Heart Rate Variability In Subjects Research Articles

Prediction of Impulsive Aggression Based on Video Images.

In response to the subjectivity, low accuracy, and high concealment of existing attack behavior prediction methods, a video-based impulsive aggression prediction method that integrates physiological parameters and facial expression information is proposed. This method uses imaging equipment to capture video and facial expression information containing the subject's face and uses imaging photoplethysmography (IPPG) technology to obtain the subject's heart rate variability parameters. Meanwhile, the ResNet-34 expression recognition model was constructed to obtain the subject's facial expression information. Based on the random forest classification model, the physiological parameters and facial expression information obtained are used to predict individual impulsive aggression. Finally, an impulsive aggression induction experiment was designed to verify the method. The experimental results show that the accuracy of this method for predicting the presence or absence of impulsive aggression was 89.39%. This method proves the feasibility of applying physiological parameters and facial expression information to predict impulsive aggression. This article has important theoretical and practical value for exploring new impulsive aggression prediction methods. It also has significance in safety monitoring in special and public places such as prisons and rehabilitation centers.

Heart Rate Variability in Subjects with Severe Allergic Background Undergoing COVID-19 Vaccination

Anti-Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) vaccination is the world's most important strategy for stopping the pandemic. Vaccination challenges the body's immune response and can be complicated by hypersensitivity reactions. The autonomic nervous system can modulate the inflammatory immune response, therefore constituting a potential marker to characterize individuals at high risk of hypersensitivity reactions. Autonomic nervous system functionality was assessed through measurement of the heart rate variability (HRV) in subjects with a history of severe allergic reactions and 12 control subjects. HRV parameters included the mean electrocardiograph RR interval and the standard deviation of all normal R-R intervals (SDNN). All measurements were performed immediately before the anti-SARS-CoV-2 vaccination. The median RR variability was lower in the study than in the control group: 687 ms (645-759) vs. 821 ms (759-902); p = 0.02. The SDNN was lower in the study group than in the control group: 32 ms (23-36) vs. 50 ms (43-55); p < 0.01. No correlation was found between age and the SDNN. Autonomic nervous system activity is unbalanced in people with a severe allergy background.

COVID-19 and the autonomic nervous system

Abstract Background COVID-19 infection has been shown to have an adverse impact on the cardiovascular system. Cardiac injury, as indicated by elevated cardiac troponin and NT-proBNP levels have been confirmed in COVID-19 cases. There is still ambivalent data on the effect of left ventricular function. Cases of left ventricular impairment, persistent hypotension, acute myopericarditis, myocarditis, arrhythmia and heart failure have been reported in the short term, but there is a significant lacuna when it comes to medium and long-term follow-up of subjects previously infected with COVID-19. Purpose To assess any residual myocardial and autonomic injury in subjects previously infected with COVID-19 at a median follow-up of 5 months. Methods A case-control study was performed. Cases were randomly selected subjects who were previously diagnosed with COVID-19 infection following nasopharyngeal swabbing. Controls were subjects who had not been found to be infected with COVID-19 following swabbing and were negative for COVID-19 IgG antibodies. All participants were submitted a standardised questionnaire regarding past medical history. Blood investigations were taken including NT-proBNP and troponin I levels. In addition, all participants underwent 24-hour ambulatory blood pressure monitoring (ABPM) and 24-hour ECG monitoring. The latter was used to assess both for underlying arrhythmias as well as heart rate variability (HRV), a measure of autonomic regulation of the heart. All data was analysed using SPSS version 23.0. Results The study comprised 259 subjects, whereby cases included 174 participants while 75 subjects were age- and gender-matched controls. The study cohort was relatively young with a mean age of 46.1±13.8 years. The median follow-up was of approximately 5 months (median 173.5 days, IQR 129–193.25 days). There was no statistically significant difference between cases and controls with regards cardiovascular risk factors and underlying medical conditions. Likewise, there was no difference in blood investigations, including troponin I and NT-proBNP levels at 5-months follow-up. No difference was noted between the two groups in both awake and asleep blood pressure (BP) readings, as well as dipping BP status. No significant arrhythmias were noted in both groups on 24-hour ECG monitoring. However, when assessing for heart rate variability, it was shown that subjects who had been previously infected with COVID-19 exhibited lower root-mean square differences of successive R-R intervals (RMSSD), p=0.028. This indicates poor vagus nerve-mediated autonomic control of the heart. Conclusion Subjects previously infected with COVID-19 exhibited lower HRV as exhibited by low RMSSD as compared to controls. Reduced HRV is a known biomarker for mortality and sudden death in cardiac disease. The possible long-term implications of reduced HRV in subjects previously infected with COVID-19 merits further investigation. Funding Acknowledgement Type of funding sources: None.

The Predictive Value of Serum Calcium on Heart Rate Variability and Cardiac Function in Type 2 Diabetes Patients.

BackgroundCardiovascular autonomic neuropathy (CAN) is common in patients with type 2 diabetes mellitus (T2DM), mainly presented as decreased heart rate variability (HRV) which often leads to cardiac death. However, HRV measurement is not convenient in most clinics. Therefore, identifying high-risk patients for CAN in diabetes with easier measurements is crucial for the early intervention and prevention of catastrophic consequences.MethodsIn this cross-sectional study, 675 T2DM patients with normocalcemia were selected. Of these, they were divided into two groups: normal HRV group (n = 425, 100 ms≤ SDNN ≤180 ms) vs. declined HRV group (n = 250, SDNN <100 ms). All patients’ clinical data were collected and the correlation of clinical variables with HRV were analyzed by correlation and logistic regression analysis. The area below the ROC curve was used to evaluate the predictive performance of serum calcium on HRV.ResultsIn this study, declines in HRV were present in 37.0% of T2DM patients. Significant differences in albumin-adjusted serum calcium levels (CaA) (8.86 ± 0.27 vs. 9.13 ± 0.39 mg/dl, p <0.001) and E/A (0.78 ± 0.22 vs. 0.83 ± 0.26, p = 0.029) were observed between declined HRV and normal HRV groups. Bivariate linear correlation analysis showed that CaA and E/A were positively correlated with HRV parameters including SDNN (p < 0.001), SDNN index (p < 0.001), and Triangle index (p < 0.05). The AUC in the ROC curve for the prediction of CaA on HRV was 0.730 (95% CI (0.750–0.815), p < 0.001). The cutoff value of CaA was 8.87 mg/dl (sensitivity 0.644, specificity 0.814). The T2DM patients with CaA <8.87 mg/dl had significantly lower HRV parameters (SDNN, SDNN index, rMSSD, and triangle index) than those with CaA ≥8.87 mg/dl (p < 0.01, respectively). Multivariate logistic regression analysis showed a significantly increased risk of declined HRV in subjects with CaA level <8.87 mg/dl [OR (95% CI), 0.049 (0.024–0.099), p < 0.001].ConclusionsDeclined HRV is associated with a lower CaA level and worse cardiac function. The serum calcium level can be used for risk evaluation of declined HRV in T2DM patients even within the normocalcemic range.

Altered cardiac autonomic function after recovery from COVID-19.

BackgroundAutonomic dysfunction may occur during the acute phase of COVID‐19. Heart rate variability (HRV) is a useful tool for the assessment of cardiac sympathetic and parasympathetic balance. We aimed to evaluate cardiac autonomic function by using HRV in subjects after recovery from COVID‐19 who had previously symptomatic and were followed outpatiently.MethodsThe study group composed of 50 subjects with a confirmed history of COVID‐19 and the control group composed of 50 healthy subjects without a history of COVID‐19 and vaccination. All the study participants underwent 2‐dimensional, pulsed‐ and tissue‐Doppler echocardiographic examinations and 24‐hour Holter monitoring for HRV analysis.ResultsTime domain parameters of SDNN, SDANN, SDNNi, RMSSD, pNN50, and HRV triangular index were all decreased in the study group when compared with the control group. Frequency domain parameters of TP, VLF, LF, HF, and HFnu were also decreased in the study group in comparison with the control group. LFnu was similar between groups. Nonlinear parameters of HRV including α1 and α2 decreased in the study group. By contrast, Lmax, Lmean, DET, REC, and Shannon entropy increased in the study population. Approximate and sample entropies also enhanced in the study group.ConclusionsThe present study showed that all three domain HRV significantly altered in patients after recovery from COVID‐19 indicating some degree of dysfunction in cardiac autonomic nervous system. HRV may be a useful tool for the detection of preclinical autonomic dysfunction in this group of patients.

Autonomic Modulation in Duchenne Muscular Dystrophy During a Computer Task: A Prospective Transversal Controlled Trial Assessment by Non-linear Techniques.

Introduction: Due to functional and autonomic difficulties faced by individuals with Duchenne Muscular Dystrophy (DMD), the use of assistive technology is critical to provide or facilitate functional abilities. The key objective was to investigate acute cardiac autonomic responses, by application of Heart Rate Variability (HRV), during computer tasks in subjects with DMD via techniques based on non-linear dynamics.Method: HRV was attained via a Polar RS800CX. Then, was evaluated by Chaotic Global Techniques (CGT). Forty-five male subjects were included in the DMD group and age-matched with 45 in the healthy Typical Development (TD) control group. They were assessed for 20 min at rest sitting, and then 5 min whilst performing the maze task on a computer.Results: Both TD and DMD subjects exhibited a significantly reduced HRV measured by chaotic global combinations when undertaking the computer maze paradigm tests. DMD subjects presented decreased HRV during rest and computer task than TD subjects.Conclusion: While there is an impaired HRV in subjects with DMD, there remains an adaptation of the ANS during the computer tasks. The identification of autonomic impairment is critical, considering that the computer tasks in the DMD community may elevate their level of social inclusion, participation and independence.

Alterations in Functional Connectivity Measured by Functional Magnetic Resonance Imaging and the Relationship With Heart Rate Variability in Subjects After Performing Orgasmic Meditation: An Exploratory Study.

Background: We measured changes in resting brain functional connectivity, with blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI), associated with a creative meditation practice that is augmented by clitoral stimulation and is designed to not only achieve a spiritual experience but to help individuals manage their most intimate personal relationships. Briefly, the meditative state is attained by both the male and female participants while the male stimulates the woman’s clitoris. The goal of this practice, called orgasmic meditation (OM), according to the practitioners is not sexual, but to use the focus on clitoral stimulation to facilitate a meditative state of connectedness and calm alertness between the two participants.Methods: fMRI was acquired on 20 pairs of subjects shortly following one of two states that were randomized in their order – during the OM practice or during a neutral condition. The practice is performed while the female is lying down on pillows with the clitoris exposed. During the practice, the male performs digital stimulation of the clitoris for 15 min. Resting BOLD image acquisition was performed at completion of the practice to assess changes in functional connectivity associated with the performance of the practice.Results: The results demonstrated significant changes (p < 0.05) in functional connectivity associated with the OM compared to the neutral condition. For the entire group there was altered connectivity following the OM practice involving the left superior temporal lobe, the frontal lobe, anterior cingulate, and insula. In female subjects, there was altered connectivity involving the cerebellum, thalamus, inferior frontal lobe posterior parietal lobe, angular gyrus, amygdala and middle temporal gyrus, and prefrontal cortex. In males, functional connectivity changes involved the supramarginal gyrus, cerebellum, and orbitofrontal gyrus, cerebellum, parahippocampus, inferior temporal gyrus, and anterior cingulate.Conclusion: Overall, these findings suggest a complex pattern of functional connectivity changes occurring in both members of the couple pair that result from this unique meditation practice. The changes represent a hybrid of functional connectivity findings with some similarities to meditation based practices and some with sexual stimulation and orgasm. This study has broader implications for understanding the dynamic relationship between sexuality and spirituality.

CONFIRMATION OF THE CLINICAL VALUE AND THE EFFECT OF SOUND BIOFEEDBACK ON THE AUTONOMIC NERVOUS SYSTEM THROUGH HEART RATE VARIABILITY ANALYSIS

The purpose of this study is to suggest sound biofeedback, which is a new technique of early stress relief effect by observing change in the heart rate variability (HRV). The sound biofeedback imitating heart rate of the comfortable and stress state is termed parasympathetic stimulation sound (PSS) and sympathetic stimulation sound (SSS), respectively. Twelve subjects were selected without previous history of cardiovascular diseases and mental illness, such as arrhythmia, myocardial infarction, depression and panic disorder. To confirm the changes in the low-frequency (LF), high-frequency (HF) and LF/HF values of HRV as stress evaluation indicators, the HRV of subjects was measured by photoplethysmogram. Signals were processed using the peak detect algorithm, and fast Fourier transform. Results were obtained using power specific densities. During the PSS stimulation, the LF/HF tended to decrease generally. On the other hand, during the SSS stimulation, LF/HF tended to increase. The LF/HF Mean change value ([Formula: see text]) using the PSS stimulation is similar to the effect of Transcutaneous Vagal Nerve Stimulation (tVNS). In addition, the quantitative effect of sound biofeedback was confirmed by judging changes in the parasympathetic and sympathetic nerves in the autonomic nervous system (ANS) through [Formula: see text]-score normalized data. These experimental results suggest that sound biofeedback has the same stimulation location and clinical applicability as tVNS. As a result, sound biofeedback may be used as a new method for stress reduction.

REGRESSION TO THE MEAN: METHODOLOGICAL ISSUES FOR EVALUATION OF HEART RATE VARIABILITY VARIABLES FOR STRESS ASSESSMENT

There is now a substantial body of evidence linking the baseline level of heart rate variability (HRV) with the magnitude of stress-induced reduction in respiratory sinus arrhythmia. However, it remains to be proved to what extent these interindividual differences in stress responses may be attributed to the statistical phenomenon of regression to the mean (RTM). We sought to test the hypothesis that the statistical artifact RTM explains pan of the baseline effect. Heart rate recording was carried out in 1156 volunteers. To obtain an estimate of the stress response. 148 persons were randomly selected. Participants were monitored on a rest day and just before an academic examination for state anxiety and HRV. Participants were divided into quartiles according to baseline HRV levels and were compared for response to academic stress. We observed a significant reduction in HRV in subjects with a high baseline HRV (&gt; 75th percentile), while a significant increase was found in the group with low baseline HRV. Regression analysis demonstrated that the value of baseline HRV correlated with the magnitude of stress reaction consistent with the RTM model. Baseline-adjusted ANCOVA does not reveal significant intergroup differences in the changes hi heart rate (HR) and HRV from rest to exam. RTM-adjusted estimates confirmed an exam effect for HR and HRV. The results of our study strongly support RTM as the source of variability of stress-related changes in HRV.

Investigating fractal dimension, heart rate variability, and memory during different image sequencing regimes in young adults.

The goal of this study is to investigate patterns that emerge in brain and heart signals in response to external stimulating image regimes. Data were collected from 84 subjects of ages 18-22. Subjects viewed a series of both neutrally and negatively arousing pictures during 2-min and 18-s-long segments repeated nine times. Both brain [electroencephalogram (EEG)] and heart signals [electrocardiogram (EKG)] were recorded for the duration of the study (ranging from 1.5 to 2.5 h) and analyzed using nonlinear techniques. Specifically, the fractal dimension was computed from the EEG to determine how this voltage trace is related to the image sequencing. Our results showed that subjects visually stimulated by a series of mixed images (a randomized set of neutrally or negatively arousing images) had a significantly higher fractal dimension compared to subjects visually triggered by pure images (an organized set of either all neutral or all negatively arousing images). In addition, our results showed that subjects who performed better on memory recall had a higher fractal dimension computed from the EEG. Analysis of EKG also showed greater heart rate variability in subjects who viewed a series of mixed images compared to subjects visually triggered by pure images. Overall, our results show that the healthy brain and heart are responsive to environmental stimuli that promote adaptability, flexibility, and agility.

P3753Does empagliflozin modulate the autonomic system among patients with type 2 diabetes and coronary artery disease? Insights from the Holter sub-study of the EMPA-Heart CardioLink-6 Randomised Trial

Abstract Introduction The mechanism behind how empagliflozin, a sodium-glucose co-transporter 2 (SGLT2) inhibitor, reduces all-cause and cardiovascular mortality among patients with type 2 diabetes (T2DM) and coronary artery disease (CAD) is unknown. Autonomic tone, as reflected by changes in heart rate variability (HRV), is an established prognosticator in patients with CAD and/or heart failure. Purpose To assess if empagliflozin treatment changes HRV in subjects with T2DM and CAD. Methods In the double-blind EMPA-Heart trial, 97 subjects with T2DM and CAD were randomised to empagliflozin 10 mg/day or placebo for 6 months and underwent 24-hour Holter monitoring at baseline and 6 months. Using automated algorithms, time and frequency HRV domain measures were obtained (standard deviation of NN intervals (SDNN); SD of the average NN intervals for each 5-minute segment (SDANN); root mean square of successive RR interval differences (rMSSD); % interval differences of successive NN intervals &gt;50 ms (pNN50); ratio of low to high frequency (LF/HF)). Changes of these HRV parameters were calculated over 6 months. Between-group differences in HRV parameters were compared using ANCOVA. Results Complete Holter data (baseline and 6-month) were available for 68% (n=66) of the cohort. The average heart rate (HR) at baseline/6 months was 69.5±9.8 bpm/72.8±8.1 bpm and 76±10.4 bpm/76.5±10.6 in the placebo group and empagliflozin group, respectively. Both groups had similar changes in average HR over 6 months. Key Holter data are summarised in the table. SDNN and SDANN were higher in the placebo vs. empagliflozin group at 6 months; no significant difference was noted for all other measures. Empagliflozin 10 mg/day (n=33) Placebo (n=33) Adjusted difference between Empagliflozin and Placebo (ANCOVA) Baseline, Mean (SD) 6-month, Mean (SD) Baseline, Mean (SD) 6-month, Mean (SD) Mean, (95% CI) P-value SDNN (ms) 100.49 (43.74) 98.05 (38.86) 109.35 (30.02) 125.08 (43.83) −18.55 (−34.28, −2.82) 0.022 SDANN (ms) 86.84 (39.34) 83.76 (35.53) 94.70 (28.52) 118.28 (77.41) −20.24 (−37.27, −3.21) 0.021 rMSSD (ms) 27.00 (11.84) 27.22 (13.48) 28.00 (11.58) 27.17 (9.38) −1.23 (−6.02, 3.55) 0.608 pNN50 (%) 7.81 (7.59) 8.32 (9.51) 8.26 (7.8) 6.93 (5.35) 0.51 (−2.61, 3.62) 0.746 LF/HF ratio 1.63 (0.52) 1.65 (0.51) 1.53 (0.43) 1.83 (0.82) −0.08 (−0.38, 0.22) 0.602 Conclusions Among subjects with T2DM and CAD, changes in HRV over 6 months were similar in the empagliflozin and placebo arms suggesting that the mortality benefit conferred by empagliflozin is not associated with positive modulation of autonomic tone. Acknowledgement/Funding This trial was supported by an unrestricted investigator-initiated study grant from Boehringer Ingelheim.

Association between diabetic peripheral neuropathy and heart rate variability in subjects with type 2 diabetes

AimThis study evaluated the association of Heart rate variability (HRV) measurements with diabetic peripheral neuropathy (DPN) in patients with type 2 diabetes. MethodsThis study included 102 Korean subjects with type 2 diabetes. The Michigan neuropathy screening instrument (MNSI) questionnaire score, the MNSI examination score (MNSIES) and the total symptom score were examined for DPN evaluation. Noninvasive HRV measurements were performed using photoelectric plethysmography. Patients with a MNSIES > 2 were considered to have DPN. ResultsThe MNSIES showed significant negative associations with the high frequency (HF) (r = −0.212, p = 0.033) and low frequency (LF) (r = −0.286, p = 0.004) powers. Multiple linear regression analysis revealed that only HF power maintained a significant negative association with the MNSIES (β = −0.184; 95% CI −0.365 to −0.003; p = 0.047), after controlling for significant related confounders, with HRV parameters in male patients with type 2 diabetes. The HF (p = 0.010) and LF (p = 0.025) powers differed significantly between male patients without and those with DPN according to the MNSIES. ConclusionsThis study revealed a negative association of DPN, as assessed by the MNSIES, with HF power in male patients with type 2 diabetes. DPN defined by foot examination was predictive of cardiac autonomic neuropathy.

Age features of heart rate variability in obesity

Obesity is considered as one of the most significant health problems around the world, whose prevalence has increased dramatically in recent years.The aim of the study is the determination of the age-specific features of the daily heart rate variability in subjects with obesity.Materials and Methods: 118 persons with obesity and overweight in the age of 19-66 years old were examined. The control group included 25 practically healthy persons. А general clinical examination with obligatory measurements of the circumference of the waist and hips, weight and height, daily monitoring of the ECG were conducted to participants of the study.As a result, the presence of dysfunction of the autonomic nervous system during the day was established in obese patients in all age groups. Young subjects had decrease activity of parasympathetic nervous system and increase of activity of sympathetic nervous system in comparison with subjects without obesity.Conclusions. Dysfunction of the autonomic nervous system in obesity included the increasing activity of the sympathetic nervous system and decreasing activity of the parasympathetic nervous system in day and night time. There was a progressive decrease in the activity of the parasympathetic nervous system with increasing the age of subjects

Intermittent 96-Hour Auricular Electroacupuncture for Hot Flashes in Patients with Prostate Cancer: A Pilot Study.

Objective: The hot flash is a common vasomotor disorder that causes distress in menopausal women and that can be debilitating in men with prostate cancer who are treated with androgen deprivation therapy (ADT). The utility of auricular electroacupuncture (AEA) was tested exclusively for a small cohort of men with ADT-induced vasomotor symptoms while the men underwent a course of curative radiotherapy. Materials and Methods: Prior to and during radiotherapy treatment, men with vasomotor symptoms were given repeated questionnaires regarding severity and frequency of hot flashes, quality of life (QoL), and sleep over a 6-week span of an AEA protocol. Each subject's heart rate variability (HRV) was obtained repeatedly every week in an ambulatory setting with a BlueCardio device (BlueCardio, Miami, FL). The AEA intervention was given with a Neurova device (Nunka Corporation, CM Wellness Clinic, Pompano Beach, FL) that used three needles at Master points Sympathetic, Shen Men, and Point Zero, which were located precisely with a bipolar point finder. Intermittent microcurrent stimulation was given every other week for 96 hours, using a cyclic programmed output of 2 hours on and 2 hours off. Results: Of 10 men completing the 6-week protocol, all responded with significantly lower frequency, duration, and severity of vasomotor symptoms; QoL and sleep scores improved significantly. The HRV analysis showed significantly lower low-frequency/high-frequency power ratios in each individual, compared to baseline, that were consistent with the subjective responses. Conclusions: Vasomotor disturbance, caused by gender hormone withdrawal-either naturally or in patients treated with ADT, as in this study-is a well-defined neurophysiologic condition. This disorder is a constellation of findings that reflect autonomic disturbances of excessive sympathetic and reduced parasympathetic activity. AEA intervention with the Neurova device is simple to administer, is well-tolerated, and appears to be effective for restoring autonomic balance. Further evaluation of AEA for vasomotor disturbances could provide more insight into the mechanisms of AEA neuromodulation and potentially lead to approaches for treating not only these symptoms but also other neurologic conditions with components of autonomic disturbances.

Gender Differences on Heart Rate Variability of Subjects Exposed to Regular Resistance Training Routine

Heart rate variability (HRV) using frequency‐domain method is a tool for evaluating autonomic balance. In this cross‐sectional study, we investigated the low frequency (LF), high frequency (HF) and the LF/HF ratio components of the spectral analysis in men (n= 22) and women (n = 27) exposed to resistance training using the nerve express system analyzed by Student's t test. The study was approved by Ethics Committee of the Center for Health Sciences of the Federal University of Paraiba and was in accordance with the Helsinki Declaration of 1975, as revised in 2008. Our hypothesis was that there is a gender difference on HRV when subjects were exposed to resistance training. In men, the LF component was increased during supine (1171 ± 192 vs. 545 ± 74 ms2, P = 0.0067) and upright position after the orthostatic test (1824 ± 260 vs. 738 ± 133 v, P = 0.0011). In addition, LF/HF ratio, an index for sympathovagal balance, was increased in male subjects compared to females. These data suggest a possible gender difference on HRV of individuals exposed to resistance training.Support or Funding InformationSupported by Capes and CNPq

コミュニケーションロボットのための自律神経活動の推定

The purpose of this study is to enable a communication robot to estimate emotion state of a person based on autonomic nervous activity for human-robot ‘emotional’ interaction. In this paper, a microwave Doppler sensor is used as a non-contact technique to measure heart rate variability related to autonomic nervous activity. The experiment was conducted to confirm whether our proposed method can precisely estimate heart rate variability of subjects during watching different genre of videos or speaking. The results showed that the proposed method can estimate variability of autonomic nervous activity based on the analysis of heartbeat interval (R-R interval) and has a potential to be applicable in human-robot interaction.

Comparing the Effects of Rest and Massage on Return to Homeostasis Following Submaximal Aerobic Exercise: a Case Study

Postexercise massage can be used to help promote recovery from exercise on the cellular level, as well as systemically by increasing parasympathetic activity. No studies to date have been done to assess the effects of massage on postexercise metabolic changes, including excess postexercise oxygen consumption (EPOC). The purpose of this study was to compare the effects of massage recovery and resting recovery on a subject's heart rate variability and selected metabolic effects following a submaximal treadmill exercise session. One healthy 24-year-old female subject performed 30 minutes of submaximal treadmill exercise prior to resting or massage recovery sessions. Metabolic data were collected throughout the exercise sessions and at three 10 minute intervals postexercise. Heart rate variability was evaluated for 10 minutes after each of two 30-minute recovery sessions, either resting or massage. Heart rate returned to below resting levels (73 bpm) with 30 and 60 minutes of massage recovery (72 bpm and 63 bpm, respectively) compared to 30 and 60 minutes of resting recovery (77 bpm and 74 bpm, respectively). Heart rate variability data showed a more immediate shift to the parasympathetic state following 30 minutes of massage (1.152 LF/HF ratio) versus the 30-minute resting recovery (6.91 LF/HF ratio). It took 60 minutes of resting recovery to reach similar heart rate variability levels (1.216 LF/HF) found after 30 minutes of massage. Ventilations after 30 minutes of massage recovery averaged 7.1 bpm compared to 17.9 bpm after 30 minutes of resting recovery. No differences in EPOC were observed through either the resting or massage recovery based on the metabolic data collected. Massage was used to help the subject shift into parasympathetic activity more quickly than rest alone following a submaximal exercise session.

Dynamics of EEG α activity and heart rate variability in subjects performing cognitive tests

Changes in the power and coherence of α-activity and heart rate variability (HRV) were studied in students with different performance levels in logical tasks. In those students who reached high scores in the cognitive tests, we observed higher lability of α-activity and HRV; the values and their ratios varied among the stages of intellectual activity. In these subjects, a decrease in the spectral power of α-band was more pronounced than in other groups. We also observed changes in the interhemispheric coherence and in the structure of coherent interactions in the α-range at different stages of task performance. In contrast, the number and structure of coherent interactions in individuals who showed lower results did not significantly vary at different stages of task performance. As compared with this group, the students with higher test results showed a more pronounced decrease in the total spectral power (TP) and an increase in the low frequency/high frequency (LF/HF) ratio which returned to the initial level after the end of the tests. In students with better results in these cognitive tests, the dynamics of RRNN, TP, HF, and LF/H F during task performance correlated with the dynamics of interhemispherical α-band coherence.

Enhancing Heart-Beat-Based Security for mHealth Applications.

In heart-beat-based security, a security key is derived from the time difference between consecutive heart beats (the inter-pulse interval, IPI), which may, subsequently, be used to enable secure communication. While heart-beat-based security holds promise in mobile health (mHealth) applications, there currently exists no work that provides a detailed characterization of the delivered security in a real system. In this paper, we evaluate the strength of IPI-based security keys in the context of entity authentication. We investigate several aspects that should be considered in practice, including subjects with reduced heart-rate variability (HRV), different sensor-sampling frequencies, intersensor variability (i.e., how accurate each entity may measure heart beats) as well as average and worst-case-authentication time. Contrary to the current state of the art, our evaluation demonstrates that authentication using multiple, less-entropic keys may actually increase the key strength by reducing the effects of intersensor variability. Moreover, we find that the maximal key strength of a 60-bit key varies between 29.2 bits and only 5.7 bits, depending on the subject's HRV. To improve security, we introduce the inter-multi-pulse interval (ImPI), a novel method of extracting entropy from the heart by considering the time difference between nonconsecutive heart beats. Given the same authentication time, using the ImPI for key generation increases key strength by up to 3.4 × (+19.2 bits) for subjects with limited HRV, at the cost of an extended key-generation time of 4.8 × (+45 s).

Effects of Personal Exposure to Ambient Fine Particulate Matter on Acute Change in Nocturnal Heart Rate Variability in Subjects Without Overt Heart Disease

The immediate effect within minutes to hours of personal exposure to ambient fine particulate matter (PM2.5) on cardiac autonomic function is limited, particularly at night. Our study aimed to assess the lagged association between personal exposure to PM2.5 and nocturnal heart rate variability. Repeated measures panel study among 21 community adults recruited from a local health clinic during the period of March 1, 2004, to August 31, 2004, in Boston, Massachusetts, in the United States. Ambulatory electrocardiogram and continuous monitoring of personal exposure to PM2.5 and were measured for up to 2 consecutive days. We calculated 5-minute time-specific average PM2.5 exposure for each participant. Mixed-effects models were fit for 5-minute SD of normal-to-normal intervals (SDNN) and 5-minute heart rate in relation to 5-minute PM2.5 exposure lagged in 5-minute intervals up to 4 hours. We found an 8.4% decrease in nocturnal SDNN (95% confidence interval [CI] -11.3% to -5.5%) and a 1.9% increase in nighttime heart rate (95% CI 1.1% to 2.7%) for an interquartile range increase in PM2.5 (13.6 μg/m(3)), after adjusting for confounders. Significant decreases in nocturnal SDNN associated with PM2.5 exposure occurred within 2.5 hours. The largest decrease in nocturnal SDNN of -12.8% (95% CI -16.4 to -9.1%) that was associated with PM2.5 exposure was found with a lag of 25 minutes. Rapid changes in nocturnal heart rate variability associated with personal PM2.5 exposure occurred within the previous 2.5 hours, with the largest effects at 25 minutes, suggesting immediate cardiac autonomic effects of fine particulate exposure.