Root Mean Square Of Successive RR Interval Differences Research Articles

Physical performance in women ́s football preseason. Body composition, heart rate and biomarkers, are they important? Rendimiento físico durante la pretemporada en fútbol femenino. Composición corporal, frecuencia cardíaca y biomarcadores, ¿son importantes?

A well-designed football pre-season is crucial for the subsequent physical performance of the players. This study aimed to analyse, in this period, the effects of body composition, heart rate variability and physiological biomar- kers on female football players’ physical performance. To this end, 22 amateur female football players (23.68 ± 3.69 years) of the same team participated in the study. Physical performance factors (acceleration capacity and jumping ability), body composition, perceived exertion load, heart rate variability and some physiological biomarkers (salivary testosterone and cortisol) were evaluated weekly during a 5-week pre-season period (from T0 to T5). Wilks’ Lambda indicated a significant F-value in all variables except the high and low heart frequency ratio (LFtoHF). Scheffe’s post-hoc identified differences between T0 and all weeks in anthropometry variables, and between T0 and T5 in all other variables. According to the regression analyses, it was revealed a negati- ve impact between percentage of body fat and physical capacities, particularly with 20-m (-13.77) and 40-m (-14.46) when the exertion is measured by the logarithm of the root mean square of successive R-R interval differences (RMSSD). Therefore, the present research suggests that amateur female football players who start the training season with a lower body fat percentage are able to achieve a better fitness level in a short period of time.

Effects of an Overnight, 8-Hour Low Oxygen Exposure on Energy Intake and Resting Energy Expenditure in Healthy, Normal Weight Adults

ObjectivesIndividuals who travel to high altitude (≥5,000 ft) are exposed to hypobaric hypoxic (HH) conditions (i.e., low pressure, low oxygen). Extended exposure to HH conditions often results in body weight loss. This body weight loss is the result of an increase in resting metabolic rate (RMR) due to alterations in the sympathetic and parasympathetic nervous system (PNS), and a decrease in energy intake due to appetite suppression. However, it is unknown if an acute bout of normobaric hypoxic (NH) exposure (i.e., normal pressure, low oxygen) at sea level induces similar changes in energy expenditure and intake. The objective of the current study was to determine the effects of a single overnight exposure to NH on RMR, heart rate variability (HRV), and energy and macronutrient intake compared to an overnight exposure to normobaric normoxia (NN) in normal-weight adults. MethodsIn this randomized crossover trial, normal-weight adults (n = 20; 22.7 ± 1.7 kg/m2, 24.5 ± 3.9 y) slept 8 h in a tent maintained at either 15% oxygen (∼8500 ft) or 20% oxygen (∼1000 ft). The following morning, HRV was measured inside the tent using electrocardiography and RMR was measured outside the tent using indirect calorimetry. Energy and macronutrient intake were assessed in the morning outside the tent with an ad-libitum breakfast buffet and a self-reported dietary record kept for the remainder of the day. ResultsOvernight oxygen saturation was lower in NH (mean ± SD: 88 ± 2%) compared to NN (96 ± 1%; P < 0.0001). Following overnight exposure to NH, RMR was elevated (1537 ± 264 kcal/d) compared to NN (1491 ± 184 kcal/d; P = 0.018. Heart rate was higher in NH (64.2 ± 10.2 bpm) compared to NN (59.7 ± 10.9 bpm; P = 0.003). PNS activity [i.e., the root mean square of successive RR interval differences (RMSSD) and high frequency activity 0.15–0.4 hz (HF)] was lower following NH (47.7 ± 19.5 ms and 524 ± 335 ms2, respectively) compared to NN (58.3 ± 22.6 ms, P = 0.034 and 748 ± 476 ms2, P = 0.052, respectively). Energy and macronutrient intake did not differ between conditions. ConclusionsOne-night exposure to NH increases RMR and reduces PNS activity without impacting energy or macronutrient intake when compared to one-night NN exposure. Future studies should evaluate whether overnight NH exposure is an effective adjunct to traditional weight loss interventions. Funding SourcesInternal funds from FSU.

0149 Reliability of Heart Rate Variability during Stable and Disrupted Polysomnographic Sleep

Abstract Introduction Heart rate variability (HRV) is a common metric to estimate autonomic activity during sleep. Frequency-domain HRV is quantified as low (LF) and high (HF) frequency, whereas HRV time-domain indices include root mean square of successive R-R interval differences (RMSSD), and percentage of successive R-R intervals differing by more than 50ms (pNN50). Despite high HRV use during sleep, it is unknown whether sleep disturbance changes overall reliability of frequency- and time-domain HRV. The purpose of this present study was to determine whether HRV was reliable across arousal-free and arousal-containing periods of sleep. Methods Twenty-seven participants (11 male, 16 female, 26±1 years, 27±1 kg/m2) were given an 8-hour sleep opportunity, equipped with continuous two-lead electrocardiography (ECG) and overnight polysomnography (PSG). The ECG recordings were analyzed via fast-Fourier transformation for frequency-domain HRV in a custom software as LF (0.04-0.15 Hz) and HF (0.15-0.4 Hz) HRV. Time-domain HRV was quantified as RMSSD and pNN50. Two separate stable sleep periods (range, 5-10min) absent of arousals were recorded, along with two separate disrupted periods of sleep with at least one arousal were selected in stage II sleep (N2), slow wave sleep (SWS), and rapid eye movement (REM) sleep. LF and HF HRV was log10 transformed due to non-normal distribution. Statistical analysis included intraclass correlations (ICC) of HRV across the four stable and disrupted periods of sleep, with separate ICC analyses across sleep stages (α = 0.05). Results Time-domain measures (RRI, RMSSD, pNN50) were reliable across arousal-free and arousal-containing sleep cycles, for all three stages (ICC&amp;gt;0.9, p&amp;lt;0.05). HF HRV exhibited similar reliability patterns across N2 sleep (ICC=0.960, p&amp;lt;0.001), SWS (ICC=0.955, p&amp;lt;0.001), and REM sleep (ICC=0.924, p&amp;lt;0.001). LF HRV was reliable in two stages of stable and disrupted sleep in N2 (ICC=0.903, p&amp;lt;0.001), REM (ICC=0.907, p&amp;lt;0.001) sleep, and trending in SWS (ICC=0.616, p=0.089) sleep. Conclusion Time- and frequency-domain HRV were reliable between stable sleep with and without cortical arousals, with the exception of LF HRV during SWS. Taken together, HRV may provide a reliable, indirect index of autonomic activity across stable and disrupted sleep. Support (If Any) Support: Support is provided by the National Institutes of Health (AA-024892; U54GM115371; P20GM103474).

The effect of regular physical training on heart rate variability in healthy male volunteers

Abstract Funding Acknowledgements Type of funding sources: None. Background The autonomic nervous system's responses are reflected in heart rate variability (HRV). They have a significant role in accompanying the training process, however, assessment of long-term daily HRV indices dynamics is not widely used in sports cardiology. Purpose To determine if there are variations in long-term responses of autonomic regulation of cardiac activity to regular systematic training. Methods In this prospective study, we included 28 healthy men aged 18-19 years who had a repeated 24-hour Ambulatory ECG monitoring between February 2018 and December 2019 (Figure 1). The subjects were in similar working and living conditions. The training regimen consisted of moderate to vigorous physical activity for 270 (SD 40) minutes per week (total 100 weeks of follow-up). The subjects were divided into groups according to the median of changes in assessment results for various types of physical training (Table 1): with the maximum and minimum positive dynamics of physical fitness in endurance (3000m race), speed (100m race), strength (pull-ups on the horizontal bar). 24-hour Holter was performed using a wearable ECG device. HRV parameters at the beginning and at the end of the study in groups with the maximum positive physical fitness dynamics were compared. To assess HRV, the following daily time-domain indices were used: RMSSD (root mean square of successive RR interval differences), pNN50% (percentage of successive RR intervals that differ by more than 50 ms) and SDANN (standard deviation of the averages of the NN intervals in all 5 min segments of the entire recording). Results The initial mean heart rate in groups 1-6 did not differ significantly across repeated heart rate monitoring (Table 1). In group 1, the improvement in endurance exercise performance directly correlated with changes in RMSSD (rs = 0.297, p &amp;lt;0.05) and pNN50% (rs = 0.448, p &amp;lt;0.05). In group 3, increased fitness in short distance running was accompanied by a decrease in the values of the RMSSD (rs = –0.211, p &amp;lt;0.05) and pNN50% (rs = –0.539, p &amp;lt;0.05) and an increase in the values of the SDANN (rs = 0.352, p &amp;lt; 0.05). In group 5, increased fitness in strength exercises was accompanied by a balanced increase in pNN50% (rs = 0.371, p &amp;lt;0.05), RMSSD (rs = 0.347, p &amp;lt;0.05), as well as SDANN (rs = 0.440, p &amp;lt;0,05). In groups 2, 4, 6, there were similar but weaker associations. Conclusion Systematic training is associated with significant changes in the autonomic regulation of heart rate. An increase in fitness in sprint distance running results in a decrease in daily parasympathetic and an increase in sympathetic activity on the heart. Increased fitness in strength exercises is associated with increase in both sympathetic and parasympathetic activity. While an increase in endurance is accompanied by an increase in the activity of the parasympathetic limb of the autonomic nervous system.

Heart Rate Variability during Auricular Acupressure at Heart Point in Healthy Volunteers: A Pilot Study.

Heart rate variability (HRV) is the variation in time between each heartbeat. Increasing HRV may contribute to improving autonomic nervous system dysfunctions. Acupuncture stimulation through the vagus plexus in the ear is considered as a method that can improve HRV. In this pilot study, we examined 114 healthy volunteers at the Faculty of Traditional Medicine, University of Medicine and Pharmacy at Ho Chi Minh City, from January to May 2020. During a 20-minute interval, participants were stimulated two times at the acupoint in the left ear with Semen seed. The heart rate and HRV values were monitored before, during, and after acupressure every 5 minutes. When we compared the experimental group with the control group, HRV significantly increased in the stage of ear-stimulated acupressure compared with the stage before and after the auricular acupressure (p=0.01, p=0.04, p=0.04 and p=0.02) and the difference was not statistically significant compared with the phase of nonstimulated (p=0.15, p=0.28). The changes in other values including SDNN (standard deviation of the average NN), RMSSD (root mean square of successive RR interval differences), LF (low-frequency power), and HF (high-frequency power) in all stages were not statistically significant (p=>0.05) between groups. Based on the results, we can determine the increase in HRV when conducting auricular acupressure with stimulation at the heart acupoint on the left ear. This leads to a direction in further studies for clinical application for patients with autonomic nervous disorder.

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.

Heart rate variability and cardiac autonomic functions in post-COVID period.

BackgroundThe heart rate variability (HRV) is a non-invasive, objective and validated method for the assessment of autonomic nervous system. Although acute manifestations of COVID-19 were widely researched, long-term sequela of COVID-19 are still unknown. This study aimed to analyze autonomic function using HRV indices in the post-COVID period that may have a potential to enlighten symptoms of COVID long-haulers.MethodsThe 24-h ambulatory electrocardiography (ECG) recordings obtained >12 weeks after the diagnosis of COVID-19 were compared with age–gender-matched healthy controls. Patients who used drugs or had comorbidities that affect HRV and who were hospitalized with severe COVID-19 were excluded from the study.ResultsTime domain indices of HRV analysis (standard deviation of normal RR intervals in 24 h (SDNN 24 h) and root mean square of successive RR interval differences (RMSSD)) were significantly higher in post-COVID patients (p < 0.05 for all). Among frequency domain indices, high frequency and low frequency/high frequency ratio was significantly higher in post-COVID patients (p = 0.037 and p = 0.010, respectively). SDNN >60 ms [36 (60.0%) vs. 12 (36.4%), p = 0.028)] and RMSSD >40 ms [31 (51.7%) vs. 7 (21.2%), p = 0.003)] were more prevalent in post-COVID patients. Logistic regression models were created to evaluate parasympathetic overtone in terms of SDNN >60 ms and RMSSD >40 ms. After covariate adjustment, post-COVID patients were more likely to have SDNN >60 msn (OR: 2.4, 95% CI:1.2–12.8) and RMSSD >40 ms (OR: 2.5, 95% CI: 1.4–9.2).ConclusionThis study revealed parasympathetic overtone and increased HRV in patients with history of COVID-19. This may explain the unresolved orthostatic symptoms occurring in post-COVID period which may be associated with autonomic imbalance.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10840-022-01138-8.

Heart Rate Variability on 10-Second Electrocardiogram and Risk of Acute Exacerbation of COPD: A Secondary Analysis of the BLOCK COPD Trial.

Autonomic dysfunction is common in chronic obstructive pulmonary disease (COPD), and worse autonomic function may be a marker of risk for acute exacerbations of COPD (AECOPD). Heart rate variability (HRV) is a measure of autonomic function. Our objective was to test whether lower (worse) HRV is a risk factor for AECOPD. We measured standard deviation of normal RR intervals (SDNN) and root mean square of successive RR interval differences (RMSSD) on 10-second electrocardiograms (ECGs) performed at screening and day 42 in participants in the Beta Blockers for the Prevention of Acute Exacerbations of COPD trial ( BLOCK-COPD), a placebo-controlled trial of metoprolol for prevention of AECOPD. We used Cox-proportional hazards models to test if these HRV measures were associated with risk of any AECOPD, and separately, hospitalized AECOPD. We tested associations using baseline HRV measures and incorporating HRV measures from day 42 as a time-varying covariate. We also tested for interactions with metoprolol assignment. Of 532 trial participants, 529 (forced expiratory volume in 1 second [FEV1 ]41 ± 16.3 % predicted) were included in this analysis. We did not find a significant association between HRV measures and risk of AECOPD when all participants were analyzed together. There was a significant interaction between RMSSD and assignment to metoprolol on time to first hospitalized AECOPD; in the placebo group greater RMSSD was associated with a lower risk of hospitalized AECOPD (adjusted hazard ratio0.71, 95% confidence interval: 0.52 to 0.96, per 10 ms increase) but there was no association in the metoprolol group. Autonomic dysfunction as measured by HRV may be a risk factor for AECOPD. Future studies should analyze longer HRV recordings and their performance in broader samples of people with COPD, including those on beta-blockers.

Effect of Intensity on Changes in Cardiac Autonomic Control of Heart Rate and Arterial Stiffness After Equated Continuous Running Training Programs.

Background: It is well known that exercise training has positive effects on both cardiac autonomic function and arterial stiffness (AS). However, it is not clear that which exercise training variables, intensity or volume, or both, play a crucial role in this regard. This study investigates the chronic effects of high-volume moderate-intensity training (HVMIT) and low-volume high-intensity training (LVHIT) on heart rate variability (HRV) and AS in sedentary adult men.Materials and Methods: Notably, 45 males (age: 42 ± 5.7 years) were randomly assigned to a control (n = 15), HVMIT (n = 15), or LVHIT (n = 15). The HVMIT group ran three times per week on a treadmill at 50–60% of VO2max for 45–60 min, while the LVHIT trained at 70–85% of VO2max for 25–40 min. Both training protocols were equated by caloric expenditure. HRV, pulse wave velocity (PWV), hemodynamic variables, and body composition were measured before and after 12 weeks.Results: Both protocols (i.e., HVMIT and LVHIT) significantly increased the SD of normal sinus beat intervals (SDNN) and high-frequency (HF) bands (p < 0.05) after 12 weeks. Whereas the low-frequency (LF)-HF ratio decreased significantly in both training protocols (p < 0.05); however, these changes were significantly greater in the LVHIT protocol (p < 0.05). Furthermore, the root mean square of successive RR interval differences (RMSSD) significantly increased only in the LVHIT (p < 0.05). Moreover, a significant decrease in LF and PWV was only observed following the LVHIT protocol (p < 0.05). Some measures of HRV and PWV were significantly correlated (r = 0.275–0.559; p < 0.05).Conclusion: These results show that the LVHIT protocol was more efficient for improving HRV variables and PWV than the HVMIT protocol after 12 weeks of continuous running training. Interestingly, changes in some HRV parameters were related to changes in PWV. Further studies should elaborate on the link between central and peripheral cardiovascular adaptations after continuous and intermittent training regimens differing in intensity.

The effect of spinal manipulative therapy and home stretching exercises on heart rate variability in patients with persistent or recurrent neck pain: a randomized controlled trial

BackgroundPersistent or recurrent neck pain is, together with other chronic conditions, suggested to be associated with disturbances of the Autonomic Nervous System. Acute effects on the Autonomic Nervous System, commonly measured using Heart Rate Variability, have been observed with manual therapy. This study aimed to investigate the effect on Heart Rate Variability in (1) a combination of home stretching exercises and spinal manipulative therapy versus (2) home stretching exercises alone over 2 weeks in participants with persistent or recurrent neck pain.MethodsA randomized controlled clinical trial was carried out in five multidisciplinary primary care clinics in Stockholm from January 2019 to April 2020. The study sample consisted of 131 participants with a history of persistent or recurrent neck. All participants performed home stretching exercises daily for 2 weeks and were scheduled for four treatments during this period, with the intervention group receiving spinal manipulative therapy in addition to the home exercises. Heart Rate Variability at rest was measured at baseline, after 1 week, and after 2 weeks, with RMSSD (Root mean square of successive RR interval differences) as the primary outcome. Both groups were blinded to the other group intervention. Thus, they were aware of the purpose of the trial but not the details of the “other” intervention. The researchers collecting data were blinded to treatment allocation, as was the statistician performing data analyses. The clinicians provided treatment for participants in both groups and could not be blinded. A linear mixed-effects model with continuous variables and person-specific random intercept was used to investigate the group-time interaction using an intention to treat analysis.ResultsSixty-six participants were randomized to the intervention group and sixty-five to the control group. For RMSSD, a B coefficient of 0.4 (p value: 0.9) was found, indicating a non-significant difference in the regression slope for each time point with the control group as reference. No statistically significant differences were found between groups for any of the Heart Rate Variability indices.ConclusionAdding four treatments of spinal manipulation therapy to a 2-week program of daily stretching exercises gave no significant change in Heart Rate Variability.Trial Registration: The trial was registered 03/07/2018 at ClinicalTrials.gov, registration number: NCT03576846. (https://pubmed.ncbi.nlm.nih.gov/31606042/)

Heart Rate Variability in Insulo-Opercular Epilepsy.

Background: We aimed to evaluate heart rate variability (HRV) changes in insulo-opercular epilepsy (IOE) and after insulo-opercular surgery. Methods: We analyzed 5-min resting HRV of IOE patients before and after surgery. Patients’ SUDEP-7 risk inventory scores were also calculated. Results were compared with age- and sex-matched patients with temporal lobe epilepsy (TLE) and healthy individuals. Results: There were no differences in HRV measurements between IOE, TLE, and healthy control groups (and within each IOE group and TLE group) in preoperative and postoperative periods. In IOE patients, the SUDEP-7 score was positively correlated with pNN50 (percentage of successive RR intervals that differ by more than 50 ms) (p = 0.008) and RMSSD (root mean square of successive RR interval differences) (p = 0.019). We stratified IOE patients into those whose preoperative RMSSD values were below (Group 1a = 7) versus above (Group 1b = 9) a cut-off threshold of 31 ms (median value of a healthy population from a previous study). In group 1a, all HRV values significantly increased after surgery. In group 1b, time-domain parameters significantly decreased postoperatively. Conclusions: Our results suggest that in IOE, HRV may be either decreased in parasympathetic tone or increased globally in both sympathetic and parasympathetic tones. We found no evidence that insulo-opercular surgeries lead to major autonomic dysfunction when a good seizure outcome is reached. The increase in parasympathetic tone observed preoperatively may be of clinical concern, as it was positively correlated with the SUDEP-7 score.

Directional effects of whole-body spinning and visual flow in virtual reality on vagal neuromodulation.

Neural circuits allow whole-body yaw rotation to modulate vagal parasympathetic activity, which alters beat-to-beat variation in heart rate. The overall output of spinning direction, as well as vestibular-visual interactions on vagal activity still needs to be investigated. This study investigated direction-dependent effects of visual and natural vestibular stimulation on two autonomic responses: heart rate variability (HRV) and pupil diameter. Healthy human male subjects (n = 27) underwent constant whole-body yaw rotation with eyes open and closed in the clockwise (CW) and anticlockwise (ACW) directions, at 90°/s for two minutes. Subjects also viewed the same spinning environments on video in a VR headset. CW spinning significantly decreased parasympathetic vagal activity in all conditions (CW open p = 0.0048, CW closed p = 0.0151, CW VR p = 0.0019,), but not ACW spinning (ACW open p = 0.2068, ACW closed p = 0.7755, ACW VR p = 0.1775,) as indicated by an HRV metric, the root mean square of successive RR interval differences (RMSSD). There were no direction-dependent effects of constant spinning on sympathetic activity inferred through the HRV metrics, stress index (SI), sympathetic nervous system index (SNS index) and pupil diameter. Neuroplasticity in the CW eyes closed and CW VR conditions post stimulation was observed. Only one direction of yaw spinning, and visual flow caused vagal nerve neuromodulation and neuroplasticity, resulting in an inhibition of parasympathetic activity on the heart, to the same extent in either vestibular or visual stimulation. These results indicate that visual flow in VR can be used as a non-electrical method for vagus nerve inhibition without the need for body motion in the treatment of disorders with vagal overactivity. The findings are also important for VR and spinning chair based autonomic nervous system modulation protocols, and the effects of motion integrated VR.

Heart rate variability and incident type 2 diabetes mellitus

Abstract Background Hyperglycemia and autonomic dysfunction are bidirectionally related. The implications from former cross-sectional studies regarding the association of autonomic dysfunction and diabetes are limited due to the potential reverse causation. We aimed to investigate the association of longitudinal evolution of heart rate variability (HRV) with incident type 2 diabetes mellitus (T2D) among the general population. Methods Using data from the prospective population-based cohort study, 7630 participants with available repeated assessments of HRV, who were free of T2D and atrial fibrillation, were included. Measurements of HRV were analyzed from standard 10-s electrocardiograms records, including heart rate and two time-domain HRV markers: the heart-rate corrected standard deviation of the normal-to-normal RR intervals (SDNNc) and heart-rate corrected root mean square of successive RR-interval differences (RMSSDc). Joint models with the Bayes approach were performed to assess the associations between longitudinal evolutions of heart rate and different HRV metrics with incident T2D during follow-up. Models were adjusted for age, sex, body mass index, smoking status, systolic blood pressure, total and high-density lipoprotein cholesterol, use of blood pressure-lowering or lipid-lowering medication, and prevalent cardiovascular disease. Spearmen correlation was used to examine the associations between HRV metrics and glycemic traits (fasting blood glucose, insulin, and homeostatic model assessment of insulin resistance (HOMA-IR) and beta-cell function (HOMA-β)) at baseline. Results During a median follow-up time of 8.6 years, 871 individuals developed T2D. Based on joint models, one standard deviation (SD) increment of heart rate (hazard ratio [HR], 1.21; 95% CI, 1.09–1.34), log(SDNNc) (HR, 1.10; 95% CI, 0.94–1.27), and log(RMSSDc) (HR, 1.15; 95% CI, 1.02–1.31) was associated with the risk of developing T2D in fully-adjusted models. Subgroup analyses suggested stronger associations among men. The HRs of incident T2D per SD increment were 1.25 (1.09, 1.43) for men and 1.16 (0.99, 1.35) for women for heart rate, 1.23 (1.01, 1.51) for men and 0.97 (0.78, 1.20) for women for log(SDNNc), and 1.24 (1.05, 1.48) for men and 1.09 (0.89, 1.31) for women for log(RMSSDc). Results did not change after excluding participants who were prediabetes at baseline or after exclusion of underweight participants. Spearmen correlation indicated that heart rate was significantly associated with baseline glycemic traits, while RMSSDc was only related to fasting blood glucose. Conclusion Our study suggests that both higher heart rate and heart rate variability are associated with an increased risk of T2D development, especially among men. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Erasmus MC and Erasmus University Rotterdam; Netherlands Organization for Scientific Research; Netherlands Organization for Health Research and Development (ZonMw); Research Institute for Diseases in the Elderly; Netherlands Genomics Initiative; Netherlands Ministry of Education, Culture and Science; Netherlands Ministry of Health, Welfare and Sports; European Commission; and Municipality of Rotterdam. We would like to thank the China Scholarship Council for the scholarship to K.W. Forest plot

Использование нелинейных параметров вариабельности сердечного ритма для выявления стресса

This paper presents a stress detection algorithm using heart rate variability (HRV) parameters. Five-minute electrocardiograms were recorded at rest and under exam stress (252 students were involved). The determined HRV parameters were applied to detect stress by means of several classification algorithms. We analysed linear indices in the time (standard deviation of NN intervals (SDNN) and root mean square of successive RR interval differences (RMSSD)) and frequency domains (low frequency (LF) and high frequency (HF) power as well as LF/HF ratio). To study nonlinear HRV indices, we evaluated approximate entropy (ApEn), sample entropy (SampEn), α1 (DFA1) and α2 (DFA2) scaling exponents, correlation dimension D2, and recurrence plot quantification measures (recurrence rate (REC), mean diagonal line length (Lmean), maximum diagonal line length (Lmax), determinism (DET), and Shannon entropy (ShanEn)). Receiver operating characteristic (ROC) was used to test the performance of the classifiers derived from HRV. The highest area under the ROC curve (AUC), sensitivity, and specificity were found for mean RR-interval, DFA1, DFA2, RMSSD, and Lmax. These parameters were used for stress/rest classification with the help of algorithms that are common in clinical and physiological applications, i.e. logistic regression (LR) and linear discriminant analysis (LDA). Classification performance for stress was quantified using accuracy, sensitivity and specificity measures. The LR achieved an accuracy of 68.25 % at an optimal cutoff value of 0.57. LDA determined stress with 67.46 % accuracy. Thus, HRV parameters can serve as an objective tool for stress detection.

HEART RATE VARIABILITY ON 10-SECOND ECG AND RISK OF ACUTE EXACERBATIONS OF COPD: A SECONDARY ANALYSIS OF BLOCK COPD

HEART RATE VARIABILITY ON 10-SECOND ECG AND RISK OF ACUTE EXACERBATIONS OF COPD: A SECONDARY ANALYSIS OF BLOCK COPD

Heart Rate Variability During Physical Exercise Is Associated With Improved Cognitive Performance in Alzheimer's Dementia Patients-A Longitudinal Feasibility Study.

Heart rate variability (HRV) rapidly gains attention as an important marker of cardiovascular autonomic modulation. Moreover, there is evidence for a link between the autonomic deficit measurable by reduced HRV and the hypoactivity of the cholinergic system, which is prominently affected in Alzheimer's disease (AD). Despite the positive influence of physical exercise on cognition and its promising association with HRV, previous studies did not explore the effect of long-term physical exercise in older adults with AD. Taking advantage of a longitudinal study we analyzed the effect of a 20-week dual task training regime (3 × 15-min per week) on the vagal mediated HRV index RMSSD (root mean square of successive RR interval differences) during physical exercise and the short-term memory performance in a AD cohort (N = 14). Each training contained physical exercise on a bicycle ergometer while memorizing 30 successively presented pictures as well as the associated post-exercise picture recognition memory test. Linear-mixed modeling revealed that HRV-RMSSD significantly increased over the intervention time. Moreover, the reaction time in the picture recognition task decreased while the accuracy remained stable. Furthermore, a significantly negative relationship between increased fitness measured by HRV-RMSSD and decreased reaction time was observed. This feasibility study points to the positive effects of a dual task regime on physical and cognitive fitness in a sample with impaired cognitive performance. Beyond this, the results show that the responsiveness of parasympathetic system as measured with HRV can be improved in patients with dementia.

89 Learning ability and physiological stress response of horses (Equus caballus) undergoing discrimination and reversal learning tasks using a touch screen

The objective of this study was to evaluate the cognitive abilities and physiological stress responses of horses ( Equus caballus ) undergoing discrimination and reversal learning tasks using a touch screen powered by a computer. Utilizing such technology to present stimuli and collect data points provided standardization across all test subjects, and removed human error and bias from the experimentation. The study population consisted of 9 horses and ponies, all managed similarly at the same facility. The horses, 5 mares and 4 geldings, were aged 10–23 years (mean 14.8, ± 3.03). These 9 subjects were tested on discrimination learning based on their ability to select a pre-determined 2-dimensional shape (black circle or triangle) and their performance measured as a percentage of correct responses within a given session. Latency to touch the screen was also recorded, in seconds. Once this task was acquired, as determined by completing 2 consecutive sessions at ≥ 80% performance, the horses were then tested on reversal learning by switching the previously-rewarded shape to the unrewarded one, and the previously-unrewarded shape to the rewarded one. Before any experimentation began, horses were habituated to the experimental environment and shaped to touch the screen with their muzzles. Positive reward in the form of food was the only reinforcement method used throughout the study. The following physiological stress variables were recorded during all sessions by Polar H10 Heart Rate Sensors: standard deviation of NN intervals (SDNN), root mean square of successive rr-interval differences (RMSSD), and the ratio of low frequency to high frequency (LF/HF). Statistical analysis was performed using Spearman rank correlation coefficients to assess the potential relationships between performance, latency, and any of the stress variables. Results showed that performance and latency were positively correlated in both discrimination and reversal learning ( P < 0.001, Spearman's rho = 0.358, α = 0.05 and P < 0.001, and Spearman's rho = 0.512, α = 0.05, respectively). No significant correlation was found between either performance or latency and SDNN, RMSSD, or LF/HF. These results suggest that making comparatively slow, deliberate choices were linked to a higher performance.

Cardiac Autonomic Dysfunction and Risk of Sudden Unexpected Death in Epilepsy.

We aimed to test whether patients who died of sudden unexpected death in epilepsy (SUDEP) had an abnormal cardiac autonomic response to sympathetic stimulation by hyperventilation. We conducted a retrospective, observational, case-control study of a group of patients who died of SUDEP and controls who were matched to the patients for epilepsy type, drug resistance, sex, age at EEG recording, age at onset of epilepsy, and duration of epilepsy. We analyzed the heart rate (HR) and HR variability (HRV) at rest and during and after hyperventilation performed during the patient's last EEG recording before SUDEP. In each group, changes over time in HRV indexes were analyzed with linear mixed models. Twenty patients were included in each group. In the control group, the HR increased and the root mean square of successive RR-interval differences (RMSSD) decreased during the hyperventilation and then returned to the baseline values. In the SUDEP group, however, the HR and RMSSD did not change significantly during or after hyperventilation. A difference in HR between the end of the hyperventilation and 4 minutes after its end discriminated well between patients with SUDEP and control patients (area under the receiver operating characteristic curve 0.870, sensitivity 85%, specificity 75%). Most of patients with subsequent SUDEP have an abnormal cardiac autonomic response to sympathetic stimulation through hyperventilation. An index reflecting the change in HR on hyperventilation might be predictive of the risk of SUDEP and could be used to select patients at risk of SUDEP for inclusion in trials assessing protective measures.

Activation of the cholinergic antiinflammatory reflex by occipitoatlantal decompression and transcutaneous auricular vagus nerve stimulation.

The parasympathetic-mediated inflammatory reflex inhibits excessive proinflammatory cytokine production. Noninvasive techniques, including occipitoatlantal decompression (OA-D) and transcutaneous auricular vagus nerve stimulation (taVNS), have been demonstrated to increase parasympathetic tone. To test the hypothesis that OA-D and taVNS increase parasympathetic nervous system activity and inhibit proinflammatory cytokine mobilization and/or production. Healthy adult participants were randomized to receive OA-D (5min of OA-D followed by 10min of rest; n=8), taVNS (15min; n=9), or no intervention (15min, time control; n=10) on three consecutive days. Before and after these interventions, saliva samples were collected for determination of the cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor α (TNF-α). Arterial blood pressure and the electrocardiogram were recorded for a 30-min baseline, throughout the intervention, and during a 30-min recovery period to derive heart rate and blood pressure variability markers as indices of vagal and sympathetic control. OA-D and taVNS increased root mean square of successive RR interval differences (RMSSD) and high frequency heart rate variability, which are established markers for parasympathetic modulation of cardiac function. In all three groups, the experimental protocol was associated with a significant increase in salivary cytokine concentrations. However, the increase in IL-1β was significantly less in the taVNS group (+66±13pg/mL; p<0.05) than in the time control group (+142±24pg/mL). A similar trend was observed in the taVNS group for TNF-α (+1.7±0.3pg/mL vs. 4.1±1.3pg/mL; p<0.10). In the OA-D group baseline IL-6, IL-8, and TNF-α levels on the third study day were significantly lower than on the first study day (IL-6: 2.3±0.4 vs. 3.2±0.6pg/mL, p<0.05; IL-8: 190±61 vs. 483±125pg/mL, p <0.05; TNF-α: 1.2±0.3 vs. 2.3±0.4pg/mL, p<0.05). OA-D decreased mean blood pressure from the first (100±8mmHg) to the second (92±6mmHg; p<0.05) and third (93±8mmHg; p<0.05) study days and reduced low frequency spectral power of systolic blood pressure variability (19±3mmHg2 after OA-D vs. 28±5mmHg2 before OA-D; p<0.05), a marker of sympathetic modulation of vascular tone. OA-D also increased baroreceptor-heart rate reflex sensitivity from the first (13.7±3.0ms/mmHg) to the second (18.4±4.3ms/mmHg; p<0.05) and third (16.9±4.2ms/mmHg; p<0.05) study days. Both OA-D and taVNS elicited antiinflammatory responses that were associated with increases in heart rate variability-derived markers for parasympathetic function. These findings suggest that OA-D and taVNS activate the parasympathetic antiinflammatory reflex. Furthermore, an antihypertensive effect was observed with OA-D that may be mediated by reduced sympathetic modulation of vascular tone and/or increased baroreceptor reflex sensitivity.

Abstract 13369: Sympathovagal Imbalance Decades After Atrial Septal Defect Repair

Introduction: Heart rate variability (HRV), a measure of the autonomic nervous system activity, is a morbidity and mortality predictor. HRV is decreased in children with atrial septal defects (ASD) indicating parasympathetic withdrawal and sympathetic predominance, and increased right atrial end-diastolic pressure is believed to influence the sympathovagal balance. Despite the belief of a benign long-term outcome after closure, ASD patients have increased mortality rates after the age of 30 yrs. This may correlate to HRV, why we study HRV in adults after closure. Hypothesis: ASD patients have impaired HRV after closure when compared with controls. Methods: Surgically closed ASD patients (n=17, mean age 32±9 yrs., mean time since closure 19±8 yrs.), percutaneously closed ASD patients (n=18, mean age 28±7 yrs., mean time since closure 15±5 yrs.) and age- and gender-matched controls (n=15, mean age 30±9 yrs.) underwent a 48-hr Holter monitoring. Inclusion criteria were an age of minimum 2 yrs. at the time of diagnosis and minimum 3 yrs. must have passed since ASD closure. The following time-domain HRV measures were analyzed: SD of NN intervals (SDNN), SD of the average NN interval for each 5-minute segment, mean of the SDs of all NN intervals for each 5-minute (SDNNi), root mean square of successive RR interval differences (RMSSD), percentage of successive RR intervals that differ by &gt;50 ms (pNN50), and triangular index. Results: Surgically closed ASD patients have an impairment of all time-domain parameters, while transcatheter closed patients have an impairment of half the parameters. Conclusion: These novel findings demonstrate a cardiac sympathovagal imbalance in adult patients several yrs. after ASD closure and may potentially explain why we observe a long-term morbidity and mortality increase in ASD patients.