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Background/Objectives: The autonomic nervous system (ANS) is considered one of the mechanisms mediating the benefits of whole-body cold stimulation (WBC). Nevertheless, different treatment protocols, different methodologies employed to assess the ANS, and, in particular, difficulties in interpreting the numerous variables obtained represent important barriers to understanding the effects of WBC on the ANS. The present study aimed to explore the effects of WBC on cardiac autonomic control (CAR) as assessed using a single composite percentile-ranked proxy of autonomic balance (ANSI), considering two different WBC temperatures and the same WBC protocol. Methods: Heart rate variability (HRV) was employed to assess the ANS in 23 subjects with obesity who underwent 10 WBC sessions, studied before and after 2 min WBC at −55 °C (15 subjects) or 2 min WBC at −110 °C (8 subjects) both at the first session (T1) and the last one (T10). To overcome some important barriers in data interpretation and age/sex bias, we considered the Autonomic Nervous System Index (ANSI), a single composite percentile-ranked proxy of autonomic control. Results: We observed an improvement in CAR independently of the employed temperature. Both treatments, without distinction, caused a significant increase in the ANSI post-WBC treatment both at T1 and T10 and a significant betterment of the total power of the RR interval variability from pre- to post-treatment at T1 and overall from T1 to T10. Conclusions: WBC was capable of inducing an immediate change in the ANS control (pre- vs. post-treatment both at T1 and T10) and a long-term modulation in cardiac autonomic control (T1-pre vs. T10-pre). [ABSTRACT FROM AUTHOR]

The objectives of the study were (i) to evaluate the effects of whole‐body cryostimulation (WBC) after training as an effective tool to improve sleep and recovery and (ii) to determine which exposure schedule for WBC (immediately after training vs. 1h before bedtime) is the most appropriate to improve sleep and recovery. Twenty‐two well‐trained male athletes or triathletes (23.1 ± 3.5‐years) were recruited in this controlled crossover protocol. Each participant completed the three experimental sessions, each composed of a running training session and one night of sleep analysis. Depending on the experimental condition, subjects were exposed—or not (CONT)—to WBC immediately after training (CRYO 7 p.m.) or 1h before going to bed (CRYO 10 p.m.). All participants were randomly assigned to each condition, spaced seven days apart. Sleep was monitored via actimetry, cerebral activity recordings, heart rate variability, body core temperature, and perceptual measurements. WBC after training did not modify subjective or objective sleep parameters compared to the control condition. However, WBC significantly improved cardiac parasympathetic activity. More specifically, it was more activated during the night following the CRYO 10 p.m. condition than in the other experimental conditions. Core body temperature (CBT) 1h after bedtime was the lowest in the CRYO 10 p.m. condition. This study confirmed the effectiveness of WBC as a recovery technique after intense evening training. We suggest that WBC may exhibit the most significant benefit on recovery if the session is performed 1h before bedtime, acting on subsequent parasympathetic activation and CBT drop. Highlights: Cryotherapy improves sleep through better parasympathetic activation.Time of exposure affects sleep parameters differently.An exposure to cryostimulation close to sleep (at 10 p.m.) improves parasympathetic activation even more than an exposure just after training (at 7 p.m.).An exposure to cryostimulation close to sleep (at 10 p.m.) decreases the internal temperature to a greater extent than an exposure just after training (at 7 p.m.). [ABSTRACT FROM AUTHOR]

Introduction: Tobacco use and exposure to Second-Hand Smoke (SHS) are major health hazards for growing children and adolescents. Smokeless Tobacco (SLT) product consumption is a serious health issue both abroad and in India. Children and young people are more likely to be exposed to Secondhand Smoke (SHS) in India due to high population density. Aim: To assess physical anthropometric parameters and cardiac autonomic function tests among passive smokers and SLT users. Materials and Methods: This cross-sectional study was conducted in the department of Physiology Nootan Medical College and Research Centre, Visnagar from August 2023 to February 2024. The study was comprised of 100 participants including 50 non-smokers who chew tobacco and who have never been a passive smoker in Group-A (SLT) and 50 age-matched passive smokers who lived with at least one smoker or frequently interacted with smokers at work for at least three years before conducting this study was included in Group-B (Passive smoke or SHS). Anthropometric measurements were recorded. Cardiac autonomic function tests were done by using a Polyrite recording machine with mode “ECG” in Lead-II position among both groups. Results were expressed as mean±Standard Deviation (SD), and analysed by using unpaired student’s t-test. The p-value of

Alzheimer's disease, the most common form of dementia among older adults, slowly destroys memory and thinking skills. In recent years, scientists have made tremendous progress in understanding Alzheimer's disease, still, they do not yet fully understand what causes the disease. This article proposes a novel etiology for Alzheimer's disease. Our hypothesis developed from a review of nuclear medicine scans, in which the authors observed a significant increase in nasal turbinate vasodilation and blood pooling in patients with hypertension, sleep apnea, diabetes and/or obesity, all risk factors for Alzheimer's disease. The authors propose that nasal turbinate vasodilation and resultant blood pooling lead to the obstruction of normal nasal lymphatic clearance of cerebrospinal fluid and its waste products from the brain. The nasal turbinate vasodilation, due to increased parasympathetic activity, occurs alongside the well-established increased sympathetic activity of the cardiovascular system as seen in patients with hypertension. The increased parasympathetic activity is likely due to an autonomic imbalance secondary to the increase in worldwide consumption of highly processed food associated with dysregulation of the glucose regulatory system. The authors' hypothesis offers a novel mechanism and a new paradigm for the etiology of Alzheimer's disease and helps explain the rapid worldwide rise in the disease and other dementias which are expected to double in the next 20 years. This new paradigm provides compelling evidence for the modulation of the parasympathetic nervous system as a novel treatment strategy for Alzheimer's disease and other degenerative brain diseases, specifically targeting nasal turbinate lymphatic flow. [ABSTRACT FROM AUTHOR]

Introduction: Tobacco use and exposure to Second-Hand Smoke (SHS) are major health hazards for growing children and adolescents. Smokeless Tobacco (SLT) product consumption is a serious health issue both abroad and in India. Children and young people are more likely to be exposed to Secondhand Smoke (SHS) in India due to high population density. Aim: To assess physical anthropometric parameters and cardiac autonomic function tests among passive smokers and SLT users. Materials and Methods: This cross-sectional study was conducted in the department of Physiology Nootan Medical College and Research Centre, Visnagar from August 2023 to February 2024. The study was comprised of 100 participants including 50 non-smokers who chew tobacco and who have never been a passive smoker in Group-A (SLT) and 50 agematched passive smokers who lived with at least one smoker or frequently interacted with smokers at work for at least three years before conducting this study was included in Group-B (Passive smoke or SHS). Anthropometric measurements were recorded. Cardiac autonomic function tests were done by using a Polyrite recording machine with mode "ECG" in Lead-II position among both groups. Results were expressed as mean±Standard Deviation (SD), and analysed by using unpaired student's t-test. The p-value of <0.05 was considered as statistically significant. Results: Resting (Basal) heart rate was significantly increased in the SLT group (p-value=0.001). Resting Systolic Blood Pressure (SBP) was significantly reduced in the passive smoker group when compared to SLT group (p-value=0.001). It was noted that 30:15 ratio was statistically significant in the passive smokers as compared to that in the SLT group (p-value=0.001). It was also noted that blood pressure response to immediate standing in passive smokers was highly significant (p-value=0.001). Conclusion: The results of present study showed that sympathetic activity was increased and parasympathetic activity was decreased in tobacco users (SLT). The fall of SBP in response to immediate standing among passive smokers is suggestive of decreased central sympathetic activity and baroreceptor reflex sensitivity. [ABSTRACT FROM AUTHOR]

The time-resolved analysis of heart rate (HR) and heart rate variability (HRV) is crucial for the evaluation of the dynamic changes of autonomic activity under different clinical and behavioural conditions. Standard HRV analysis is performed in the frequency domain because the sympathetic activations tend to increase low-frequency HRV oscillations, while the parasympathetic ones increase high-frequency HRV oscillations. However, a strict separation of HRV into frequency bands may cause biased estimations, especially in the low-frequency range. To overcome this limitation, we propose a robust estimator that combines HR and HRV dynamics, based on the correlation of the Poincaré plot descriptors of interbeat intervals from the electrocardiogram. To validate our method, we used electrocardiograms gathered from open databases where standardized paradigms were applied to elicit changes in autonomic activity. Our proposal outperforms the standard spectral approach for the estimation of low- and high-frequency fluctuations in HRV, and its performance is comparable with newer methods. Our method constitutes a valuable, robust, time-resolved and cost-effective tool for a better understanding of autonomic activity through HR and HRV in a healthy state and potentially for pathological conditions.

Simple Summary: Transcutaneous auricular vagal nerve stimulation is a non-invasive technique used in human medicine to prevent or treat post-operative ileus. The vagus nerve plays a crucial role in increasing intestinal motility and reducing the inflammatory response in sepsis models; thus, its stimulation constitutes an attractive strategy for modulating intestinal motility and immune response after abdominal surgery in both humans and horses. The technique has never been described in the equine species before. This study describes transcutaneous auricular vagal nerve stimulation in healthy non-sedated horses, assessing its feasibility and effect on heart rate variability (HRV). HRV was analysed as an indirect method to identify parasympathetic stimulation of the treatment. Auricular vagal nerve stimulation is an economical procedure that is easy to perform. However, it was poorly tolerated in awake horses. In the mares that tolerated the procedure, its effect on the autonomic system confirmed the potential stimulation of vagal activity, which can be of interest in preventing post-operative ileus in horses with inflammation or after exploratory laparotomy. This study aimed to evaluate the feasibility of transcutaneous auricular vagal nerve stimulation (tAVNS) in healthy horses and its effect on heart rate variability (HRV). The study comprised three phases: the selection of mares, their acclimatization to the tAVNS, and the stimulation phase. Stimulation was performed with two electrodes positioned on the right pinna. The settings were 0.5 mA, 250 μs, and 25 Hz for pulse amplitude, pulse width, and pulse frequency, respectively. HRV was analysed before (B1), during (T), and after (B2) the tAVNS. From the 44 mares initially included, only 7 completed the three phases. In these mares, the heart rate (HR) was significantly lower, and frequency domain parameters showed an increased parasympathetic tone in B2 compared with B1. However, in 3/7 mares, the HR was significantly higher during T compared with B1 and B2, compatible with a decreased parasympathetic tone, while in 4/7 mares, the HR was significantly lower and the parasympathetic nervous system index was significantly higher during T and B2 compared with B1. The tAVNS is an economical and easy procedure to perform and has the potential to stimulate vagal activity; however, it was poorly tolerated in the mares included in this study. [ABSTRACT FROM AUTHOR]

Alzheimer’s disease, the most common form of dementia among older adults, slowly destroys memory and thinking skills. In recent years, scientists have made tremendous progress in understanding Alzheimer’s disease, still, they do not yet fully understand what causes the disease. This article proposes a novel etiology for Alzheimer’s disease. Our hypothesis developed from a review of nuclear medicine scans, in which the authors observed a significant increase in nasal turbinate vasodilation and blood pooling in patients with hypertension, sleep apnea, diabetes and/or obesity, all risk factors for Alzheimer’s disease. The authors propose that nasal turbinate vasodilation and resultant blood pooling lead to the obstruction of normal nasal lymphatic clearance of cerebrospinal fluid and its waste products from the brain. The nasal turbinate vasodilation, due to increased parasympathetic activity, occurs alongside the well-established increased sympathetic activity of the cardiovascular system as seen in patients with hypertension. The increased parasympathetic activity is likely due to an autonomic imbalance secondary to the increase in worldwide consumption of highly processed food associated with dysregulation of the glucose regulatory system. The authors’ hypothesis offers a novel mechanism and a new paradigm for the etiology of Alzheimer’s disease and helps explain the rapid worldwide rise in the disease and other dementias which are expected to double in the next 20 years. This new paradigm provides compelling evidence for the modulation of the parasympathetic nervous system as a novel treatment strategy for Alzheimer’s disease and other degenerative brain diseases, specifically targeting nasal turbinate lymphatic flow.

Abstract Background Osteoarthritis (OA) is a chronic degenerative joint disease causing limited mobility and pain, with no curative treatment available. Recent in vivo studies suggested autonomic alterations during OA progression in patients, yet clinical evidence is scarce. Therefore, autonomic tone was analyzed in OA patients via heart rate variability (HRV) measurements. Methods Time-domain (SDRR, RMSSD, pRR50) and frequency-domain (LF, HF, LF/HF) HRV indices were determined to quantify sympathetic and parasympathetic activities. In addition, perceived stress, WOMAC pain as well as serum catecholamines, cortisol and dehydroepiandrosterone-sulphate (DHEA-S) were analyzed. The impact of the grade of disease (GoD) was evaluated by linear regression analysis and correlations with clinical data were performed. Results GoD significantly impacted the autonomic tone in OA patients. All time-domain parameters reflected slightly decreased HRV in early OA patients and significantly reduced HRV in late OA patients. Moreover, frequency-domain analysis revealed decreased HF and LF power in all OA patients, reflecting diminished parasympathetic and sympathetic activities. However, LF/HF ratio was significantly higher in early OA patients compared to late OA patients and implied a clear sympathetic dominance. Furthermore, OA patients perceived significantly higher chronic stress and WOMAC pain levels compared to healthy controls. Serum cortisol and cortisol/DHEA-S ratio significantly increased with GoD and positively correlated with WOMAC pain. In contrast, serum catecholamines only trended to increase with GoD and pain level. Conclusions This prospective study provides compelling evidence of an autonomic dysfunction with indirect sympathetic dominance in early and late knee OA patients for the first time based on HRV analyses and further confirmed by serum stress hormone measurements. Increased sympathetic activity and chronic low-grade inflammation in OA as well as in its major comorbidities reinforce each other and might therefore create a vicious cycle. The observed autonomic alterations coupled with increased stress and pain levels highlight the potential of HRV as a prognostic marker. In addition, modulation of autonomic activity represents an attractive future therapeutic option. Graphical abstract

Background: Osteoarthritis (OA) is a chronic degenerative joint disease causing limited mobility and pain, with no curative treatment available. Recent in vivo studies suggested autonomic alterations during OA progression in patients, yet clinical evidence is scarce. Therefore, autonomic tone was analyzed in OA patients via heart rate variability (HRV) measurements. Methods: Time-domain (SDRR, RMSSD, pRR50) and frequency-domain (LF, HF, LF/HF) HRV indices were determined to quantify sympathetic and parasympathetic activities. In addition, perceived stress, WOMAC pain as well as serum catecholamines, cortisol and dehydroepiandrosterone-sulphate (DHEA-S) were analyzed. The impact of the grade of disease (GoD) was evaluated by linear regression analysis and correlations with clinical data were performed. Results: GoD significantly impacted the autonomic tone in OA patients. All time-domain parameters reflected slightly decreased HRV in early OA patients and significantly reduced HRV in late OA patients. Moreover, frequency-domain analysis revealed decreased HF and LF power in all OA patients, reflecting diminished parasympathetic and sympathetic activities. However, LF/HF ratio was significantly higher in early OA patients compared to late OA patients and implied a clear sympathetic dominance. Furthermore, OA patients perceived significantly higher chronic stress and WOMAC pain levels compared to healthy controls. Serum cortisol and cortisol/DHEA-S ratio significantly increased with GoD and positively correlated with WOMAC pain. In contrast, serum catecholamines only trended to increase with GoD and pain level. Conclusions: This prospective study provides compelling evidence of an autonomic dysfunction with indirect sympathetic dominance in early and late knee OA patients for the first time based on HRV analyses and further confirmed by serum stress hormone measurements. Increased sympathetic activity and chronic low-grade inflammation in OA as well as in its major comorbidities reinforce each other and might therefore create a vicious cycle. The observed autonomic alterations coupled with increased stress and pain levels highlight the potential of HRV as a prognostic marker. In addition, modulation of autonomic activity represents an attractive future therapeutic option. [ABSTRACT FROM AUTHOR]

* Heart rate variability (HRV) operationalizes the successive beat-to-beat fluctuations over a defined period of time, is derived from the time series of successive R-R intervals using various context-dependent metrics, and reflects the complex dynamic modulation of the heart's chronotropic response to physiological and/or pathological perturbations. * HRV metrics are used as markers of human cardiovascular health and risk stratification, or as measures of load quantification, exercise response and performance, respectively. * However, a valid use of HRV in the fields of sports medicine and exercise science requires careful consideration of the specific measurement principle of the recording device, standardized assessment, preprocessing, analysis, and context-sensitive interpretation. [ABSTRACT FROM AUTHOR]

Hypertension affects an estimated 1.3 billion people worldwide and is considered the number one contributor to mortality via stroke, heart failure, renal failure, and dementia. Although the physiologic mechanisms leading to the development of essential hypertension are poorly understood, the regulation of cerebral perfusion has been proposed as a primary cause. This article proposes a novel etiology for essential hypertension. Our hypothesis developed from a review of nuclear medicine scans, where the authors observed a significantly abnormal increase in nasal turbinate vasodilation in hypertensive patients using quantitative region of interest analysis. The authors propose that nasal turbinate vasodilation and resultant blood pooling obstruct the flow of cerebrospinal fluid passing through nasal turbinate lymphatics, thereby increasing intracranial pressure. The authors discuss the glymphatic/lymphatic clearance system which is impaired with age, and at which time hypertension also develops. The increased intracranial pressure leads to compensatory hypertension via Cushing’s mechanism, i.e., the selfish brain hypothesis. The nasal turbinate vasodilation, due to increased parasympathetic activity, occurs simultaneously along with the well-established increased sympathetic activity of the cardiovascular system. The increased parasympathetic activity is likely due to an autonomic imbalance secondary to the increase in worldwide consumption of processed food. This hypothesis explains the rapid worldwide rise in essential hypertension in the last 50 years and offers a novel mechanism and a new paradigm for the etiology of essential hypertension. This new paradigm offers compelling evidence for the modulation of parasympathetic nervous system activity as a novel treatment strategy, specifically targeting nasal turbinate regulation, to treat diseases such as hypertension, idiopathic intracranial hypertension, and degenerative brain diseases. The proposed mechanism of essential hypertension presented in this paper is a working hypothesis and confirmatory studies will be needed.

Background Renal blood flow (RBF) is regulated by an autonomic nervous system and is reduced in older adults. Massage has been previously found to increase blood flow. Objective This two-armed double-blind, randomized controlled trial aimed to investigate the immediate effects of Thai foot massage (TFM) on RBF, psychological stress, and heart rate variability (HRV) in older adult persons. Material and Methods The 26 healthy older adult volunteers were recruited and randomly assigned to the TFM group (13 persons) and the control group (13 persons). The TFM group received a 15-minute Thai foot massage, and the control group received a 15-minute bed rest. Primary outcomes – RBF parameters [peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI), volumetric arterial blood flow (VF)] and secondary outcomes – HRV parameters [standard deviation of the normal-to-normal intervals (SDNN), root mean square of successive differences (RMSSD), high frequency (HF), low frequency (LF), and low frequency per high frequency (LF/HF)] were measured after each intervention. Results Results showed that the VF significantly increased after TFM (P < 0.05) but not in control. Meanwhile, the stress index significantly reduced after TFM (P < 0.05). SDNN and RMSSD, the proxies of parasympathetic activity, also significantly increased in the TFM group (p < 0.05). Only RMSSD was significantly enhanced in the control group. No side effects were observed. Conclusion The TFM could increase RBF and alleviate psychological stress through parasympathetic activity actuation. Therefore, this intervention might improve RBF and relieve stress in the older population. Further study should be carried out on a larger population.

Background: Altered autonomic modulation, measured by heart rate variability (HRV), has been found to be associated with dementia risk in the elderly. However, long-term follow-up study evaluating the association between autonomic modulation from middle-age and the incidence of dementia has been limited. Methods: This retrospective cohort analyzed data from Taiwan's National Health Insurance Database covering the period from 2001 to 2017, with a linkage to citywide health examinations conducted by Tainan Metropolitan City, Taiwan. We included subjects aged 45–64 years. The mean follow-up period was 15.75 ± 3.40 years. The measurements of HRV included resting heart rate, high frequency (HF), low frequency (LF), standard deviation of normal-to-normal R–R intervals (SDNN), ratio between the 30th and 15th R–R interval after standing up from the supine position (30/15 ratio), ratio between the R–R intervals during expiration and inspiration, and the ratio between the high- and low-frequency components (LF/HF). The main study outcome was the incidence of dementia. We performed multivariable Cox proportional hazard regression models to compare the risk of dementia among different HRV subgroups. Results: We included 565 participants with a mean age of 53 (SD: 6) years, of whom 44% were male. The risk of dementia was significantly increased in association with lower parasympathetic HRV modulation, including SDNN (HR: 3.23, 95% CI: 1.55–6.73) and 30/15 ratio (HR: 3.52, 95%CI: 1.67–7.42). Moreover, the risk of dementia was increased in subjects with higher LF/HF ratios (HR: 2.05, 95% CI: 1.12–3.72). Conclusions: Lower parasympathetic activity and higher sympathetic-vagal imbalance in middle-age were associated with dementia risk.

Objective: We aimed to identify parasympathetic and emotional alterations, as indicated by the heart rate variability (HRV) and Brunel mood scale (BRUMS), after long-term exposure to theta binaural beats (BB) for 10 minutes daily. Methods: Recruited healthy subjects (n = 60) were equally split into the experimental and control groups. HRVs were measured over three visits spaced out by two weeks. At each visit, HRV was measured for two minutes before, ten minutes during, and two minutes after listening. Results: The root-mean-square of differences between successive RR intervals (RMSSD) and the percentage of adjacent RR intervals with a difference greater than 50 ms (pNN50) were significantly increased during 6-Hz BB listening at 4–10 minutes at all three visits, but high frequency (HF) HRV was increased at the second and third visits. After 6-Hz BB listening, there were significant increases in RMSSD and pNN50 at the second and third visits, and in HF HRV at the third visit. BRUMS demonstrated a significant decrease in both positive and negative moods after listening to 6-Hz BB on the first visit. However, after two and four weeks, BRUMS demonstrated a significant decrease in only negative mood. Conclusion: A minimum of four minutes of 6-Hz BB could be beneficial to improve relaxation during listening. Nevertheless, considering the aftereffects, two weeks of daily listening might be required to achieve deep relaxation without vigor reduction. Significance: Optimal duration and practice of BB listening are the keys to achieving better relaxation and parasympathetic tone in healthy listeners.

BackgroundSecond-degree atrioventricular (AV) block at rest is very common in horses. The underlying molecular mechanisms are unexplored, but commonly attributed to high vagal tone.AimTo assess whether AV block in horses is due to altered expression of the effectors of vagal signalling in the AV node, with specific emphasis on the muscarinic acetylcholine receptor (M2) and the G protein-gated inwardly rectifying K+ (GIRK4) channel that mediates the cardiac IK,ACh current.MethodEighteen horses with a low burden of second-degree AV block (median 8 block per 20 h, IQR: 32 per 20 h) were assigned to the control group, while 17 horses with a high burden of second-degree AV block (median: 408 block per 20 h, IQR: 1,436 per 20 h) were assigned to the AV block group. Radiotelemetry ECG recordings were performed to assess PR interval and incidence of second-degree AV block episodes at baseline and on pharmacological blockade of the autonomic nervous system (ANS). Wenckebach cycle length was measured by intracardiac pacing (n = 16). Furthermore, the expression levels of the M2 receptor and the GIRK4 subunit of the IKACh channel were quantified in biopsies from the right atrium, the AV node and right ventricle using immunohistochemistry and machine learning-based automated segmentation analysis (n = 9 + 9).ResultsThe AV block group had a significantly longer PR interval (mean ± SD, 0.40 ± 0.05 s; p

This study aimed to evaluate the feasibility of transcutaneous auricular vagal nerve stimulation (tAVNS) in healthy horses and its effect on heart rate variability (HRV). The study comprised three phases: the selection of mares, their acclimatization to the tAVNS, and the stimulation phase. Stimulation was performed with two electrodes positioned on the right pinna. The settings were 0.5 mA, 250 μs, and 25 Hz for pulse amplitude, pulse width, and pulse frequency, respectively. HRV was analysed before (B1), during (T), and after (B2) the tAVNS. From the 44 mares initially included, only 7 completed the three phases. In these mares, the heart rate (HR) was significantly lower, and frequency domain parameters showed an increased parasympathetic tone in B2 compared with B1. However, in 3/7 mares, the HR was significantly higher during T compared with B1 and B2, compatible with a decreased parasympathetic tone, while in 4/7 mares, the HR was significantly lower and the parasympathetic nervous system index was significantly higher during T and B2 compared with B1. The tAVNS is an economical and easy procedure to perform and has the potential to stimulate vagal activity; however, it was poorly tolerated in the mares included in this study.

ObjectiveA novel protocol for paired associative stimulation (PAS), called high PAS, consists of high-intensity transcranial magnetic stimulation (TMS) and high-frequency peripheral nerve stimulation (PNS). High PAS was developed for spinal cord injury rehabilitation and targets plastic changes in stimulated pathways in the corticospinal tract, which improves motor function. As therapy interventions can last many weeks, it is important to fully understand the effects of high PAS, including its effect on the cardiovascular system. Heart rate variability (HRV) has been used to measure changes in both sympathetic and parasympathetic systems.MethodsWe used short-term HRV measurements to evaluate the effects of one 20-min session of high PAS on 17 healthy individuals. HRV was recorded for 5 min before (PRE), during (STIM), immediately after (POST), 30 min after (POST30), and 60 min after (POST60) the stimulation. Five participants repeated the HRV setup with sham stimulation.ResultsA significant decrease in low-frequency (LF) power (n.u.) (p = 0.002), low-frequency to high-frequency (HF) ratio (p = 0.017), in Poincaré plot [the standard deviation of RR intervals perpendicular to (SD1) and along (SD2) the line of identity SD2/SD1 ratio p

Mild hyperbaric oxygen (HBO) enhances oxygen absorption in blood, relieving fatigue without causing oxidative stress. The benefits of mild HBO have been recognized in the treatment of lifestyle-related diseases and hypertension, but no research has been conducted on its effects on immunity. The aim of the present study is to investigate the effect of mild HBO on natural killer (NK) cells and cytokines in healthy young women. This crossover randomized control trial was conducted with 16 healthy young women. Participants were randomly exposed to normobaric oxygen (NBO; 1.0 atmospheres absolute (ATA), 20.8% oxygen) and mild HBO conditions (1.4 ATA, 35–40% oxygen, injected 18L oxygen per minute) in a hyperbaric oxygen chamber for 70 min. Heart rate, parasympathetic activity, NK cell count, interleukin (IL)-6, IL-12p70 and derivatives of reactive oxygen metabolites (d-ROMs) were measured before and after both exposures. In the NBO condition, parasympathetic activity remained unchanged, whereas after mild HBO exposure, parasympathetic activity was significantly increased. NK cells remained unchanged after NBO exposure, while NK cells were increased after exposure to mild HBO. Exposure to mild HBO did not increase d-ROM values, IL-6 and IL-12p70 protein levels. These findings suggest that exposure to mild HBO can be a useful protocol to increase NK cells by regulating parasympathetic activity via increasing oxygen delivery. [ABSTRACT FROM AUTHOR]

The positive association between heart rate variability and cardiorespiratory fitness in youth populations is unclear. In this regard, several methodological aspects related to heart rate variability analysis could partially explain the disagreement between studies. To the best of the authors' knowledge, the influence of the heart rate on data analysis is unclear. In the present short communication, we discuss the impact of the heart rate on the associations between heart rate variability and cardiorespiratory fitness in youth. In addition, we proposed some aspects that should be considered for statistical analyses when the relationship between heart rate variability and cardiorespiratory fitness is studied. Finally, we should acknowledge that these recommendations may be applicable for other health-related outcomes different than cardiorespiratory fitness (e.g., inflammatory markers, cognition, cardiovascular disease status). [ABSTRACT FROM AUTHOR]

Purpose: The aim of the current study was to evaluate changes in choroidal circulation hemodynamics after periocular skin warming at 40°C using laser speckle flowgraphy (LSFG)., Methods: Twenty-four right eyes of 24 healthy participants were included. Changes in choroidal circulation hemodynamics were determined using LSFG to evaluate the mean blur rate (MBR) of the macula, which represents choroidal blood flow velocity. Systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), heart rate (HR), ocular perfusion pressure (OPP), and subfoveal choroidal thickness (SCT) were also measured, and sympathetic nerve status was assessed via salivary α-amylase (sAA) activity at baseline and after periocular skin warming., Results: Immediately after warming, SBP, DBP, MBP, HR, OPP, sAA activity, and MBR were significantly lower than baseline. SCT was significantly increased., Conclusion: In the normal eye, the decrease in sympathetic nerve activity induced by the relaxing effects of periocular skin warming reduces systemic circulatory activity and choroidal circulatory dynamics., Competing Interests: Human subjects: Consent for treatment and open access publication was obtained or waived by all participants in this study. Ethics Committee of Fukuoka International University of Health and Welfare issued approval 21-fiuhw-003. The study adhered to the tenets of the Declaration of Helsinki. Animal subjects: All authors have confirmed that this study did not involve animal subjects or tissue. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: This work was supported by JSPS KAKENHI Grant Number JP23K10818. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Ujita et al.)

Objective: Identifying new modifiable prognostic markers is important for ovarian cancer (OC). Low parasympathic activity is associated with inflammation, oxidative stress and sympathetic nervous system activation. Previous studies reported that low vagal nerve activity, measured by low heart rate variability (HRV), may predict poor cancer prognosis. We aimed to examine the prognostic value of HRV in OC. Methods: This bicentric retrospective study included patients diagnosed with serous OC FIGO stage ≥IIB, between January 2015 and August 2019, with electrocardiograms (ECG) available around diagnosis. HRV was measured from ECG using the time domain parameter of standard deviation of all normal-tonormal heartbeat intervals (SDNN). Optimal SDNN cut-off was determined using the Youden index criteria of time-dependent ROC curves. We used multivariate cox proportional hazard models to investigate the association between HRV and overall survival (OS), while adjusting for well-known OC prognostic factors. Results: The 202 patients included were 65.7 years-old on average, 93% had stage FIGO IIIC/IV, 56% had complete surgical resection. Median OS was 38.6 months [95%CI:34.4-47.4]. The median SDNN was 11.1ms, with an optimal cutoff of 10ms to predict OS. OS was shorter for patients with low HRV compared to high HRV (26.4 vs 45.1 months; p<0.001). In multivariate analysis, HRV remained an independent prognostic factor with a two-fold higher risk of death among patients with low SDNN compared to those with high SDNN (HR=2.03, 95%CI=1.35-3.06, p<0.001).Conclusion: Low HRV, was associated with worse OS in OC patients, supporting previous studies on the prognostic role of HRV in cancer. If replicated in prospective studies, vagal nerve activity may be a new therapeutic target in OC. [ABSTRACT FROM AUTHOR]

Stroke prediction is a key health issue for preventive medicine. Atrial fibrillation (AF) detection is well established and the importance of obstructive sleep apneas (OSA) has emerged in recent years. Although autonomic nervous system (ANS) appears strongly implicated in stroke occurrence, this factor is more rarely considered. However, the consequences of decreased parasympathetic activity explored in large cohort studies through measurement of ANS activity indicate that an ability to improve its activity level and equilibrium may prevent stroke. In support of these observations, a compensatory neurostimulation has already proved beneficial on endothelium function. The available data on stroke predictions from ANS is based on many long-term stroke cohorts. These data underline the need of repeated ANS evaluation for the general population, in a medical environment, and remotely by emerging telemedicine digital tools. This would help uncovering the reasons behind the ANS imbalance that would need to be medically adjusted to decrease the risk of stroke. This ANS unbalance help to draw attention on clinical or non-clinical evidence, disclosing the vascular risk, as ANS activity integrates the cumulated risk from many factors of which most are modifiable, such as metabolic inadaptation in diabetes and obesity, sleep ventilatory disorders, hypertension, inflammation, and lack of physical activity. Treating these factors may determine ANS recovery through the appropriate management of these conditions. Natural aging also decreases ANS activity. ANS recovery will decrease global circulating inflammation, which will reinforce endothelial function and thus protect the vessels and the associated organs. ANS is the whistle-blower of vascular risk and the actor of vascular health. Such as, ANS should be regularly checked to help draw attention on vascular risk and help follow the improvements in response to our interventions. While today prediction of stroke relies on classical cardiovascular risk factors, adding autonomic biomarkers as HRV parameters may significantly increase the prediction of stroke. [ABSTRACT FROM AUTHOR]

Introduction: Cardiovascular Autonomic Neuropathy (CAN) may be seen in patients of Type 2 Diabetes Mellitus (T2DM). In many previous studies it was seen that there is reduced heart rate variability in DM patients. Reduced heart rate variability is earliest indicator for the CAN. In different earlier studies, it was found that results of Short-term Heart Rate Variability (HRV) analysis of five minutes is comparable to standard 24 hours HRV analysis. In DM patients CAN is mostly found to be associated with a longer duration of disease, but according to some studies CAN may be present in newly diagnosed diabetes patients also, but the percentage is lower. Aim: To assess the short-term HRV profile as cardiovascular risks among newly diagnosed T2DM patients and to find the correlation of HRV parameters with duration of disease and biochemical parameters; Fasting Plasma Glucose (FPG) and Postprandial Plasma Glucose (PPPG) for early detection and management of CAN. Materials and Methods: The present study was a cross-sectional study conducted in the Department of Physiology in collaboration with the Department of Endocrinology at R.G. Kar Medical College and Hospital, Kolkata, West Bengal, India, from September 2020 to August 2021 on 56 newly diagnosed T2DM (age group 30 to 64 years). Study subjects were grouped according to the Standard deviation of NN intervals (SDNN) (millisecond) value as cardiovascular risk factor. Group 1 was the low risk group, group 2 was the moderate risk group, group 3 was the high-risk group. HRV testing was done with Physiograph Polyrite-D instrument with bio-amplifiers, 4 channels and accessories (RMS latest software-Version 3.0.16) in Autonomic Function Research Laboratory to measure HRV parameters. After collecting data, analysis was done using Statistical Package for Social Sciences (IBM, SPSS) version 23.0 Unpaired student's t-test, Chi-square test, Analysis of Variance (ANOVA) test, Pearson correlation test were performed and statistical significance of different parameters were evaluated. It was considered statistically significant when p-value <0.05. Results: By assessing HRV parameters as cardiovascular risk factors among newly diagnosed T2DM patients the present study showed there was significantly (p-value=0.0065) high LF/HF ratio in males (1.70±1.19) than in females (0.99±0.69). The SDNN value was significantly highest in low cardiovascular risk group (137.29±25.49 ms) and lowest in high cardiovascular risk group (26.07±12.03 ms) (p-value=0.00001). Low Frequency and High Frequency Ratio (LF:HF ratio) was significantly more in age group of 51-60 years. Among all the patients, 34 (61%) patients had increased parasympathetic activity and 22 (39%) subjects had increased sympathetic activity. Female patients showed significantly more increased parasympathetic 24 (75%) activity than males 10 (41.7%). There was a significant association between SDNN values with the duration of disease (p-value=0.004). Conclusion: The present study showed that cardiac autonomic neuropathy is present even at the time of diagnosis of newly diagnosed T2DM as there was sympathovagal imbalance. Female patients have more parasympathetic drive than males which indicates that females are more cardioprotective. [ABSTRACT FROM AUTHOR]

ObjectiveIdentifying new modifiable prognostic markers is important for ovarian cancer (OC). Low parasympathic activity is associated with inflammation, oxidative stress and sympathetic nervous system activation. Previous studies reported that low vagal nerve activity, measured by low heart rate variability (HRV), may predict poor cancer prognosis. We aimed to examine the prognostic value of HRV in OC.MethodsThis bicentric retrospective study included patients diagnosed with serous OC FIGO stage ≥IIB, between January 2015 and August 2019, with electrocardiograms (ECG) available around diagnosis. HRV was measured from ECG using the time domain parameter of standard deviation of all normal-to-normal heartbeat intervals (SDNN). Optimal SDNN cut-off was determined using the Youden index criteria of time-dependent ROC curves. We used multivariate cox proportional hazard models to investigate the association between HRV and overall survival (OS), while adjusting for well-known OC prognostic factors.ResultsThe 202 patients included were 65.7 years-old on average, 93% had stage FIGO IIIC/IV, 56% had complete surgical resection. Median OS was 38.6 months [95%CI:34.4-47.4]. The median SDNN was 11.1ms, with an optimal cut-off of 10ms to predict OS. OS was shorter for patients with low HRV compared to high HRV (26.4 vs 45.1 months; p

Stroke prediction is a key health issue for preventive medicine. Atrial fibrillation (AF) detection is well established and the importance of obstructive sleep apneas (OSA) has emerged in recent years. Although autonomic nervous system (ANS) appears strongly implicated in stroke occurrence, this factor is more rarely considered. However, the consequences of decreased parasympathetic activity explored in large cohort studies through measurement of ANS activity indicate that an ability to improve its activity level and equilibrium may prevent stroke. In support of these observations, a compensatory neurostimulation has already proved beneficial on endothelium function. The available data on stroke predictions from ANS is based on many long-term stroke cohorts. These data underline the need of repeated ANS evaluation for the general population, in a medical environment, and remotely by emerging telemedicine digital tools. This would help uncovering the reasons behind the ANS imbalance that would need to be medically adjusted to decrease the risk of stroke. This ANS unbalance help to draw attention on clinical or non-clinical evidence, disclosing the vascular risk, as ANS activity integrates the cumulated risk from many factors of which most are modifiable, such as metabolic inadaptation in diabetes and obesity, sleep ventilatory disorders, hypertension, inflammation, and lack of physical activity. Treating these factors may determine ANS recovery through the appropriate management of these conditions. Natural aging also decreases ANS activity. ANS recovery will decrease global circulating inflammation, which will reinforce endothelial function and thus protect the vessels and the associated organs. ANS is the whistle-blower of vascular risk and the actor of vascular health. Such as, ANS should be regularly checked to help draw attention on vascular risk and help follow the improvements in response to our interventions. While today prediction of stroke relies on classical cardiovascular risk factors, adding autonomic biomarkers as HRV parameters may significantly increase the prediction of stroke.

Abstract Background Association of physiological recovery with nutrition has scarcely been studied. We investigated whether physiological recovery during sleep relates to eating habits, i.e., eating behaviour and diet quality. Methods Cross-sectional baseline analysis of psychologically distressed adults with overweight (N = 252) participating in a lifestyle intervention study in three Finnish cities. Recovery measures were based on sleep-time heart rate variability (HRV) measured for 3 consecutive nights. Measures derived from HRV were 1) RMSSD (Root Mean Square of the Successive Differences) indicating the parasympathetic activation of the autonomic nervous system and 2) Stress Balance (SB) indicating the temporal ratio of recovery to stress. Eating behaviour was measured with questionnaires (Intuitive Eating Scale, Three-Factor Eating Questionnaire, Health and Taste Attitude Scales, ecSatter Inventory™). Diet quality was quantified using questionnaires (Index of Diet Quality, Alcohol Use Disorders Identification Test Consumption) and 48-h dietary recall. Results Participants with best RMSSD reported less intuitive eating (p = 0.019) and less eating for physical rather than emotional reasons (p = 0.010) compared to those with poorest RMSSD; participants with good SB reported less unconditional permission to eat (p = 0.008), higher fibre intake (p = 0.028), higher diet quality (p = 0.001), and lower alcohol consumption (p

Aims: Patients with anxiety disorders (AD) have been found to have lower heart rate variability (HRV) than healthy individuals in some studies, but this was inconsistent. Furthermore, the influence of distinct diagnoses, study design, and demographic factors on the results was not comprehensively examined. Methods: We gathered studies comparing HRV in patients with AD and in healthy controls. The parasympathetic activity in the hierarchical order principle was adopted in the main analysis. We adopted the random effects model to calculate the standardized mean difference. Results: Of the 7805 screened studies, 99 were included in the quantitative analysis, with a total of 4897 AD patients and 5559 controls finally entered the meta‐analysis. AD patients had a significantly lower resting‐state HRV for parasympathetic activity compared to control (Hedges' g = −0.3897). For the diagnostic subgroup analysis relative to the controls, resting‐state HRV was significantly lower in post‐traumatic stress disorder, panic disorder, generalized anxiety disorder, and social anxiety disorder patients. HRV reactivity (all reactivity data, data on physiological challenge, and psychological challenge) did not show significant inter‐group differences between AD patients and healthy subjects. Conclusions: The results supported that patients with AD had significantly lower resting‐state HRV than the healthy population, but no alterations were found for HRV reactivity. [ABSTRACT FROM AUTHOR]

Introduction: Female college students (veteran and non-veteran) are exposed to cumulative stressors and trauma that may lead to an imbalanced autonomic nervous system. Yoga has emerged as an efficacious intervention for psychological and physical trauma; however, the therapeutic dose of intervening yoga is unknown. Additionally, the frequency, duration, and type of yoga needed to achieve a therapeutic dose appear to be population specific when applied to trauma victims. The purpose of the study was to examine whether a short-term trauma-informed yoga intervention altered metrics of autonomic tone as assessed by heart rate variability (HRV) in female veteran and non-veteran college students. Methods: Nine female college students (age: 33 years ± 11, veteran, n = 4, non-veteran, n = 5) engaged in trauma-informed yoga once per week for one-hour over a four-week intervention. Repeated measures ANOVA were performed on the HRV variables lnRMSSD, lnHF, lnLF, and LF:HF. Results: Findings indicated no effect of the intervention on HRV as measured by lnRMSSD (p = .116), lnHF (p = .073), lnLF (p = .316), and LF:HF (p = .131). Further, no acute alterations in HRV were observed following a single session of trauma-informed yoga (p > .05). Conclusion: The findings of the study revealed no significant effect of trauma-informed yoga on HRV following a single session or after a four-week yoga intervention. [ABSTRACT FROM AUTHOR]

Psychophysiological research integrating heart rate variability (HRV) has increased during the last two decades, particularly given the fact that HRV is able to index cardiac vagal tone. Cardiac vagal tone, which represents the contribution of the parasympathetic nervous system to cardiac regulation, is acknowledged to be linked with many phenomena relevant for psychophysiological research, including self-regulation at the cognitive, emotional, social, and health levels. The ease of HRV collection and measurement coupled with the fact it is relatively affordable, non-invasive and pain free makes it widely accessible to many researchers. This ease of access should not obscure the difficulty of interpretation of HRV findings that can be easily misconstrued, however, this can be controlled to some extent through correct methodological processes. Standards of measurement were developed two decades ago by a Task Force within HRV research, and recent reviews updated several aspects of the Task Force paper. However, many methodological aspects related to HRV in psychophysiological research have to be considered if one aims to be able to draw sound conclusions, which makes it difficult to interpret findings and to compare results across laboratories. Those methodological issues have mainly been discussed in separate outlets, making difficult to get a grasp on them, and thus this paper aims to address this issue. It will help to provide psychophysiological researchers with recommendations and practical advice concerning experimental designs, data analysis, and data reporting. This will ensure that researchers starting a project with HRV and cardiac vagal tone are well informed regarding methodological considerations in order for their findings to contribute to knowledge advancement in their field.

Background: Psychological improvement after catheter ablation for atrial fibrillation (AF) has been reported, but its mechanism is unclear. Objective: This study aimed to clarify the relationship between cardiac autonomic modification and psychological changes after catheter ablation for paroxysmal AF (PAF). Methods: Thirty-five consecutive patients (60.5 ± 11.9 years; male, n = 24) with PAF treated by catheter ablation were enrolled. Autonomic activity and reactivity to stress and psychological status were measured before (baseline) and at 1 and 3 months after ablation. We assessed autonomic activity and reactivity to stress by measuring heart rate variability (HRV) at rest (Rest), and during (Task) and after (After) the execution of a task and assessed relationships between HRV parameters and psychological changes using the State-Trait Anxiety Inventory (STAI) and Self-Rating Depression Scale (SDS). Results: The STAI state and trait scores significantly decreased at 3 months compared with baseline, whereas SDS scores essentially remained unchanged. The high-frequency (HF) response index (Task/Rest) and HF recovery index (After/Rest) were significantly higher than baseline at 3 months (0.40 [0.29–0.90] vs 1.30 [0.64–2.18], P = .007 for HF response index; 1.13 [0.92–2.19] vs 1.87 [1.19–2.97], P = .049 for HF recovery index). Reductions in STAI scores positively correlated with increments in the HF recovery index in the entire cohort as well as in 5 patients with recurrent AF. Conclusions: Some augmentation of parasympathetic reactivity to stress correlated with reduced anxiety, implying that cardiac autonomic modification plays roles in psychological improvement after catheter ablation for AF.

The main subject of the study of the ecological and medical zoning method is the complex state of the autonomic nervous system (ANS) of the child's organism and the analysis of the processes affecting it. The ANS performs adaptational trophic function - the regulation of the metabolism regarding the conditions of the environment. The analysis of possible ecological problems of the territory and its degree of ecological disturbance can be made due to the received data set on the state of functional health of the children's population of a certain territory and the averaged information on the deviation of the autonomic nervous system. In order to assess the disturbance of the territory, the relative value of the breach of vegetative homeostasis, which is defined as a percentage, is of particular importance. Various organs and systems of the body are known to be associated with certain areas of the skin called acupuncture points. With the appearance of the smallest deviations in the systems of the body and organs, they react at the stage of functional disorders long before the occurrence of organic changes at the expense of meridional bonds. Measuring the electrosurgical resistance in certain acupuncture points you can detect changes in the body still at the stage of functional disorders. For researches, the method of “biogalvanization” of 24 symmetrical representative active functional zones (12 on the arms and 12 on the legs), which reflect the functional activity of the sympathetic and parasympathetic nervous system has been used. This allows to record changes in the activity of sites of the ANS and to obtain systematic data that are subject to further complex analysis. The given method is unique and allows to conduct ecological analysis of the territory with the help of the target group of organisms - a person; method is non-invasive and low-cost, which allows conducting surveys of different age and sex groups and obtaining data with a minimum statistical error.

The time-resolved analysis of heart rate (HR) and heart rate variability (HRV) is crucial for the evaluation of the dynamic changes of autonomic activity under different clinical and behavioral conditions. Standard HRV analysis is performed in the frequency domain because the sympathetic activations tend to increase low-frequency HRV oscillations, while the parasympathetic ones increase high-frequency HRV oscillations. However, a strict separation of HRV in frequency bands may cause biased estimations, especially in the low frequency range. To overcome this limitation, we propose a robust estimator that combines HR and HRV dynamics, based on the correlation of the Poincaré plot descriptors of interbeat intervals from the electrocardiogram. To validate our method, we used electrocardiograms gathered from open databases where standardized paradigms were applied to elicit changes in autonomic activity. Our proposal outperforms the standard spectral approach for the estimation of low- and high-frequency fluctuations in HRV, and its performance is comparable to newer methods. Our method constitutes a valuable, robust, time-resolved, and cost-effective tool for a better understanding of autonomic activity through HR and HRV in healthy state and potentially for pathological conditions.

Background. A game of chess represents a legitimate physical and psychological stress due to its strategic and cognitively demanding nature over a long period of time. This very challenging situation has not been thoroughly explored and, to the best of our knowledge, there is no research report that has concentrated on both heart rate variability and energy expenditure for deeper understanding of chess players' performance. The main aim of the present study was to examine the HRV and EE of chess players before, during and after a competition, as well as the moderate level of running exercise. Methods. The sample comprised 24 (19 men, 5 women; Mage=24.8) volunteer chess players who have been playing chess regularly for at least 5 years. The average National Chess Rating (NCR) of participants was determined as 1526. In addition, a total of ten participants have International Chess Rating (ELO) rating (mean = 1588). We obtained participants' body mass indexes before the experiment took place. Participants' HR and HRV were taken through the chess competition, and running exercises took place in 3 different time periods; before (15 min), during (30 min) and after (15 min). Results. Our results indicated that there was a significant difference on HRV between chess competition and running exercises HRV (RMSSD, SDNN, NN50 and RR) (p=.001). Besides, there was a significant difference on participants' EE between a chess competition and a moderate level of running (p=.001). Conclusions. HRV values determined in chess competition and running exercise are different from each other. Contradictory to our speculative hypothesis, the current results provide that a moderate level of running exercises requires more energy expenditure than a chess game. [ABSTRACT FROM AUTHOR]

Background: Nadishodhana pranayama (NS) has been used extensively for relaxation as well as therapeutics by many practitioners; the physiological effects of NS in this specific ratio have not been studied yet. Hence, the present study aims to evaluate the immediate effect of NS pranayama in the ratio of 1:3:2 with a time line of 6:18:12 s and its role in clinical application. Materials and Methods: Sixty healthy volunteers were recruited for the study. Individuals were randomly allocated into two groups, NS pranayama with antarkumbhaka (Group 1) and breathe awareness (Group 2). For case group, intervention was given for 12 rounds and for the control group, breath awareness was given for 12 rounds and assessed immediately after the practice. Results: In the study group, a significant decrease in mean heart rate (HR) (p < 0.0001) and a significant increase in mean respiratory rate (RR), NN50 (p < 0.0001), RMSSD, and pNN50 (p < 0.0001) after the intervention compared to their prevalues and with that of the control group were noted. Frequency domain analysis of HR variability showed a significant decrease in the pre- and post-values of low-frequency (LF) power (p < 0.0001), very LF, and LF/high-frequency (HF) power (p < 0.0075) and a significant increase in the pre- and post-values of HF power (p < 0.001) after the intervention in the study group. Conclusions: The result concludes that the immediate effect of NS pranayama in the ratio of 1:3:2 brings parasympathetic activity in the study group by decreasing RR and HR. Hence, the NS pranayama with kumbhaka is a better method to increase parasympathetic activity.

Cancer-related fatigue is a common and often long lasting symptom for many breast cancer survivors. Fatigued survivors show evidence of elevated inflammation, but the physiological mechanisms driving inflammatory activity have not been determined. Alterations in the autonomic nervous system, and particularly parasympathetic nervous system activity, are a plausible, yet understudied contributor to cancer-related fatigue. The goal of this study was to replicate one previous study showing an association between lower parasympathetic activity and higher fatigue in breast cancer survivors (Fagundes et al., 2011), and to examine whether inflammation mediates this association. Study participants were drawn from two samples and included 84 women originally diagnosed with early stage breast cancer prior to age 50. Participants completed questionnaires, provided blood samples for determination of interleukin (IL)-6 and C-reactive protein (CRP), and underwent electrocardiography (ECG) assessment for evaluation of resting heart rate variability (HRV), a measure of parasympathetic activity. Results showed that lower HRV was associated with higher fatigue (p

PurposeHeart rate variability (HRV) reflects a healthy autonomic nervous system and is increased with physical training. Methamphetamine dependence (MD) causes autonomic dysfunction and diminished HRV. We compared recently abstinent methamphetamine-dependent participants with age-matched, drug-free controls (DF) and also investigated whether HRV can be improved with exercise training in the methamphetamine-dependent participants.MethodsIn 50 participants (MD = 28; DF = 22), resting heart rate (HR; R-R intervals) was recorded over 5 min while seated using a monitor affixed to a chest strap. Previously reported time domain (SDNN, RMSSD, pNN50) and frequency domain (LFnu, HFnu, LF/HF) parameters of HRV were calculated with customized software. MD were randomized to thrice-weekly exercise training (ME = 14) or equal attention without training (MC = 14) over 8 wk. Groups were compared using paired and unpaired t-tests. Statistical significance was set at P ≤ 0.05.ResultsParticipant characteristics were matched between groups (mean ± SD): age = 33 ± 6 yr; body mass = 82.7 ± 12 kg, body mass index = 26.8 ± 4.1 kg·min. Compared with DF, the MD group had significantly higher resting HR (P < 0.05), LFnu, and LF/HF (P < 0.001) as well as lower SDNN, RMSSD, pNN50, and HFnu (all P < 0.001). At randomization, HRV indices were similar between ME and MC groups. However, after training, the ME group significantly (all P < 0.001) increased SDNN (+14.7 ± 2.0 ms, +34%), RMSSD (+19.6 ± 4.2 ms, +63%), pNN50 (+22.6% ± 2.7%, +173%), HFnu (+14.2 ± 1.9, +60%), and decreased HR (-5.2 ± 1.1 bpm, -7%), LFnu (-9.6 ± 1.5, -16%), and LF/HF (-0.7 ± 0.3, -19%). These measures did not change from baseline in the MC group.ConclusionsHRV, based on several conventional indices, was diminished in recently abstinent, methamphetamine-dependent individuals. Moreover, physical training yielded a marked increase in HRV, representing increased vagal modulation or improved autonomic balance.

Background: Association of physiological recovery with nutrition has scarcely been studied. We investigated whether physiological recovery during sleep relates to eating habits, i.e., eating behaviour and diet quality. Methods: Cross-sectional baseline analysis of psychologically distressed adults with overweight (N = 252) participating in a lifestyle intervention study in three Finnish cities. Recovery measures were based on sleep-time heart rate variability (HRV) measured for 3 consecutive nights. Measures derived from HRV were 1) RMSSD (Root Mean Square of the Successive Differences) indicating the parasympathetic activation of the autonomic nervous system and 2) Stress Balance (SB) indicating the temporal ratio of recovery to stress. Eating behaviour was measured with questionnaires (Intuitive Eating Scale, Three-Factor Eating Questionnaire, Health and Taste Attitude Scales, ecSatter Inventory™). Diet quality was quantified using questionnaires (Index of Diet Quality, Alcohol Use Disorders Identification Test Consumption) and 48-h dietary recall. Results: Participants with best RMSSD reported less intuitive eating (p = 0.019) and less eating for physical rather than emotional reasons (p = 0.010) compared to those with poorest RMSSD; participants with good SB reported less unconditional permission to eat (p = 0.008), higher fibre intake (p = 0.028), higher diet quality (p = 0.001), and lower alcohol consumption (p < 0.001) compared to those with poor SB, although effect sizes were small. In subgroup analyses among participants who reported working regular daytime hours (n = 216), only the associations of SB with diet quality and alcohol consumption remained significant. Conclusions: Better nocturnal recovery showed associations with better diet quality, lower alcohol consumption and possibly lower intuitive eating. In future lifestyle interventions and clinical practice, it is important to acknowledge sleep-time recovery as one possible factor linked with eating habits. Trial registration: ClinicalTrials.gov Identifier NCT01738256, Registered 17 August 2012. [ABSTRACT FROM AUTHOR]

Parkinson’s disease (PD) is a common neurodegenerative disorder classically characterized by symptoms of motor impairment (e.g., tremor and rigidity), but also presenting with important non-motor impairments. There is evidence for the reduced activity of both the parasympathetic and sympathetic limbs of the autonomic nervous system at rest in PD. Moreover, inappropriate autonomic adjustments accompany exercise, which can lead to inadequate hemodynamic responses, the failure to match the metabolic demands of working skeletal muscle and exercise intolerance. The underlying mechanisms remain unclear, but relevant alterations in several discrete central regions (e.g., dorsal motor nucleus of the vagus nerve, intermediolateral cell column) have been identified. Herein, we critically evaluate the clinically significant and complex associations between the autonomic dysfunction, fatigue and exercise capacity in PD.

In healthy humans, fructose-sweetened water consumption increases blood pressure variability (BPV) and decreases spontaneous cardiovagal baroreflex sensitivity (cBRS) and heart rate variability (HRV). However, whether consuming commercially available soft drinks containing high levels of fructose elicits similar responses is unknown. We hypothesized that high-fructose corn syrup (HFCS)-sweetened soft drink consumption increases BPV and decreases cBRS and HRV to a greater extent compared with artificially sweetened (diet) and sucrose-sweetened (sucrose) soft drinks and water. Twelve subjects completed four randomized, double-blinded trials in which they drank 500 mL of water or commercially available soft drinks matched for taste and caffeine content. We continuously measured beat-to-beat blood pressure (photoplethysmography) and R-R interval (ECG) before and 30 min after drink consumption during supine rest for 5 min during spontaneous and paced breathing. BPV was evaluated using standard deviation (SD), average real variability (ARV), and successive variation (SV) methods for systolic and diastolic blood pressure. cBRS was assessed using the sequence method. HRV was evaluated using the root mean square of successive differences (RMSSD) in R-R interval. There were no differences between conditions in the magnitude of change from baseline in SD, ARV, and SV (P = 0.07). There were greater reductions in cBRS during spontaneous breathing in the HFCS (-3 ± 5 ms/mmHg) and sucrose (-3 ± 5 ms/mmHg) trials compared with the water trial (þ1 ± 5 ms/mmHg, P < 0.03). During paced breathing, HFCS evoked greater reductions in RMSSD compared with water (-26 ± 34 vs. þ2 ± 26 ms, P < 0.01). These findings suggest that sugar-sweetened soft drink consumption alters cBRS and HRV but not BPV. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a common neurodegenerative disorder classically characterized by symptoms of motor impairment (e.g., tremor and rigidity), but also presenting with important non-motor impairments. There is evidence for the reduced activity of both the parasympathetic and sympathetic limbs of the autonomic nervous system at rest in PD. Moreover, inappropriate autonomic adjustments accompany exercise, which can lead to inadequate hemodynamic responses, the failure to match the metabolic demands of working skeletal muscle and exercise intolerance. The underlying mechanisms remain unclear, but relevant alterations in several discrete central regions (e.g., dorsal motor nucleus of the vagus nerve, intermediolateral cell column) have been identified. Herein, we critically evaluate the clinically significant and complex associations between the autonomic dysfunction, fatigue and exercise capacity in PD. [ABSTRACT FROM AUTHOR]

New Findings: What is the central question of this study?Do mice submitted to sustained hypoxia present autonomic and respiratory changes similarly to rats?What is the main finding and its importance?Arterial pressure in the normal range, reduced baseline heart rate and tachypnoea were observed in behaving sustained hypoxia mice. Recordings in the in situ preparation of mice submitted to sustained hypoxia show an increase in cervical vagus nerve activity and a simultaneous reduction in thoracic sympathetic nerve activity correlated with changes in the respiratory cycle. Therefore, mice are an important model for studies on the modulation of sympathetic activity to the cardiovascular system and the vagus innervation of the upper airways due to changes in the respiratory network induced by sustained hypoxia. Short‐term sustained hypoxia (SH) in rats induces sympathetic overactivity and hypertension due to changes in sympathetic–respiratory coupling. However, there are no consistent data about the effect of SH on mice due to the different protocols of hypoxia and difficulties associated with the handling of these rodents under different experimental conditions. In situ recordings of autonomic and respiratory nerves in SH mice have not been performed yet. Herein, we evaluated the effects of SH (FiO2 = 0.1 for 24 h) on baseline mean arterial pressure (MAP), heart rate (HR), respiratory frequency (fR) and responses to chemoreflex activation in behaving SH mice. A characterization of changes in cervical vagus (cVN), thoracic sympathetic (tSN), phrenic (PN) and abdominal (AbN) nerves in SH mice using the in situ working heart–brainstem preparation was also performed. SH mice presented normal MAP, significant reduction in baseline HR, increase in baseline fR, as well as increase in the magnitude of bradycardic response to chemoreflex activation. In in situ preparations, SH mice presented a reduction in PN discharge frequency, and increases in the time of expiration and incidence of late‐expiratory bursts in AbN activity. Nerve recordings also indicated a significant increase in cVN activity and a significant reduction in tSN activity during expiration in SH mice. These findings make SH mice an important experimental model for better understanding how changes in the respiratory network may impact on the modulation of vagal control to the upper airways, as well as in the sympathetic activity to the cardiovascular system. [ABSTRACT FROM AUTHOR]

Deficient parasympathetic activity to the heart has been hypothesized to underlie some forms of cardiovascular disease. Consequently, this experiment attempted to induce non- respiratory mediated increases in cardiac parasympathetic activity. Thirty-nine subjects were asked to increase their vagal tone using biofeedback, paced breathing, biofeedback plus paced breathing, or quiet sitting. The cold pressor test was used to examine the relative efficacy of vagal tone increase to mitigate cardiovascular reactivity. Repeated measures ANOVAs and t-tests revealed significant increases in vagal tone for the paced breathing, and biofeedback plus paced breathing groups, relative to controls. However, the quality of these increases could not be tested using the cold pressor test because the test failed to produce homogeneous cardiac reactivity.

The present study was conducted to determine if there were physiological differences between college women who scored high and those who scored low on a scale measuring hostility, anger and aggression during a non-harassing task. Measurements of heart rate, skin conductance (SCL), and respiratory sinus arrhythmia (RSA) were taken during a task designed to elicit anticipatory fear. To measure aggression and its three components, Buss and Perry’s Aggression Questionnaire was used (1992). The results show that there was a significant difference in RSA (F(7,58)=2.225, p=.45, η2= .212). These results suggest that hostile women have low levels of parasympathetic activity prior to the periods of stress, and they are important because they indicate that the physiological differences between hostile and non- hostile women can emerge even with tasks with low levels of provocation.

New Findings: What is the central question of this study?Delayed cardiovascular responses occur following a single bout of remote ischaemic preconditioning (RIPC). Is heart rate variability (HRV), a surrogate marker of cardiac vagal control, able to detect a delayed effect after a single bout of RIPC? Do repeated bouts of RIPC further alter HRV?What is the main finding and its importance?Indices of HRV indicated a shift in sympathovagal balance toward greater parasympathetic activity following 2 weeks of RIPC but not after a single bout of RIPC. Thus, repeated bouts of RIPC were necessary to elicit changes in autonomic function. Remote ischaemic preconditioning (RIPC), induced by brief periods of ischaemia followed by reperfusion, protects against ischaemia–reperfusion injury and improves microvascular function. However, the effect of RIPC on autonomic function remains unclear. We hypothesized that RIPC, administered as a single bout or repeated over a 2‐week period, will increase markers of cardiac vagal control measured by heart rate variability (HRV). Thirty‐two young adults performed a single bout (n = 13), repeated bouts (n = 11), or served as a time control (n = 8). RIPC sessions consisted of four repetitions of 5 min unilateral brachial artery occlusion interspersed by 5 min of reperfusion. For the single bout protocol, resting lead II electrocardiogram (ECG) was collected before and 24, 48, 72 and 168 h post‐RIPC. The repeated bout protocol consisted of three 4‐day periods of RIPC training, each interspersed by a 1‐day break. Similar to time controls, ECG was collected before and 24 h after the last RIPC bout. HRV was analysed by power spectral density and symbolic dynamics using 350‐beat ECG segments. After a single bout of RIPC, no changes in HRV were observed at any time point (P > 0.05). After 2 weeks of repeated RIPC, the percentage of zero‐variation fragments (baseline = 13.1 ± 1.9%, post‐RIPC = 6.9 ± 1.5%, P < 0.05) and the LF/HF ratio decreased (baseline = 1.1 ± 0.2, post‐RIPC = 0.7 ± 0.1, P < 0.01), whereas the percentage of two‐variation fragments increased (baseline = 42.9 ± 3.6%, post‐RIPC = 52.5 ± 3.0%, P < 0.01). These data indicate that repeated RIPC is necessary to elicit changes in sympathovagal balance, specifically resulting in increased vagal and decreased sympathetic activity. [ABSTRACT FROM AUTHOR]

Background: Preeclampsia (PE) is a major obstetric complication that leads to severe maternal and fetal morbidity. Early detection of preeclampsia can reduce the severity of complications and improve clinical outcomes. It is believed that the autonomic nervous system (ANS) is involved in the pathogenesis of PE. We aimed to review the current literature on the prevalence and nature of ANS dysfunction in women with PE and the possible prognostic value of ANS testing in the early detection of PE.Methods: Literature search was performed using Medline (1966–2018), EMBase (1947–2018), Google Scholar (1970–2018), BIOSIS (1926–2018), Web of science (1900–2018); CINAHL (1937–2018); Cochrane Library, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials (CENTRAL) and Cochrane Methodology Register (1999–2018). Additionally, the reference lists of articles included were screened.Results: A total of 26 studies were included in the present review presenting data of 1,854 pregnant women. Among these women, 453 were diagnosed with PE, 93.6% (424/453) of which displayed autonomic dysfunction. ANS function was assessed by cardiovascular reflex tests (n = 9), heart rate variability (n = 11), cardiac baroreflex gain (n = 5), muscle sympathetic nerve activity (MSNA) (n = 3), and biomarkers of sympathetic activity (n = 4). Overall, 21 studies (80.8%) reported at least one of the following abnormalities in ANS function in women diagnosed with PE compared to healthy pregnant control women: reduced parasympathetic activity (n = 16/21, 76%), increased sympathetic activity (n = 12/20, 60%), or reduced baroreflex gain (n = 4/5, 80%). Some of these studies indicated that pressor and orthostatic stress test may be useful in early pregnancy to help estimate the risk of developing PE. However, autonomic function tests seem not to be able to differentiate between mild and severe PE.Conclusions: Current evidence suggests that autonomic dysfunction is highly prevalent in pre-eclamptic women. Among autonomic functions, cardiovascular reflexes appear to be predominantly affected, seen as reduced cardiac parasympathetic activity and elevated cardiac sympathetic activity. The diagnostic value of autonomic testing in the prediction and monitoring of autonomic failure in pre-eclamptic women remains to be determined.

Heart rate (HR) and HR variability (HRV), predictors of over-all organism health, are widely believed to be driven by autonomic input to the sinoatrial node (SAN), with sympathetic input increasing HR and reducing HRV. However, variability in spontaneous beating intervals in isolated SAN tissue and single SAN cells, devoid of autonomic neural input, suggests that clocks intrinsic to SAN cells may also contribute to HR and HRV in vivo. We assessed contributions of both intrinsic and autonomic neuronal input mechanisms of SAN cell function on HR and HRV via in vivo, telemetric EKG recordings. This was done in both wild type (WT) mice, and those in which adenylyl cyclase type 8 (ADCY8), a main driver of intrinsic cAMP-PKA-Ca2+ mediated pacemaker function, was overexpressed exclusively in the heart (TGAC8). We hypothesized that TGAC8 mice would: (1) manifest a more coherent pattern of HRV in vivo, i.e., a reduced HRV driven by mechanisms intrinsic to SAN cells, and less so to modulation by autonomic input and (2) utilize unique adaptations to limit sympathetic input to a heart with high levels of intrinsic cAMP-Ca2+ signaling. Increased adenylyl cyclase (AC) activity in TGAC8 SAN tissue was accompanied by a marked increase in HR and a concurrent marked reduction in HRV, both in the absence or presence of dual autonomic blockade. The marked increase in intrinsic HR and coherence of HRV in TGAC8 mice occurred in the context of: (1) reduced HR and HRV responses to β-adrenergic receptor (β-AR) stimulation; (2) increased transcription of genes and expression of proteins [β-Arrestin, G Protein-Coupled Receptor Kinase 5 (GRK5) and Clathrin Adaptor Protein (Dab2)] that desensitize β-AR signaling within SAN tissue, (3) reduced transcripts or protein levels of enzymes [dopamine beta-hydorxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT)] required for catecholamine production in intrinsic cardiac adrenergic cells, and (4) substantially reduced plasma catecholamine levels. Thus, mechanisms driven by cAMP-PKA-Ca2+ signaling intrinsic to SAN cells underlie the marked coherence of TGAC8 mice HRV. Adaptations to limit additional activation of AC signaling, via decreased neuronal sympathetic input, are utilized to ensure the hearts survival and prevent Ca2+ overload.

Purpose: Sweat-induced fluid loss during prolonged exercise-heat stress can compromise cardiovascular and thermoregulatory function, although its effects on cardiac autonomic modulation remain unclear. We therefore examined heart rate variability (HRV) and recovery (HRRec), as surrogates of cardiac autonomic modulation, during and after prolonged exercise in the heat with and without fluid replacement. Methods: Eleven young and healthy men performed 90 min of semi-recumbent cycling in dry heat (40 ° C; 20% relative humidity) at a fixed rate of metabolic heat production (600 W; ~46% V˙O2peak) followed by 40-min resting recovery without fluid replacement (No-FR; ~3.4% reduction in body mass). On a separate day, participants completed the same protocol with fluid replacement (FR; 500–700 mL timed boluses) to offset sweat losses. Esophageal temperature and ECG were recorded throughout, with measurements analyzed over 10-min averaged epochs during baseline, each 30-min interval during exercise and 20-min interval during recovery. Results: Esophageal temperature and heart rate were elevated in No-FR relative to FR throughout exercise (all P ≤ 0.02). The HRV indices reflecting vagal influence of heart rate including the cardiac vagal index (CVI = log10[16 × SD1 × SD2]) and root-mean-square of successive differences were attenuated throughout exercise relative to baseline in both conditions (all P < 0.05), with the magnitude of the reduction greater in the No-FR condition (all P < 0.05). Further, sample entropy was reduced throughout all time points measured during exercise in the No-FR relative to FR condition (all P ≤ 0.03). Conclusions: Our unique observations indicate that while prolonged exercise heat stress attenuates the vagal influence and complexity of cardiac rhythms, that reduction is further exacerbated by fluid loss, highlighting the importance of fluid replacement in such conditions. [ABSTRACT FROM AUTHOR]