumulative blood lead index (4.30 ug/dL or 32.1 ug/dL × year) suggested an heart rate variability increase versus decrease in the low versus high baseline exposure group. Conclusions: Thus, a &gt; 3-fold blood lead increment did not affect autonomous neural function as captured by heart rate variability.

Effects of Acute Exercise on Cardiac Autonomic Response and Recovery in Non-Dialysis Chronic Kidney Disease Patients

ABSTRACT Purpose: Heart rate variability (HRV) has gained acceptance as a key marker of cardiovascular health. We compared HRV responses after continuous moderate-intensity exercise (CMIE) and high-intensity interval exercise (HIIE) matched for intensity and duration in individuals with midspectrum chronic kidney disease (CKD). Methods: Twenty men and women (age 62.0 ± 10 yrs.) diagnosed with CKD stages G3a and G3b participated in a 2 (condition) x 4 (time point) repeated cross-over measures design study. HRV time-domain indices were based on the standard deviation of all NN intervals (SDNN) and the square root of the mean of the sum of the squares of differences between adjacent NN intervals (RMSSD) and frequency domain. High-frequency (HF), low-frequency (LF), total power (TP) were examined. CMIE consisted of treadmill walking for 30 minutes at a 2% incline and speed corresponding to 60%–65% of reserve volume of oxygen (VO2R). HIIE included five intervals of 3 minutes at 90% of VO2R and 2 minutes at 20% VO2R intervals. Conditions were designed to be of the same average intensity (60% to 65% of VO2R) and caloric expenditure (~144 kcal). Results: Immediately following exercise SDNN, RMSSD, HF, LF, and TP were significantly lower compared to before exercise (p <.05). HRV responses were not different between conditions and conditions X time (p >.05). Conclusions: Thirty minutes of either CMIE or HIIE decreased HRV indices, pointing to an autonomic imbalance favoring vagal mediation. HRV’s responses regarding HIIE were no different from CMIE, therefore, from an autonomic function point of view this similarity may be useful for CKD exercise prescription and programming.

Impact of sodium citrate ingestion during recovery after strenuous exercise in the heat on heart rate variability: A randomized, crossover study

Changes in hydration status influence plasma volume (PV) which is associated with post‐exercise parasympathetic reactivation. The present study hypothesized that, after dehydrating cycling exercise in the heat (DE), stimulation of PV expansion with sodium citrate (CIT) supplementation would promote heart rate variability (HRV) recovery in endurance‐trained men. Twelve participants lost 4% of body mass during DE. During subsequent 16‐h recovery, participants consumed water ad libitum (CIT =5.5‐L, PLC =5.1‐L) and ate prescribed food supplemented with CIT or placebo in a randomized, double‐blind, crossover manner. Relative changes in PV were assessed across DE and 16‐h recovery. HRV was analyzed before and 16 h after DE in three conditions for altogether four 5‐min periods: supine in a thermoneutral environment, supine in the heat (32°C, 46% relative humidity; 2 periods), and standing in the heat. A larger expansion of PV across 16‐h recovery occurred in CIT compared to placebo trial (p < 0.0001). However, no between‐trial differences appeared in HRV parameters (lnRMSSD, lnSDNN, lnLF/HF) in any 5‐min period analyzed before or 16 h after DE (in all cases p > 0.05). Increases in HR (p < 0.001) and lnLF/HF (p = 0.005) and decreases in lnRMSSD (p < 0.001) and lnSDNN (p < 0.001) occurred following DE in both trials. Larger PV expansion induced by CIT supplementation after DE does not improve recovery of HRV at rest and has no influence on HRV responsiveness in endurance‐trained men.

Heart rate variability as a function of menopausal status, menstrual cycle phase, and estradiol level.

Low estradiol status is associated with increased cardiovascular risk. We sought to determine the association between heart rate variability (HRV), a marker of cardiovascular risk, at baseline and in response to stressor as a function of menopausal status, menstrual cycle phase and estradiol level. Forty‐one healthy women (13 postmenopausal, 28 premenopausal) were studied. Eleven premenopausal women were additionally studied in the high and low estradiol phases of the menstrual cycle. HRV was calculated by spectral power analysis (low Frequency (LF), high frequency (HF) and LF:HF) at baseline and in response to graded Angiotensin II (AngII) infusion. The primary outcomes were differences in HRV at baseline and in response to AngII. Compared to premenopausal women in the low estradiol phase, postmenopausal women demonstrated lower baseline LF (p = 0.01) and HF (p < 0.001) measures, which were not significant after adjustment for age and BMI. In response to AngII, a decrease in cardioprotective HRV (ΔHF = −0.43 ± 0.46 ln ms2, p = 0.005 vs. baseline) was observed in postmenopausal women versus premenopausal women. Baseline HRV parameters did not differ by menstrual phase in premenopausal women. During the low estradiol phase, no differences were observed in the HRV response to AngII challenge. In contrast, women in the high estradiol phase were unable to maintain HRV (ΔLF = −0.07 ± 0.46 ln ms2, p = 0.048 response vs. baseline, ΔHF = −0.33 ± 0.74 ln ms2, p = 0.048 response vs. baseline). No association was observed between any measure of HRV and estradiol level. Menopausal status and the high estradiol phase in premenopausal women were associated with reduced HRV, a marker of cardiovascular risk. Understanding the role of estradiol in the modulation of cardiac autonomic tone may help guide risk reduction strategies in women.

Changes in Heart Rate Variability and Post-Exercise Blood Pressure from Manipulating Rest Intervals Between Sets of Resistance Training.

The purpose of this study was to compare blood pressure and heart rate variability responses in physically active men after performing resistance training sessions with rest intervals of 1 min, 2 min and 3 min. Eighteen men (age, 21.6±1.1 years; body mass, 74.1±8.1 kg; body height, 175.3±7.1 cm) who performed 180min of physical activity per week participated in this study. After determining the 15RM loads for the squat, bench press, bent-over row and deadlift, participants performed a resistance training session. Participants performed three resistance training protocols in randomized counterbalanced order. Each experimental protocol comprised different rest intervals between sets of resistance training exercises (1min, 2min or 3min). During each experimental session, participants performed three sets with a 15RM load. Blood pressure and heart rate variability were measured before and for 2h after each session. The results demonstrated a greater blood pressure (p<0.05) reduction with a longer rest interval. There was no statistically significant difference in heart rate variability changes between groups. These results indicate that 2min and 3min rest intervals while using a 15RM load provide the best stimulus for a blood pressure reduction response after a resistance training session. Our findings suggest that strength and conditioning professionals should prescribe 2min or 3min rest intervals when resistance training is performed with a 15RM load if the aim is to obtain an acute reduction in blood pressure after a resistance training session.

Exhausted Heart Rate Responses to Repeated Psychological Stress in Women With Major Depressive Disorder.

Past research links depression and blunted cardiac vagal reactivity to chronic stress. Yet, to our knowledge no experiment investigates heart rate (variability) responses to a repeated laboratory stressor in patients with depression. Repeated exposure may provide valuable information on stress reactivity in depression. Fifty-nine women (30 inpatients diagnosed with depression and 29 matched controls) underwent two consecutive runs of a mental arithmetic stress paradigm consisting of one baseline and two exposures to control, stress, and recovery phases of 5 min each, in a case-control design. Subjective stress and electrocardiography were recorded. Variance of heart rate (HR) and root mean square of successive RR interval differences (RMSSD) were analyzed using linear mixed models. Overall, physiological parameters (HR and RMSSD) and subjective stress showed a strong group effect (all p < 0.001). In both groups, subjective stress and HR increased in response to stress, but the subjective stress levels of patients with depression did not return to baseline levels after the first stressor and for the remainder of the experiment (all p < 0.004 compared to baseline). Patients’ HR reactivity responded oppositely: while HR recovered after the first stress exposure, no reactivity was observed in response to the second exposure. These findings may suggest that the often-reported blunted HR/HRV response to stressors results from exhaustion rather than an incapacity to react to stress. The altered HR reactivity could indicate allostatic (over-) load in depression.

ANALYSIS OF HRV FOR POSTURAL CHANGE OF YOUNG ADULTS USING SIGNAL PROCESSING METHODS

Heart rate variability (HRV) is a fundamental physiological marker for assessing the autonomic nervous system’s (ANS) reaction. The response of the ANS is influenced by a variety of physical activities, i.e. body postural change. This paper aims to analyze the effect of physical activities such as postural change on HRV. To study this, a dataset of 56 subjects electrocardiogram (ECG) was self-recorded in two body postures (i) Supine and (ii) Standing. For the acquisition of ECG, the BIOPAC®MP36 system has been used at a 500Hz sampling frequency. Further, HRV signals of each subject from recorded ECG have been extracted and selected linear, and nonlinear techniques have been used to determine the effect of postural shift on it. Further, the spearman rank correlation coefficient has been evaluated between the calculated parameters to determine the correlation between linear and nonlinear parameters. The obtained results indicate that the HRV is at a higher scale in the supine posture, while it is at a lower scale when the posture has been changed from supine to standing. The change that occurred in the response of HRV with the postural change indicates that the sympathetic activation of ANS is increased in the standing body posture.

The Association between Inflammatory Biomarkers and Cardiovascular Autonomic Dysfunction after Bacterial Infection

Heart rate variability (HRV) is a known measure of cardiac autonomic function. A cardiovascular autonomic dysfunction (CAD), measured as changes in HRV, is usually presented after an infectious process. The aim of the present study is to assess the association between serum inflammatory markers and CAD. For this purpose, 50 volunteers (13 of them recovering from an infection) were recruited and followed-up for 6 weeks. Their serum inflammatory biomarkers (CRP, IL1, IL4, IL6, IL10, and TNFalpha) were quantified throughout those weeks, along with their HRV resting, in response to the Valsalva maneuver, metronome breathing, standing and sustained handgrip. The correlation of within-subject changes in both HRV and inflammatory biomarkers was assessed to evaluate the concurrent changes. An inverse within-subject correlation was found between CRP and HRV in response to the Valsalva maneuver (rho (95% CI): −0.517 (−0.877 to −0.001); p = 0.032) and HRV standing (rho (95% CI): −0.490 (−0.943 to −0.036); p = 0.034). At the beginning, increased values of CRP are found along with reduced levels of HRV. Then, the CRP was reduced, accompanied by an improvement (increase) in HRV. These results suggest that CRP is a potential marker of CAD. Whether it is the cause, the consequence or a risk indicator non-causally associated is still to be determined.