Significant Changes In Heart Rate Variability Research Articles

Early heart rate variability changes during acute fetal inflammatory response syndrome: An experimental study in a fetal sheep model.

Fetal infection during labor with fetal inflammatory response syndrome (FIRS) is associated with neurodevelopmental disabilities, cerebral palsy, neonatal sepsis, and mortality. Current methods to diagnose FIRS are inadequate. Thus, the study aim was to explore whether fetal heart rate variability (HRV) analysis can be used to detect FIRS. In chronically instrumented near-term fetal sheep, lipopolysaccharide (LPS) was injected intravenously to model FIRS. A control group received saline solution injection. Hemodynamic, blood gas analysis, interleukin-6 (IL-6), and 14 HRV indices were recorded for 6 h. In both groups, comparisons were made between the stability phase and the 6 h following injection (H1-H6, respectively) and between LPS and control groups. Fifteen lambs were instrumented. In the LPS group (n = 8), IL-6 increased significantly after LPS injection (p < 0.001), confirming the FIRS model. Fetal heart rate increased significantly after H5 (p < 0.01). In our FIRS model without shock or cardiovascular decompensation, five HRV measures changed significantly after H2 until H4 in comparison to baseline. Moreover, significant differences between LPS and control groups were observed in HRV measures between H2 and H4. These changes appear to be mediated by an increase of global variability and a loss of signal complexity. As significant HRV changes were detected before FHR increase, these indices may be valuable for early detection of acute FIRS.

Heart rate variability and cardiovascular risk factors in patients with rheumatoid arthritis: A longitudinal study.

It is established that the risk of cardiovascular disease (CVD) is increased in patients with Rheumatoid Arthritis (RA). Heart rate variability (HRV) is a method for evaluating the activity in the cardiac autonomic nervous system. Our aim was to assess the longitudinal development of HRV in patients with RA and compare with healthy controls. Furthermore, we wanted to investigate associations between HRV, inflammatory disease activity and cardiovascular complications in patients with RA over time. HRV was assessed with frequency-domain analysis at baseline and after five years in 50 patients with early RA, all being younger than 60years. HRV indices were age-adjusted based on the estimated age-dependency in 100 age and sex matched healthy controls. Additionally, clinical data including serological markers, disease activity, and blood pressure were collected from the patients. Eleven years after inclusion CVD was assessed. At baseline, patients with RA presented with lower HRV compared to controls during deep breathing (6 breaths/min), paced normal breathing (12 breaths/min) and after passive tilt to the upright position. No significant change in HRV was observed at the five-year follow-up. A significant negative correlation was found between HRV parameters and systolic blood pressure (SBP) at baseline. A significant positive correlation was found between heart rate and inflammatory markers at baseline but not after five years. Nine patients had developed CVD after 11years, but no significant association was found with baseline HRV data. This study showed that patients with RA have autonomic imbalance both at an early stage of the disease and after five years, despite anti-rheumatic medication, but no correlation between HRV and inflammation markers were observed. Reduced HRV was also significantly negatively correlated with increased SBP. Hypertension is a common finding in patients with RA. Thus, significant decline of HRV could be a useful early marker for development of hypertension in patients with RA.

ALIVE Biofeedback HRV training for Treating Insomnia: A Pilot Randomized Controlled Study.

Background: Insomnia is a common sleep disorder that affects a large portion of the population. While several treatments are available, such as medication and cognitive-behavioral therapy, some individuals may not respond well to these treatments. Biofeedback, a technique that provides individuals with real-time feedback on their physiological responses, has shown promise in treating insomnia. This study aimed to investigate the effectiveness of ALIVE biofeedback HRV training in treating insomnia. Methodology: This pilot study utilized a randomized controlled trial design to investigate the efficacy of ALIVE biofeedback intervention in individuals diagnosed with insomnia. A total of 60 participants with insomnia were randomly assigned to either the ALIVE biofeedback or control group. The ALIVE biofeedback group received a six week intervention involving relaxation techniques, deep breathing exercises, and mindfulness meditation using the ALIVE Pioneer system for heart rate variability (HRV) biofeedback training. The control group received standard care for insomnia. Outcome measures included HRV parameters, blood pressure, the Pittsburgh Sleep Quality Index Japanese version (PSQI J), and the Insomnia Severity Index (ISI). Results: The ALIVE biofeedback group showed significant improvements in heart rate variability (HRV) parameters, including increased SDNN and RMSSD and high-frequency power (HF) after the 6-week intervention. The control group did not display significant changes in HRV. Additionally, the ALIVE biofeedback group significantly decreased diastolic blood pressure. Regarding sleep outcomes, the ALIVE biofeedback group reported increased sleep duration and decreased sleep disturbances, as indicated by the PSQI-J scores. Furthermore, participants in the ALIVE biofeedback group significantly improved their ISI scores. These findings suggest that the ALIVE biofeedback intervention can potentially improve HRV, blood pressure, sleep quality, and insomnia severity in individuals with insomnia. Conclusion: It is concluded from the study results that the ALIVE biofeedback training is a non-invasive and effective treatment for insomnia.

SPECIAL ISSUE: Exploring the Effects of Shared Heart-Focused Intention in Music Performance on Musicians and Audience Members

This exploratory study sought to determine if a shared group intention by members of a string quartet for two pieces of music would have an effect on themselves and audience members. An experimental design was implemented consisting of two interventions. The first intervention introduced a series of exercises focused on posture and biomechanical movements. The second intervention introduced HeartMath’s Quick Coherence and Heart Lock-In techniques. The Pachelbel Canon in D and Mozart Divertimenti in F K138 were chosen as the works to perform. For data collection, all participants (N = 12) were fitted with ambulatory Bodyguard heart rate variability (HRV) recorders. Qualitative data were collected with questionnaires, and videos recorded comments. All three sessions were video recorded. Repeated-measures analysis of variance was used to test within-subjects effects in baseline HRV measurements among three sessions. Audience participants (n = 8) and musician participants (n = 4) were analyzed as separate groups. Quantitative results showed a significant change in HRV among the musicians from baseline after the Heart Lock-In breathing technique was introduced. Qualitative results showed improved mental focus and feelings of connectivity among the musicians. Audience HRV data had a high level of artifact, and the results showed no significance. After the final performance, qualitative comments focused on the performances being more engaging and the musicians being more connected with each other.

PO-01-235 EPICARDIAL PULSED-FIELD ABLATION OF THE CARDIAC GANGLIONATED PLEXI: IMPACTS ON THE AUTONOMIC NERVOUS SYSTEM

The autonomic nervous system (ANS) has been shown to play a role in the initiation and maintenance of atrial fibrillation (AF). While incidental ablation of the Ganglionated Plexi (GP) during AF ablation changes the ANS in a manner which correlates with procedural success, targeted ablation of GP has met with mixed results. In pre-clinical models, pulsed field (PF) energy delivered epicardially has demonstrated the capability to ablate GP without damage to surrounding myocardium. This is a first in human analysis to investigate the feasibility and safety of epicardial PF ablation (PFA) during cardiac surgery. In a single arm, prospective analysis, patients with or without a history of AF underwent epicardial PFA (OCED, AtriAN[RV1] Inc, Dublin) during planned coronary artery bypass grafting (CABG; see Figure). ANS tone was assessed via intraoperative pacing maneuvers to assess atrial effective refractoriness (AERP) and with Holter-assessment of heart rate variability (HRV) at baseline and 3 months post procedure. Most enrolled patients (23 of 24) received the full ablation protocol with no device-related adverse effects. Pacing demonstrated a 20.7±19.9% extension in AERP (P<0.001). Holter monitoring demonstrated an increase in mean heart rate (74.0±8.7 vs 80.6±12.3 BPM, P=0.01). While there was a trend towards a decrease in SDNN (188±31 vs 104±40, P=0.20), there were no significant changes in HRV. Post-operative AF (POAF) was noted in 7 (29%) of patients. This study demonstrates the safety and feasibility of epicardial PFA of the cardiac GP aimed at modulating the ANS during CABG. While changes in AERP suggest acute efficacy, assessment of the long-term effects and impact on the incidence of POAF is limited by the small sample size and single-arm nature of this analysis. Larger, randomized studies are needed to determine the long-term impact of epicardial PFA and its ability to mitigate POAF.

Electronic cigarettes exposures modulate Heart Rate and Heart Rate Variability

Background: Despite a lack of empirical data, an unprecedented rise in electronic cigarettes (ECs) has been widely perceived as safe. Multiple studies support a causal link between tobacco cigarette (TC) use and cardiovascular (CV) diseases; however, there is a lack of data with EC use. We have previously shown that chronic and acute EC use decreases heart rate variability (HRV) in humans, likely via increased sympathetic nervous system activation. Objective: We aimed to evaluate HRV effects induced by brief EC exposures utilizing an in-vivo model for freely moving C57BL/6 mice. Methods and Results: Telemetry devices were implanted in the abdomen of six 10-week-old C57BL/6 male mice to monitor electrocardiographic activity continuously. Mice underwent an exposure protocol designed to reflect human vaping topography with two EC exposures, each lasting 15-minutes (4-sec puff/ 26-sec Air) followed by 45-min post-exposure periods. Air (primary control) and PBS (secondary control) were also included, each with their own post-exposure events. During EC exposures, we observed bradycardic effects in heart rate (HR) with the standard deviation of NN intervals (SDNN), root mean square of successive differences (RMSSD), and the proportion of adjacent normalized RR intervals that differed by more than 6 ms (pNN 6 ) significantly (p&lt; 0.05) altered as compared to Air exposures. After EC exposures, SDNN, RMSSD and pNN 6 parameters significantly decreased compared to Air. No significant differences between Air and PBS were observed in these parameters. Frequency domain parameters also indicated significant changes in HRV; the low frequency (LF) and high frequency (HF) bands showed marked increases during and after the EC exposures, while the log (LF/HF) ratio remained relatively unchanged, suggesting a possible coactivation of both parasympathetic and sympathetic branches of the autonomic nervous system. Conclusion: Short-term EC exposures lower heart rate and altered HRV in mice in an acute manner, suggesting that ECs may not be safe as previously assumed. This work was funded by the Tobacco-Related Disease Research Program (TRDRP) which included the High Impact Pilot Research Award [28IP-0036], the Cornelius Hopper Diversity Award Supplement and the Student Research Award Supplement, the UCLA Center for Occupational and Environmental Health (COEH) Student Project Award, and in part by the National Institute of Environmental Health Sciences (NIEHS) via the Student-to-Scientist Bridge program at California State University, Northridge [5R25ES025507]. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Physiological and Psychological Stress of Microwave Radiation-Induced Cardiac Injury in Rats

Electromagnetic waves are widely used in both military and civilian fields, which could cause long-term and high-power exposure to certain populations and may pose a health hazard. The aim of this study was to simulate the long-term and high-power working environment of workers using special electromagnetic radiation occupations to clarify the radiation-induced stress response and cardiac damage and thus gain insights into the mechanisms of injuries caused by electromagnetic radiation. In this study, the combination of microwave and stress was an innovative point, aiming to broaden the research direction with regard to the effect and mechanism of cardiac injury caused by radiation. The myocardial structure was observed by optical and transmission electron microscope, mitochondrial function was detected by flow cytometry, oxidative-stress markers were detected by microplate reader, serum stress hormone was detected by radioimmunoassay, and heart rate variability (HRV) was analyzed by multichannel-physiological recorder. The rats were weighed and subjected to an open field experiment. Western blot (WB) and immunofluorescence (IF) were used to detect the expressions and distributions of JNK (c-Jun N-terminal kinase), p-JNK (phosphorylated c-Jun N-terminal kinase), HSF1 (heat shock factor), and NFATc4 (nuclear factor of activated T-cell 4). This study found that radiation could lead to the disorganization, fragmentation, and dissolution of myocardial fibers, severe mitochondrial cavitation, mitochondrial dysfunction, oxidative-stress injury in myocardium, increase to stress hormone in serum, significant changes in HRV, and a slow gain in weight. The open field experiment indicated that the rats experienced anxiety and depression and had decreased exercise capacity after radiation. The expressions of JNK, p-JNK, HSF1, and NFATc4 in myocardial tissue were all increased. The above results suggested that 30 mW/cm2 of S-band microwave radiation for 35 min could cause both physiological and psychological stress damage in rats; the damage was related to the activation of the JNK pathway, which provided new ideas for research on protection from radiation.

Effects of High-Intensity Interval Training and Continuous Training on Exercise Capacity, Heart Rate Variability and Isolated Hearts in Diabetic Rats.

High-intensity interval training (HIIT) has been suggested as an alternative for continuous training (CT) in people with diabetes mellitus (DM) due to its short duration and potential to improve adherence to exercise. However, data on its impact on heart rate variability (HRV) are scarce. To assess and compare the effects of HIIT and CT on exercise capacity, HRV and isolated hearts in diabetic rats. DM (intravenous streptozotocin, 45 mg.kg -1 ) and control (C) animals performed 20 sessions (5 days/week, 50 min, for 4 weeks) of CT on a treadmill (70% of maximal exercise capacity) or HIIT (cycles of 1:1min at 50% and 90% of maximal exercise capacity). HRV was assessed by continuous electrocardiogram, and cardiac function assessed in isolated perfused hearts. For data analysis, we used the framework of the multivariate covariance generalized linear model or one-way ANOVA followed by Tukey's test, considering p<0.05 as significant. Higher exercise capacity (m/min) was achieved in HIIT (DM-HIIT: 36.5 [IQR 30.0-41.3]; C-HIIT: 41.5 [37.8-44.5], both n=10) compared to CT (DM-CT: 29.0 [23.8-33.0]; C-CT: 32.0 [29.5-37.0], both n=10) (p<0.001). Heart rate (bpm) was lower in DM compared to controls (p<0.001) both in vivo (DM-HIIT:348±51, C-HIIT:441±66, DM-CT:361±70, C-CT:437±38) and in isolated hearts. There were no differences in HRV between the groups. Maximum and minimal dP/dt were reduced in DM, except +dP/dt in DM-HIIT vs. C-HIIT (mean difference: 595.5±250.3, p=0.190). Short-term HIIT promotes greater improvement in exercise performance compared to CT, including in DM, without causing significant changes in HRV.

Acute Effects of Nicotine on Physiological Responses and Sport Performance in Healthy Baseball Players.

There is interest in whether nicotine could enhance attention in sporting performance, but evidence on the acute effect of nicotine on physical response and sports performance in baseball players remains scant. This was an observational study to examine whether nicotine gum chewed before exercise could provide acute effects on physiological responses and sport performance. Accordingly, heart rate variability (HRV), saliva cotinine concentration and α-amylase activity, cognitive function, muscle strength, and baseball-hitting performance were measured. Thirteen healthy male non-smoker baseball players were recruited. Conducting two sequences with 7-day intervals, they chewed nicotine gum (nicotine group) or flavor-matched placebo gum (placebo group) for 30 min. HRV and saliva analyses were conducted before gum consumption (S1), after gum consumption (S2), and after test completion (S3). Cognitive, muscle strength, and baseball-hitting performance tests were performed after nicotine or placebo gum chewing. The outcomes of all assessed variables were compared within and between the groups. Significant changes in HRV, α-amylase, testosterone, and cortisol were observed in the nicotine group at S2 and S3 (p < 0.05). Compared with the placebo group, the nicotine group exhibited enhanced motor reaction times, grooved pegboard test (GPT) results on cognitive function, and baseball-hitting performance, and small effect sizes were noted (d = 0.47, 0.46 and 0.41, respectively). Nicotine could induce changes in endocrine and sympathetic nerve activity and enhance cognitive function and baseball-hitting performance. However, no increase in muscle strength was observed after nicotine intake.

Heart rate variability in persons of Tajik nationality during adaptation

Relevance . Maintaining the health of migrants while adapting to the new climatic and geographical conditions of residence is an urgent task. The impact of non-specific factors on the body of migrants in new climatogeographic conditions leads to the strain of regulatory and adaptive mechanisms, and in extreme cases to their failure. Objective - to determine the features of heart rate variability in young Tajiks, depending on the type of temperament living in Krasnoyarsk for more than a year. Materials and Methods: A study of heart rate variability in 63 Tajiks aged 18-40 years with different types of temperament, living in Krasnoyarsk for more than a year, was conducted. The types of temperament were determined by indices in accordance with the method of identifying VP-types of temperament according to E.Yu. Petrosyan, Yu. I. Savchenkov. The following indicators of heart rate variability (HRV) were evaluated: heart rate, the power of the high-frequency, low-frequency and very low-frequency spectrum (BV, MV-2, MV-1) of the HRV component, the voltage index of regulatory systems (IN), the centralization index (CI) and the activity index of regulatory systems. To assess the statistical significance of the differences between the samples, the Students criteria were used. Results and Discussion. It was revealed that migrants with an intense type of temperament after moving to a new place of residence increased the indicators of heart rate, BV and IN. At the same time, in the studied groups with a calm and adequate type of temperament, the power of BV was significantly reduced, with an increase in heart rate and CI. The conclusion is made about the influence of typological features of temperament on HRV indicators, when adapting to new climatogeographic living conditions. Individuals with an adequate type of temperament demonstrate the normal functioning of the adaptive capabilities of the body. In individuals with the calm type, an increase in the tension of the regulatory mechanisms was revealed. Conclusion . Significant changes in HRV are demonstrated by migrants with an intense type of temperament, in particular, they are characterized by a high voltage of regulatory mechanisms.

Effect of Mental Activity on Heart Rate, Heart Rate Variability and Respiratory Rate in Healthy Volunteers

Introduction: The link between mental stress and cardiac autonomic regulation plays a significant role in the patho physiological process of cardio neural feedback loop. This study assessed the effect of mental arithmetic and silent reading on heart rate variability, heart rate and respiratory rate in young healthy volunteers.&#x0D; Materials and Methods: R-R intervals were recorded for five minutes in ten healthy volunteers aged 22-24 years of either sex while resting, doing mental arithmetic, and silent reading in a sitting position. Time and frequency domain approaches were used to measure heart rate variability (HRV). In them, heart rate and respiratory rate were also calculated. Using the paired ‘t' test, mean differences in values were evaluated between resting and mental arithmetic; resting and quiet reading conditions.&#x0D; Results: Heart rate and respiratory rate were significantly higher during mental arithmetic (p = 0.012, p&lt;0.0001 respectively) and silent reading compared to resting state (p=0.005, p=0.0002 respectively). There was no significant change in HRV during mental arithmetic and silent reading compared to resting state.&#x0D; Conclusion: Mental arithmetic and silent reading primarily evoke a rise in respiratory rate and heart rate.

Use of Physiological Data From a Wearable Device to Identify SARS-CoV-2 Infection and Symptoms and Predict COVID-19 Diagnosis: Observational Study.

BackgroundChanges in autonomic nervous system function, characterized by heart rate variability (HRV), have been associated with infection and observed prior to its clinical identification.ObjectiveWe performed an evaluation of HRV collected by a wearable device to identify and predict COVID-19 and its related symptoms.MethodsHealth care workers in the Mount Sinai Health System were prospectively followed in an ongoing observational study using the custom Warrior Watch Study app, which was downloaded to their smartphones. Participants wore an Apple Watch for the duration of the study, measuring HRV throughout the follow-up period. Surveys assessing infection and symptom-related questions were obtained daily.ResultsUsing a mixed-effect cosinor model, the mean amplitude of the circadian pattern of the standard deviation of the interbeat interval of normal sinus beats (SDNN), an HRV metric, differed between subjects with and without COVID-19 (P=.006). The mean amplitude of this circadian pattern differed between individuals during the 7 days before and the 7 days after a COVID-19 diagnosis compared to this metric during uninfected time periods (P=.01). Significant changes in the mean and amplitude of the circadian pattern of the SDNN was observed between the first day of reporting a COVID-19–related symptom compared to all other symptom-free days (P=.01).ConclusionsLongitudinally collected HRV metrics from a commonly worn commercial wearable device (Apple Watch) can predict the diagnosis of COVID-19 and identify COVID-19–related symptoms. Prior to the diagnosis of COVID-19 by nasal swab polymerase chain reaction testing, significant changes in HRV were observed, demonstrating the predictive ability of this metric to identify COVID-19 infection.

A Virtual Reality Game to Assess OCD Symptoms.

Background: Symptoms of obsessive-compulsive disorder (OCD) are often underreported by patients and mainly triggered in the patients private domain, making it harder for clinicians to recognize OCD. Virtual reality (VR) can be used to assess OCD symptoms in the clinician's office. We developed a VR game in order to provoke subjective and physiological OCD symptoms. We hypothesize that (1) the VR game provokes more OCD symptoms in patients compared to healthy controls, (2) performing virtual compulsions leads to a reduction in emotional responses in OCD patients and that (3) the severity of VR game provoked symptoms correlates with severity of OCD symptoms.Methods: Participants played the VR game on a laptop while physiological measures were recorded simultaneously. We measured emotional responses, virtual compulsions and physiological arousal in response to our VR game in 26 OCD patients and 26 healthy controls. We determined correlations between emotional responses, virtual compulsions and OCD severity.Results: We found higher levels of VR-provoked anxiety (U = 179.5, p = 0.004) and virtual compulsions in OCD patients compared to healthy controls (p = 0.001). There was a significant reduction in emotional responses after performing virtual compulsions in the OCD patients. The emotional responses and virtual compulsions did not correlate significantly with Y-BOCS scores. A baseline difference between patients and healthy controls was found in heart rate variability (HRV), but no significant change in HRV, heartrate and skin conductance was found during the VR gameConclusions: Our study clearly shows our OCD VR game is capable of provoking more anxiety and virtual compulsions in patients with OCD compared to healthy controls. Providing a direct patient-rated measurement in the clinicians room, the VR game could help in assessing core OCD symptoms and recognizing OCD.Clinical Trial Registry Number: Netherlands Trial Register NTR5935.

Longitudinal Autonomic Nervous System Measures Correlate With Stress and Ulcerative Colitis Disease Activity and Predict Flare.

Differences in autonomic nervous system function, measured by heart rate variability (HRV), have been observed between patients with inflammatory bowel disease and healthy control patients and have been associated in cross-sectional studies with systemic inflammation. High HRV has been associated with low stress. Patients with ulcerative colitis (UC) were followed for 9 months. Their HRV was measured every 4 weeks using the VitalPatch, and blood was collected at baseline and every 12 weeks assessing cortisol, adrenocorticotropin hormone, interleukin-1β, interleukin-6, tumor necrosis factor-α, and C-reactive protein (CRP). Stool was collected at enrollment and every 6 weeks for fecal calprotectin. Surveys assessing symptoms, stress, resilience, quality of life, anxiety, and depression were longitudinally collected. Longitudinally evaluated perceived stress was significantly associated with systemic inflammation (CRP, P = 0.03) and UC symptoms (P = 0.02). There was a significant association between HRV and stress (low-frequency to high-frequency power [LFHF], P = 0.04; root mean square of successive differences [RMSSD], P = 0.04). The HRV was associated with UC symptoms (LFHF, P = 0.03), CRP (high frequency, P < 0.001; low frequency, P < 0.001; RMSSD, P < 0.001), and fecal calprotectin (high frequency, P < 0.001; low frequency, P < 0.001; RMSSD, P < 0.001; LFHF, P < 0.001). Significant changes in HRV indices from baseline developed before the identification of a symptomatic or inflammatory flare (P < 0.001). Longitudinally evaluated HRV was associated with UC symptoms, inflammation, and perceived and physiological measures of stress. Significant changes in HRV were observed before the development of symptomatic or inflammatory flare.

Panel study using novel sensing devices to assess associations of PM2.5 with heart rate variability and exposure sources.

This work applied a newly developed low-cost sensing (LCS) device (AS-LUNG-P) and a certified medical LCS device (Rooti RX) to assessing PM2.5 impacts on heart rate variability (HRV) and determining important exposure sources, with less inconvenience to subjects. Observations using AS-LUNG-P were corrected by side-by-side comparison with GRIMM instruments. Thirty-six nonsmoking healthy subjects aged 20-65 years were wearing AS-LUNG-P and Rooti RX for 2-4 days in both Summer and Winter in Taiwan. PM2.5 exposures were 12.6 ± 8.9 µg/m3. After adjusting for confounding factors using the general additive mixed model, the standard deviations of all normal to normal intervals reduced by 3.68% (95% confidence level (CI) = 3.06-4.29%) and the ratios of low-frequency power to high-frequency power increased by 3.86% (CI = 2.74-4.99%) for an IQR of 10.7 µg/m3 PM2.5, with impacts lasting for 4.5-5 h. The top three exposure sources were environmental tobacco smoke, incense burning, and cooking, contributing PM2.5 increase of 8.53, 5.85, and 3.52 µg/m3, respectively, during 30-min intervals. This is a pioneer in demonstrating application of novel LCS devices to assessing close-to-reality PM2.5 exposure and exposure-health relationships. Significant HRV changes were observed in healthy adults even at low PM2.5 levels.

AUTONOMIC, CARDIOVASCULAR &amp; PHYSIOLOGICAL RESPONSES IN STRENGTH TRAINING PROTOCOLS

ABSTRACT Introduction Strength training is a recurrent practice among several publics and the topic of several studies, yet there is a shortage of previous studies that analyzed these parameters in the same subjects in training sessions involving volume, interval and different repetitions maximum ranges. Objective The study was aimed at measuring and comparing the acute effect of different ST (strength training) protocols on HR (heart rate), HRV (heart rate variability), [LAC] (lactate concentration), [CK] (creatine kinase) and SPE (subjective perceived exertion). Methods Eleven individuals with previous experience were recruited and in three sessions they performed three different training models, namely: high load (4 sets at 90% of 1RM, 180s rest between sets), medium load (3 sets at 75% of 1 RM, 90s rest between sets), and low load (2 sets at 50% of 1 RM, 45s rest between sets) in free squat, bench press, deadlift and bent-over row exercises. Results There was no difference in CK between low load (resistance) and medium load (hypertrophy) (p = 0.60), between resistance and high load (strength) (p = 0.84), and between hypertrophy and strength (p = 0.91), while there was higher lactate accumulation in training with medium and low loads in comparison to training with high loads (p &lt;0.001). Conclusion It can be noted that workouts with high loads, few repetitions and longer intervals (maximum strength) generate lower blood lactate concentrations and SPE values when compared to training with lower loads and shorter intervals (resistance training and hypertrophy). Additionally, when evaluating autonomic and cardiovascular variables, it would appear that manipulating the percentage of 1RM and the interval time does not generate significant changes in HRV, blood pressure (BP) and HR when the repetitions are executed until failure. Level of evidence II; Prospective comparative study.

Internalizing Problems and Attentional Control

Abstract. Individuals with internalizing problems differ in levels of attentional control (AC), and this heterogeneity could be associated with differences in autonomic arousal. The present study investigated whether AC moderated the effect of internalizing problems on self-reported experience and autonomic nervous system (ANS) responses after the induction of negative affect. Children aged 9–13 years were recruited into a patient group (29) and a healthy control group (25). AC was measured by the Early Adolescent Temperament Questionnaire. Heart rate, heart rate variability (HRV) and pre-ejection period (PEP) were recorded during baseline, a sad film clip and recovery, and analyzed using a marginal linear model. Children reported their experienced emotion, valence, and arousal in response to the film. A significant interaction effect showed increased HRV and longer PEP from baseline to recovery for patients with higher AC. Patients with lower AC showed increased HRV followed by a return to baseline values after the film clip and no significant changes in PEP. Healthy controls showed no significant changes in HRV or PEP independent of level of AC. There were no differences between groups in self-reported experience. The results indicate that AC moderated the effect of internalizing problems on ANS regulation. Increased HRV and longer PEP from baseline to recovery were uniquely associated with higher AC and internalizing problems. This physiological response might indicate a cognitive avoidance strategy. AC could be an important factor explaining heterogeneity in ANS activity among individuals with internalizing problems. Clinical implications of the present findings are discussed.

Novel heart rate variability index for wrist-worn wearable devices subject to motion artifacts that complicate measurement of the continuous pulse interval

Objective: Wearable health monitoring devices have recently become popular, but they can still only measure the average heart rate. Heart rate variability (HRV) is known to represent changes in the autonomic nervous system and analysis of HRV has the potential to be used for monitoring various wellness-related parameters such as sleep or stress. HRV analysis requires accurate measurement of the heartbeat interval. In wearable devices, it is difficult to accurately measure the heartbeat interval due to motion noise. In this paper we propose a new method for performing HRV analysis on photoplethysmographic (PPG) signals corrupted by motion artifacts measured at the wrist. Approach: A frequency-tracking algorithm based on the oscillator-based adaptive notch filter was used to measure instantaneous heart rate. The algorithm consists of a time-varying bandpass filter for enhancing the heartbeat signal and an adaptive mechanism for tracking heart rate frequency. By optimizing the filter bandwidth and forgetting factor of the adaptive mechanism, the frequency-tracking algorithm better reflects the variability of instantaneous heart rate. The new HRV index was calculated as the standard deviation of the heartbeat interval data converted using the heart rate estimated by the frequency-tracking algorithm. In order to verify the effectiveness of the proposed index, the new HRV index calculated for each sleep stage was compared with SDNN, the standard deviation of the heartbeat interval, which was calculated using simultaneous electrocardiogram measurements. In addition, changes in SDNN and the new index were compared during a socially evaluated speech task. Finally, the relationship between the new index and SDNN was compared with the data collected during daily activities over a 24 h period. Main results: Experimental results showed that statistically significant changes in HRV could be monitored in different sleep stages using the proposed method. In addition, when subjects were stressed by a socially evaluated speech task, significant reduction in HRV was observed using the proposed method. Finally, HRV values measured during daily activities over a 24 h period showed a high correlation coefficient of 0.812 with reference HRVs. Significance: The new HRV index calculated by the proposed method is expected to be an effective new solution for noisy PPG signals.

An investigation on the influence of yogic methods on heart rate variability.

The role of underlying mechanisms of yogic strategies which exert beneficiary effects on cardiac autonomic control is poorly understood. We have performed heart rate variability (HRV) analysis on subjects performing yogic methods and control subjects who mimic them through paced breathing and focused attention tasks using external cues. Heart rate (HR) time series is generated from electrocardiogram measured from subjects of yogic group (YG); performing yogic practices (n=15), paced breathing group (PBG); involved in breathing exercises cued at breathing rates (BR) from 3 to 15 cycles per minute (cpm) (n=23), normal breathing group (NBG) under regular breathing (n=15), and subjects performing three different cognitive tasks designated as focused attention group (FAG), (n=24). HRV is analyzed using coherence plots, spectrograms, HRV parameters, and instantaneous frequency recurrence plots (IFRP). HRV is similar among YG and PBG (at BR <12cpm) and significantly different for YG vs. NBG (p<0.001) and PBG vs. NBG (p<0.001). Regularity of breathing oscillations observed in HR is quantified using IFRP and is identical among FAG, PBG, and YG and significantly different for YG vs. NBG (p<0.01), PBG vs. NBG (p<0.01), and FAG vs. NBG (p<0.05). Low-frequency breathing (BR <12cpm) plays a primary role in eliciting physiologically significant changes in HRV. By identifying a similarity in breathing oscillations of HR of FAG, YG, and PBG, the results recognize the coexistence of attention and breathing strategies and postulate their joint role in sustaining autonomic benefits, while effects induced by breathing alone on HRV could be attained even intermittently.

The Effects of Subconcussive Impacts on Heart Rate Variability In Female Youth Soccer Players

BackgroundANS function can be measured noninvasively and relatively inexpensively through heart rate variability (HRV). Reduced HRV is representative of an uncoupling between the ANS and cardiovascular system, which may be proportional to the severity of a neurological injury. Reduced HRV has been observed in patients diagnosed with a sport‐related concussion, and therefore may be a useful outcome measure in identifying the chronic effects of heading during a youth soccer season.ObjectivesThe purpose of this study was to evaluate the effects of one season of competitive soccer, with the inherent subconcussive header impacts, on autonomic function in female youth soccer players.ParticipantsTwenty‐three female youth soccer players (13.4 ± 0.84 years old) were recruited from three competitive soccer teams.MethodsThe number of headers performed during the season were quantified using game video analysis. Players that performed fewer than the average number of headers (20) at the end of the season were classified into the “low header” group (N=13), while players with 20 or more headers at the end of the season were classified into the “high header” group (N=10). A five‐minute resting electrocardiogram data was collected from all players at baseline and post‐season. These data were analyzed using a two‐way mixed ANOVA in order to calculate heart rate variability time‐domain and frequency‐domain measures, which included mean heart rate, standard deviation of the N‐N interval, total power, low frequency, high frequency, and low to high frequency ratio (LF/HF).ResultsThere was a statistically significant interaction between time and group for LF/HF from preseason (6.24 ± 5.77; 2.96 ± 1.81) to postseason (6.79 ± 6.75; 1.90 ± 1.02) in the low and high header groups, respectively (p=.024, partial h2=0.313). There were no other statistically significant changes in HRV for any other time or frequency domain outcome measure.ConclusionOur preliminary findings indicate that the LF/HF in the high header group differed from the low header group over the course of a soccer season. This may indicate that an increased number of chronic head impacts might result in an imbalance between sympathetic and parasympathetic activity, which would signify an alteration in autonomic function. These preliminary results demonstrate that additional research is needed in order to further understand the effects of heading on ANS function.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.