Heart Rate Variability Indices Research Articles

Cardiac Autonomic Modulation in Domestic Cats with Obstructive Lower Urinary Tract Disease

Obstructive feline lower urinary tract disease (OFLUTD) is the most common complication of the urinary system, as metabolic and electrolyte changes can alter the functioning of the autonomic nervous system (ANS). The objective of this study was to describe the indices of heart rate variability (HRV) and their correlations with the observed alterations in Systolic Blood Pressure (SBP) and electrocardiographic, biochemical, and haemogasometric indices in cats diagnosed with OFLUTD. Sixty-five male cats up to 10 years of age were divided into two groups. The control group (CG) was composed of 25 healthy cats, and the obstructed group (OG) consisted of 40 cats with OFLUTD. The OG was evaluated by electrocardiography and blood pressure at four different time points. In the CG, electrocardiographic evaluation and SBP measurement were performed. A comparison of the HRV between the CG and OG (M0) revealed differences in the SDNN (standard deviation of all normal RR-NN) parameters (sympathetic and parasympathetic tone) and in the rMSSD (parasympathetic tone); there was a difference in the SBP, which was greater in the CG. There were higher rates in the CG. The HF and HR were greater in OG. The HRV serves as a preventive tool and predicts the severity of OFLUTD in patients due to an imbalance in the ANS.

Association of ambient ozone exposure with early cardiovascular damage among general urban adults: A repeated-measures cohort study in China

Longitudinal evidence of long-term ozone exposure on heart rate variability (HRV, an early indicator of cardiovascular damage) is lacking and the potential mechanism remains largely unclear. Our objectives were to evaluate the cross-sectional and longitudinal associations of ozone exposure with HRV alteration, and the potential roles of protein carbonyl (PC, biomarker of oxidative protein damage) and transforming growth factor (TGF)-β1 in this association. This repeated-measures prospective study included 4138 participants with 6617 observations from the Wuhan-Zhuhai cohort. Ozone concentrations were estimated using a high temporospatial resolution model for each participant. HRV indices, PC, and TGF-β1 were also repeatedly measured. Cross-sectional and longitudinal relationships of ozone exposure with HRV alteration were evaluated by linear mixed model. Cross-sectionally, the strongest lag effect of each 10 ppb increment in short-term ozone exposure showed a 12.40 %, 8.47 %, 4.31 %, 8.03 %, 3.69 %, and 2.41 % decrement on very low frequency (VLF, lag 3 weeks), LF (lag 2 weeks), high frequency (HF, lag 0–7 days), total power (TP, lag 2 weeks), standard deviation of all normal-to-normal intervals (SDNN, lag 3 weeks), and square root of the mean squared difference between adjacent normal-to-normal intervals (lag 2 weeks), respectively. Longitudinally, each 10 ppb increment of annual average ozone was related with an annual change rate of −0.024 ms2/year in VLF, −0.009 ms2/year in LF, −0.013 ms2/year in HF, −0.014 ms2/year in TP, and −0.004 ms/year in SDNN. Mediation analyses indicated that PC mediated 20.77 % and 12.18 % of ozone-associated VLF and TP decline, respectively; TGF-β1 mediated 16.87 % and 27.78 % of ozone-associated VLF and SDNN reduction, respectively. Our study demonstrated that ozone exposure was cross-sectionally and longitudinally related with HRV decline in general Chinese urban adults, and oxidative protein damage and increased TGF-β1 partly mediated ozone exposure-related HRV reduction.

Analyze the Effect of Steel Waste on Performance Characteristics of Concrete

This cross-sectional study investigates the immediate impact of occupational stress on short-term heart rate variability (HRV) and muscle strength among 200 construction workers in Chennai. The Perceived Stress Scale (PSS) was employed to assess stress levels, while HRV was measured using a portable ECG device, focusing on time-domain (RMSSD) and frequency-domain (HF Power) parameters. Muscle strength was evaluated using a MicroFET 2 dynamometer. Pearson correlation and multivariate regression analyses were applied to determine the associations between stress, HRV, and muscle strength, adjusting for confounding factors such as age, body mass index (BMI), and work duration. Results revealed a significant negative correlation between perceived stress and both HRV indices (RMSSD: r=-0.45, p<0.01; HF Power: r=-0.50, p<0.01) as well as muscle strength (r=-0.40, p<0.01). Higher stress levels were associated with reduced HRV and diminished muscle strength. Regression analyses confirmed that stress independently predicted lower HRV (RMSSD: ?=-0.35, p<0.01; HF Power: ?=-0.42, p<0.01) and decreased muscle strength (?=-0.32, p<0.01). These findings suggest that elevated stress negatively impacts both cardiovascular and muscular functioning, potentially increasing the health risks among construction workers. The study highlights the importance of implementing stress management interventions to improve both the physical well-being and productivity of workers in the construction industry.

Association of Sympathovagal Imbalance with Increased Inflammation and Impaired Adaptive Immunity in Bladder Cancer Patients

Stress responses can impact bladder cancer (BC) outcomes via immune–inflammatory pathway modulation. This study explores heart rate variability (HRV) associations with serum immune–inflammatory biomarkers, blood count inflammatory markers, and psychosocial self-report measures in patients versus healthy controls. The TREM-1 and TREM-2 expressions on peripheral blood monocytes were analysed via flow cytometry; serum inflammatory biomarkers by ELISA; HRV (5-min ECG) pre-tumour resection; blood counts by haematology analyser; and psychosocial factors by validated questionnaires. Patients exhibited altered immune–inflammatory profiles with increased TREM-1/TREM-2, sTREM-1, sTREM-1/sTREM-2 ratio, BDNF, MCP-1, and NLR, and reduced IFN-γ, IL-10, LMR, and PMR. HRV analysis indicated sympathetic dominance (SNS, Stress indices, ACmod) and reduced parasympathetic modulation (PNS index, SDNN, RMSSD, 2UV%, DCmod, SD1). Sympathetic HRV indices correlated positively with sTREM-1, sTREM-1/sTREM-2 ratio, fractalkine, and inflammatory markers (SII, NLR, PLR) and negatively with parasympathetic HRV indices—correlations absent in controls. Only in patients, reduced physical function and social support, and higher anxiety, depression, and fatigue, associated positively with sympathetic HRV indices and inflammatory markers. This study links immune–inflammatory markers, HRV parameters, and psychosocial factors in BC, suggesting that immune and autonomic variations may relate to unfavourable outcomes. Incorporating these assessments could help tailor more personalised treatment strategies for BC patients.

RHRVEasy: Heart rate variability made easy.

Heart Rate Variability (HRV) analysis aims to characterize the physiological state affecting heart rate, and identify potential markers of underlying pathologies. This typically involves calculating various HRV indices for each recording of two or more populations. Then, statistical tests are used to find differences. The normality of the indices, the number of groups being compared, and the correction of the significance level should be considered in this step. Especially for large studies, this process is tedious and error-prone. This paper presents RHRVEasy, an R open-source package that automates all the steps of HRV analysis. RHRVEasy takes as input a list of folders, each containing all the recordings of the same population. The package loads and preprocesses heart rate data, and computes up to 31 HRV time, frequency, and non-linear indices. Notably, it automates the computation of non-linear indices, which typically demands manual intervention. It then conducts hypothesis tests to find differences between the populations, adjusting significance levels if necessary. It also performs a post-hoc analysis to identify the differing groups if there are more than two populations. RHRVEasy was validated using a database of healthy subjects, and another of congestive heart failure patients. Significant differences in many HRV indices are expected between these groups. Two additional groups were constructed by random sampling of the original databases. Each of these groups should present no statistically significant differences with the group from which it was sampled, and it should present differences with the other two groups. All tests produced the expected results, demonstrating the software's capability in simplifying HRV analysis. Code is available on https://github.com/constantino-garcia/RHRVEasy.

Study of physiological reactions in healthy individuals in different microclimate: a pilot study

Introduction. Studying the influence of meteorological and heliophysical factors on the human body is an urgent problem in restorative medicine. Aim. To study the characteristics of the microclimatic zones of the territory of the village of Arkhipo-Osipovka, the Black Sea coast of the Krasnodar Territory and the physiological parameters of healthy volunteers before and after the terrainkur in order to assess the effectiveness of its individual routes. Materials and methods. Bioclimatic zoning of the territory of the SKK “Vulan” was carried out, the village of Arkhipo-Osipovka, the Black Sea coast of the Krasnodar Territory, according to standard methods in October 2023. In October 2023, a clinical study was conducted with the participation of 12 healthy volunteers, using a cross-sectional study design. All study participants went through a standard health path route every day in different microclimatic zones, before and after which a psychophysiological study was carried out, heart rate variability (HRV) was assessed, microcirculation and composition body weight using the bioimpedance method. Results and discussion. It was revealed that the psychophysiological state of the volunteers was characterized by overstrain of regulatory systems (the median indicator of activity of regulatory systems in all zones was 7.0); after the health path, statistically significant changes in HRV, hemodynamic parameters, microcirculation and body composition were noted (p 0.05). However, the rate of increase or decrease in indicators was heterogeneous in different microclimates (p 0.05). According to the results of the cluster analysis, the circulation regime was associated with indicators of HRV and microcirculation, and ambient temperature with HRV and body composition. When analyzing the body’s adaptive response to the influence of climatic factors and identified microclimatic zones, the same type of nonspecific response of the body of healthy volunteers to physical activity was recorded, but the degree of severity of this response was different. Conclusion. The introduction of bioclimatic zoning in sanatorium-resort organizations will allow optimizing health path techniques, due to the possibility of dosing the climatic load, by determining the optimal location, time of year and microclimate for conducting sanatorium-resort treatment.

Unraveling the complex interplay between curved tunnels and drivers’ physiological responses: An HRV perspective

This study aims to unravel the complex interplay between curved tunnels and drivers’ physiological responses from an HRV (Heart Rate Variability) perspective.A group of 30 individuals with valid driver’s licenses was selected, and their HRV was monitored while driving through four curved tunnels in Yunnan Province, China. HRV indicators such as RMSSD (Root Mean Square of Successive Differences), SDNN (Standard Deviation of Normal-to-Normal Intervals), LF (Low Frequency), and LF/HF (ratio of Low Frequency to High Frequency) were analyzed. The independent variables included tunnel radius, turn direction, and zone characteristics. The results demonstrated that the radius, turning, and zone of the curved tunnel significantly influenced drivers’ HRV. Specifically, as the tunnel radius decreased, the mean RMSSD and SDNN of drivers decreased, while the mean LF and LF/HF increased. In left turns, drivers had lower RMSSD and SDNN values but higher LF and LF/HF ratios compared to right turns. Additionally, drivers showed the highest mean RMSSD and SDNN in the entrance zone of the tunnel, followed by the middle zone, and the lowest in the exit zone. Conversely, the exit zone had the highest mean LF and LF/HF, followed by the middle zone, and the entrance zone had the lowest. These results indicate that the characteristics of the curved tunnel have a substantial impact on drivers’ physiological responses. A smaller tunnel radius leads to increased stress and cognitive load, as reflected by the decreased HRV metrics and increased sympathetic activity. Turning maneuvers, particularly left turns, result in asymmetry in autonomic responses, with lower RMSSD and SDNN and higher LF and LF/HF during left turns. The variations in HRV across different zones within the tunnel suggest that environmental cues play a role in sympathetic activation, with the exit zone showing the highest sympathetic activity. These findings offer significant insights into the relationship between tunnel conditions and drivers’ physiological responses, emphasizing the importance of considering these factors in road safety and human factors engineering. By comprehending how tunnel characteristics affect drivers’ autonomic nervous system responses, we can formulate strategies to enhance driver well-being and safety.

Examining the practical importance of nonstationary cardio-respiratory coupling detection in breathing training: a methodological appraisal.

This study investigates changes in cardiorespiratory coupling during clinic breathing training and its impact on autonomic nervous functioning compared with heart rate variability (HRV). A total of 39 subjects undergoing dynamic electrocardiogram-recorded breathing training were analyzed. Subjects were divided into early- and late-training periods, and further categorized based on changes in HRV indexes. Subtypes were identified using time-frequency cardiorespiratory coupling diagrams. Significant differences were observed in the high-frequency (HF) index between training stages in the subgroup with increasing HF-HRV (p=0.0335). Both unimodal and bimodal subtypes showed significant high-frequency coupling (HFC) in the mid-training period compared with early and late stages (both p<0.0001), suggesting improved parasympathetic cardiac regulation or reduced sympathetic control. This study highlights the potential of nonstationary cardiorespiratory coupling analysis alongside traditional HRV in evaluating the therapeutic effect of breathing training on autonomic nervous function. Cardiorespiratory coupling analysis could provide valuable adjunctive information to HRV measures for assessing the impact of breathing training.

Cardiovascular responses as predictors of mortality in children with acute brain injury.

Investigate the utility of cardiovascular responses such as heart rate (HR), blood pressure (BP), and heart rate variability (HRV) in the prognosis of children with acute acquired brain injury (ABI). Children under 18 years with severe acute acquired brain injury (ABI) who survived at least 12 h after PICU admission were included in a prospective observational cohort in a tertiary academic PICU. Physiological variables, neurological data, laboratory tests (chemistry and hematology), and medications were recorded within 12 h of admission. Linear and nonlinear HRV indices, CT scans, PICU scores, and survival rates were evaluated. Seventy-two children, median age 10.7 years (IQR 4.1-13.6), were eligible for the study; 28 (38.9%) were diagnosed with brain death (BD). Tachycardia, SBP and MBP < 5th percentile, and MBP and DBP> 99th percentile were significantly associated with mortality. Poincaré SD1/SD2 was significantly associated with mortality after adjusting for age, sex and ongoing medication. Tachycardia, systolic hypotension and median hypo and hypertension were associated to mortality in children with severe ABI. While further validation through larger, multicenter studies is necessary, the Poincaré SD1/SD2 ratio has shown promise as a prognostic tool for predicting mortality in children with severe ABI. This study explores cardiovascular changes, including heart rate and blood pressure, and linear/nonlinear HRV measures using ECG at 1000 Hz, and compare them with other prognostic factors like brain tomography and PICU scores. Tachycardia, hypo/hypertension in the early hours after admission are linked to early mortality in children with severe traumatic and non-traumatic brain injury. Linear/non-linear measures of HRV were also related to survival. Higher HRV values indicating better survival chances. We identified Poincaré SD1/SD2 ratio as a promising tool for predicting mortality in children with severe ABI.

Effects of urination process on heart rate variability.

Heart rate variability (HRV) is used for the assessment of activity of the autonomic nervous system (ANS). As urination is also under the control of the ANS, this study aimed to investigate the usefulness of HRV in the assessment of ANS during the peri-urination period. The psychological effects of sitting on a chair or on the toilet during pre- and post-urination periods were also assessed. Electrocardiogram was used to measure HRV in male participants (n = 40, aged 18-30). They were allowed to drink water to ease urination. At the stage close to voiding, six measurements (each for 90s) were taken sequentially in sitting position (pre-urination chair, pre-urination toilet, urination, post-urination toilet, post-urination chair, and basal post-urination chair). HRV indices included standard deviation of R-R intervals (SDNN), root mean square of successive differences in R-R intervals (RMSSD), percentage of successive R-R intervals differing more than 50ms (pNN50), total power (TP), very-low-frequency (VLF), low-frequency (LF), and high-frequency (HF) bands together with the ratio of LF/HF. HR, SDNN, TP, LF, and LF/HF increased during urination process (P < 0.05), whereas RMSSD, pNN50, and HF increased before urination on toilet (P < 0.05) compared to sitting on a chair before and after urination. HRV indices dynamically reflected the physiological stages of urination. Parasympathetic activity (revealed by pNN50, RMSSD, and HF) increased before urination, whereas sympathovagal balance (revealed by LF/HF) increased during urination. Thus, HRV appears to be a suitable technique for studying physiological and pathological aspects of urination.

Comparison of automatic and physiologically-based feature selection methods for classifying physiological stress using heart rate and pulse rate variability indices.

This study evaluates the effectiveness of four machine Learning algorithms in classifying physiological stress using Heart Rate Variability (HRV) and Pulse Rate Variability (PRV) time series, comparing an automatic feature selection based on Akaike's criterion to a physiologically-based feature selection approach. Linear Discriminant Analysis, Support Vector Machines, K-Nearest Neighbors and Random Forest were applied on ten HRV and PRV indices from time, frequency and information domains, selected with the two feature selection approaches. Data were collected from 127 healthy individuals during different stress conditions (rest, postural and mental stress). Our results highlight that, while specific stress classification is feasible, distinguishing between postural and mental stress remains challenging. The used classifiers exhibited similar performance, with automatic Akaike Information Criterion-based feature selection proving overall better than the physiology-driven approach. Additionally, PRV-based features performed comparably to HRV-based ones, indicating their potential in outpatient monitoring using wearable devices. The obtained findings help to determine the most relevant HRV/PRV features for stress classification, potentially useful to highlight different physiological mechanisms involved during both challenges accompanied by a shift in the sympathovagal balance. The proposed approach may have implications for advancing stress assessment methodologies in clinical settings and real-world contexts for well-being evaluation.

Changes in heart rate variability and subclinical heart failure with preserved left ventricular ejection fraction in workers of the main professions at the coal industry

Introduction. The high prevalence of diseases of the circulatory system necessitates their detection and prevention at an early stage, especially in regions with high industrial potential. The occurrence of subclinical heart failure depends on a cascade of processes that are already occurring in the body and may eventually manifest themselves in clinically pronounced diseases. One of the possible mechanisms of its development is a violation of the balance of the autonomic nervous system with a violation of adaptive capabilities to the labour process, characterized by severe physical overloads among miners. The study aims to evaluate changes in heart rate variability in workers of the main professions at the coal industry with signs of heart failure with a preserved left ventricular ejection fraction. Materials and methods. The study included 78 employees of the main professions at the coal industry. Specialists performed ultrasound examination of the heart according to generally accepted methods with the study of longitudinal deformation of the myocardium. The concentration of NT-proBNP in the blood serum was determined by solid-phase enzyme immunoassay. The authors also conducted an analysis of heart rate variability, determined temporal, spectral and linear parameters. Results. Specialists revealed a decrease in longitudinal myocardial deformation in 38.5% of the examined patients, signs of diastolic dysfunction in 41%; in these groups, a tendency to increase the concentration of NT-proBNP was revealed. In the examined miners with heart failure with preserved ejection fraction, they revealed a significant decrease in the SDNN index and an increase in IC values. The increase in DFA and LF/HF indicators reflects a vegetative imbalance towards sympathetic activation observed in all surveyed miners. Limitations. This study is limited to a sample of employees of the main professions of the coal industry undergoing periodic medical examination at the Research Institute of Complex Problems of Hygiene and Occupational Diseases. Conclusion. The revealed relationship between indicators of heart failure and heart rate variability (SDNN, LF/HF, DFA and IC) in miners allows us to identify a group of people at greatest risk of adverse outcomes. Ethics. The study was conducted in compliance with the standards of the Bioethical Committee of the Research Institute of Complex Problems of Hygiene and Occupational Diseases, established in accordance with the Helsinki Declaration of the World Medical Association "Ethical Principles of Conducting medical Research with human participation as a subject" as amended in 2013 and the "Rules of Good Clinical Practice" approved by Order No. 200n of the Ministry of Health of the Russian Federation dated 04/01/2016. The subjects signed an informed consent to participate in the study.

Assessment of Cardiac Autonomic Function by Short-Term Sensor-Based and Long-Term Heart Rate Variability Analyses in Individuals with Spinal Cord Injury After Long-Term Table Tennis Training.

This study aimed to examine the acute and chronic effects of an exercising table tennis program on cardiac Autonomic Nervous System (ANS) and functional capacity in people with tetraplegia. Twenty males with tetraplegia (C6-C7), with a mean age of 38.50 ± 4.04 years old, were randomly assigned into two equal groups: A, who followed a 6-month exercise training program with table tennis 3 times per week, and B, who remained untrained. Additionally, 11 healthy sedentary men (group C) with a mean age of 39.71 ± 5.87 years old participated in the study as healthy controls. At baseline, all participants underwent a short-term (5 min) and a long-term (24 h ambulatory) ECG monitoring to evaluate the heart rate variability (HRV) indices and a maximal arm ergometric and dynamometric testing of the upper limbs. Moreover, the acute cardiac autonomic responses to maximal arm cycle exercise test were evaluated by Polar S810i sensor chest strap. At the end of the 6-month study, all parameters were revaluated only in groups A and B. At baseline, there was no statistically significant difference between the two patient groups. However, intra-group changes at the end of the 6-month study regarding the 24-h HRV monitoring indicated that group A statistically increased the standard deviation of R-R intervals (SDNN) by 13.9% (p = 0.007), the standard deviation of R-R intervals calculated every 5 min (SDANN) by 8.4% (p = 0.007), the very low frequency (VLF) by 7.1% (p = 0.042), and the low frequency [LF (ms2)] by 10.5% (p = 0.009), which almost reached the levels of group C. Favorable improvements were also noticed at the end of the study for group A in maximal exercise time of the upper limbs by 80.4% (p < 0.001) and maximal strength of the right hand by 27.8% (p < 0.001). Linear regression analysis after training showed that maximal exercise time was positively correlated with SDNN (r = 0.663, p = 0.036) and with LF (ms2) (r = 0.623, p = 0.045). Our results indicate that a 6-month table tennis training program is efficient and can improve cardiac ANS activity mainly by increasing sympathovagal balance.

Relationship between heart rate variability and echocardiography indices of cardiac function in healthy individuals.

This study evaluated the relationship between HRV and echocardiography indices of cardiac function. Healthy individuals (N = 30) aged 33 ± 10 years old, underwent short-term resting HRV assessment and transthoracic echocardiography with speckle tracking analysis. Time domain - (i.e. R-R interval, root mean square of successive RR interval difference (RMSSD), standard deviation of normal RR intervals (SDNN) and frequency domain-measures of HRV (i.e. high-frequency power (HF), low-frequency power (LF), high-frequency normalised (HFnorm) and low-frequency normalised (LFnorm)). Echocardiography indices of cardiac function included; Left ventricular ejection fraction (LVEF), left- and right-ventricular global longitudinal strain (LV-GLS, and RV GLS), left atrial strain: left atrial reservoir (LAres), left atrial conduit (LAcon) and left atrial contraction (LACT). The mean values for HRV time-domain measures were: R-R (991 ± 176 ms), SDNN (50.9 ± 21.5 ms), and RMSSD (46.8 ± 29.4 ms); and frequency-domain: LF (727 ± 606 ms2), HF (415 ± 35 ms2), LFnorm (56 ± 19.4) and HFnorm (36.5 ± 18.8). Mean values for indices of cardiac function were LVEF (59.9% ± 2.8%), LV-GLS (19.2% ± 1.4%), RV-GLS (21.7% ± 2.7%), LAres (36.8% ± 6.99%), LAcon (26.2% ± 6.95%) and LACT (12.3% ± 3.56%). There was a significant negative relationship between HF and LV-GLS (r = -0.47, p = 0.01) and RMSSD and LVEF (r = -0.39, p = 0.03) respectively. Heart rate variability measures such as high frequency power and RMSSD are associated with left ventricle systolic function in healthy individuals.

Heart Rate Variability and Heart Failure with Reduced Ejection Fraction: A Systematic Review of Literature.

Autonomic impairment is a hallmark of heart failure with reduced ejection fraction (HFrEF). While there have been studies on general values for each index of heart rate variability (HRV) analysis in HFrEF, a systematic review comprehensively examining representative values in HFrEF is lacking. We searched PubMed, Embase, and Cochrane databases to extract studies reporting representative values of HRV metrics in HFrEF. A total of 470 HFrEF patients from 6 studies were included in the review. In general, time and frequency domains were abnormally lower in HFrEF, portending a worse prognosis. In HFrEF, the mean or median value of the standard deviation of NN interval, root mean square successive difference, pNN50, and low-frequency power/high-frequency power were 40 to 121 msec, 19 to 62 msec, 1.3 to 14%, and 1.00 to 1.73, respectively. In this systematic review, most HRV metrics were found to be calculated from 24- hour Holter recordings and were lower in HFrEF patients with poor prognosis.

Дослідження впливу фаз менструального циклу на функціональний стан кваліфікованої ветеранки спорту з дзюдо

Purpose: to investigate the influence of menstrual cycle phases on the functional status of a qualified female veteran judo athlete. Material and methods. The following methods were used in the study: analysis of scientific and methodological information and Internet sources; generalization of advanced practical experience; measurement of sensorimotor reactions and determination of heart rate variability indices; methods of mathematical statistics. A qualified veteran female judo athlete (Master of Sports of Ukraine) in the age category F2 (1983-1979) took part in the study. We performed 84 measurements of heart rate variability (n=42, HRV in the supine position; n=42, heart rate variability during the test task dedicated to measuring the choice reaction). The measurement was performed using two computer programs for mobile devices running iPadOS «Research HRV» and «HRV SR+CR» during morning hours (7-8 hours) and afternoon hours (17-18 hours). Results: analysis of the dynamics of changes in heart rate variability parameters obtained in the supine position indicates an increase in sympathetic activity in the follicular phase of the menstrual cycle. Analysis of comparisons of heart rate variability parameters in different phases of the menstrual cycle indicates that the greatest number of statistically significant (p&lt;0,05) differences is observed in the first half of the day. These changes indicate the dynamics of the decrease in the tone of the sympathetic part of the autonomic nervous system in the follicular phase when performing test tasks provided by the computer program «HRV SR+CR». Analysis of the study results indicates that the indicators of heart rate variability are also influenced by the measurement conditions. The test tasks of the computer program «HRV SR+CR» provide cognitive load and concentration of attention, especially in the second stage, where it is necessary to choose the sought-after figure. During cognitive tasks there is an increase in the activity of the parasympathetic nervous system, which leads to an increase in heart rate variability. High level of heart rate variability is associated with better cognitive functions and adaptive response to stress. Consequently, these differences in heart rate variability obtained using the «Research HRV» and «HRV SR+CR» programs may be the result of interactions between physiological changes during the menstrual cycle as well as the influence of measurement conditions. Understanding the changes in heart rate variability indices during test tasks related to the manifestation of the choice reaction provides information about the influence of cognitive load and attention concentration on the functional state of the female athlete. This will allow to plan the training process of wrestling taking into account the phases of the menstrual cycle and functional capabilities that are inherent in high-skilled female athletes. Conclusions. The parameters of heart rate variability and sensorimotor reaction time provide information about the functional state of martial artists. Understanding of metabolic and hormonal processes in different phases of the menstrual cycle of qualified wrestlers will allow to optimize their training loads and recovery measures.

Cognitive Behavioral Therapy for Paroxysmal Atrial Fibrillation: Heart Rate Variability, Physical Activity, and Sleep

BackgroundCognitive behavioral therapy for symptom preoccupation in paroxysmal atrial fibrillation (AF-CBT) significantly improved AF-specific quality of life in a recent trial. To what extent this may this may be associated with changes in physiological parameters is yet to be determined. ObjectivesThe purpose of this study was to assess the effects of AF-CBT on heart rate variability (HRV), physical activity, and sleep. MethodsPatients with symptomatic paroxysmal AF on optimal medical therapy (mean ± standard deviation 65.4 ± 8.3 years, 58% females, 61% on beta-blockers) were randomized to a 10-week online AF-CBT (n = 65) or AF education (n = 62). AF-CBT was therapist-led and focused on social and physical avoidance. A 5-day Patch-Holter with an integrated accelerometer was applied at baseline, post-treatment, and at 3-month follow-up to assess AF burden, HRV, physical activity, and sleep duration. Subjective assessments were made by the International Physical Activity (IPAQ) and Insomnia Severity Index questionnaires. ResultsAt baseline, participants walked on average 8040 ± 2600 steps/day and slept 8.0 ± 1.1 hours. Objective and subjective physical activity and sleep duration remained unchanged after treatment, with no significant difference between the groups. The Insomnia Severity Index score went from subclinical insomnia (12.2 ± 6.7) to near normal values (8.1 ± 5.6), a significant change compared to controls (P = 0.032). No changes were found in AF burden or HRV indices at rest during the day or at night. ConclusionsIn this select cohort, AF-CBT decreased insomnia severity but had no impact on HRV or physical activity. Thus, AF-CBT may operate through psychological and behavioral factors that are not targeted by current medical and lifestyle interventions.

Dynamics of Respiratory Rate and Heart Rate Variability when Performing a Cognitive Task of Two Levels of Complexity

The study examined heart rate variability (HRV) and respiratory rate during a cognitive task (reading) at two difficulty levels. Time, frequency and nonlinear analysis of HRV was used. It has been shown that both some indicators of HRV (HR, SDNN, RMSSD, SD2, SD2/SD1) and respiratory rate change with increasing mental load, however, they do not separately demonstrate significant differences at all three stages of the study. Therefore, for the first time for cognitive studies, an integral indicator was used that links the parameters of the heart with respiration – the physiological cost of activity (PhysCost), which was previously used in work with athletes when they performed physical exercises to failure. Changes in the PhysCost showed that differences between a simple and a complex task are observed at all stages of the study. Thus, it has been established that the difference in the functional state of a person in the process of performing a continuous task of two levels of complexity is most reliably revealed when using an integrative indicator connecting the activity of the respiratory system and the circulatory system.

HEART RATE VARIABILITY IN OFFSPRING OF NORMOTENSIVE AND HYPERTENSIVE PARENTS: A COMPARATIVE STUDY

Objective: This study aims to evaluate the differences in heart rate variability (HRV), a biomarker of autonomic nervous system, between offspring of normotensive and hypertensive parents to understand the genetic predisposition of autonomic dysfunction. Methods: This study was a cross-sectional observational study.Two groups of healthy adults, offspring of parents with hypertension (n = 50) and offspring of parents with normal blood pressure (n = 50). Short-term HRV was measured using 5-minute electrocardiogram (ECG). HRV indices such as time and frequency domainwere measured. Data were compared by using independent t-tests, with p &lt; 0.05 being considered as statistically significant. Results:The offspring of parents with hypertension showed significantly lower HRV, with SDNN (30.5 ± 8.2 ms) compared to offspring of parents with normal blood pressure (45.2 ± 7.1 ms, p &lt; 0.001). RMSSD also was significantly lower in offspring of hypertensive group. Low-frequency (LF) power was higher in offspring of parents with hypertension,while high-frequency (HF) power was significantly reduced in them compared to the normotensive group. The LF:HF ratio was higher in offspring of parents with hypertension (2.80 ± 0.85) compared to the normotensive group (1.40 ± 0.60, p &lt; 0.001), indicating sympathovagal imbalance. Conclusion: Offspring of parents with hypertension hadlower HRV, suggesting autonomic dysfunction even in the absence of clinical hypertension. These findings emphasize the potential role of genetic predisposition in the early onset of autonomic dysregulation Further studies are required to understand mechanisms contributing to these differences in HRV.

A Cross-Sectional Study on the Effect of Stress on Short-Term Heart Rate Variability and Muscle Strength Among Construction Site Workers

This cross-sectional study investigates the immediate impact of occupational stress on short-term heart rate variability (HRV) and muscle strength among 200 construction workers in Chennai. The Perceived Stress Scale (PSS) was employed to assess stress levels, while HRV was measured using a portable ECG device, focusing on time-domain (RMSSD) and frequency-domain (HF Power) parameters. Muscle strength was evaluated using a MicroFET 2 dynamometer. Pearson correlation and multivariate regression analyses were applied to determine the associations between stress, HRV, and muscle strength, adjusting for confounding factors such as age, body mass index (BMI), and work duration. Results revealed a significant negative correlation between perceived stress and both HRV indices (RMSSD: r=-0.45, p&lt;0.01; HF Power: r=-0.50, p&lt;0.01) as well as muscle strength (r=-0.40, p&lt;0.01). Higher stress levels were associated with reduced HRV and diminished muscle strength. Regression analyses confirmed that stress independently predicted lower HRV (RMSSD: ?=-0.35, p&lt;0.01; HF Power: ?=-0.42, p&lt;0.01) and decreased muscle strength (?=-0.32, p&lt;0.01). These findings suggest that elevated stress negatively impacts both cardiovascular and muscular functioning, potentially increasing the health risks among construction workers. The study highlights the importance of implementing stress management interventions to improve both the physical well-being and productivity of workers in the construction industry.