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Background: Obesity has been identified as a global epidemic that is associated with numerous comorbidities such as type 2 diabetes, hypertension, cancer, cardiovascular disease. We have investigated the effects of Watsu® therapy and Immersion on HRV parameters of obese male subjects. Methods and Results: Volunteer 34 obese subjects with BMI above 30 without any other chronic health issues were included (age, 18.30 ± 0.31, height, 166.02 ± 29.60, BMI, 36.54 ± 5.96). Randomized controlled trial was conducted with Watsu and Immersion protocols whereas control group received no therapy in water or on land for 12 weeks. A baseline HRV was recorded 5 minutes in four different circumstances. Polar H7 heart rate sensor and digital standardized HRV signal processing software were used to record the R-R intervals in millisecond. The repeated measures were used to compare the conditions between the therapies. The HRV analyses were performed using three-way Mixed ANOVA. Multiple comparisons were done with a Bonferroni adjustment of the alpha level (0.05). The collective results of HF showed significant negative effect (13.01 ± 1.36, 9.99 ± 1.11) and HF laying supine value (20.62 ± 2.22) was the highest (p<0.05). Conclusion: A significant inverse correlation was found between HRV values and both therapeutic interventions. Counterintuitively, 12-week of watsu and immersion therapies decreased LF and HF.

Regular physical activity is important for cardiovascular health. However, high-volume endurance exercise has been associated with increased number of electrocardiogram (ECG) abnormalities, including disturbances in cardiac rhythm (arrhythmias) and abnormalities in ECG pattern. The aim of this study was to assess if heart rate variability (HRV) is associated with ECG abnormalities. Fifteen participants with previous cycling experience completed a 21-day high-volume endurance exercise cycle over 3,515 km. Participants wore a 5-lead Holter monitor for 24 h pre- and post-exercise, which was used to quantify ECG abnormalities and export sinus R-to-R intervals (NN) used to calculate HRV characteristics. As noise is prevalent in 24-h HRV recordings, both 24-h and heart rate collected during stable periods of time (i.e., deep sleep) were examined. Participants experienced significantly more arrhythmias post high-volume endurance exercise (median = 35) compared to pre (median = 12; p = 0.041). All 24-h and deep sleep HRV outcomes were not different pre-to-post high-volume endurance exercise (p > 0.05). Strong and significant associations with arrhythmia number post-exercise were found for total arrhythmia (total arrhythmia number pre-exercise, ρ = 0.79; age, ρ = 0.73), supraventricular arrhythmia (supraventricular arrhythmia number pre-exercise: ρ = 0.74; age: ρ = 0.66), and ventricular arrhythmia (age: ρ = 0.54). As a result, age and arrhythmia number pre-exercise were controlled for in hierarchical regression, which revealed that only deep sleep derived low frequency to high frequency (LF/HF) ratio post high-volume endurance exercise predicted post total arrhythmia number (B = 0.63, R2Δ = 34%, p = 0.013) and supraventricular arrhythmia number (B = 0.77, R2Δ = 69%, p < 0.001). In this study of recreationally active people, only deep sleep derived LF/HF ratio was associated with more total and supraventricular arrhythmias after high-volume endurance exercise. This finding suggests that measurement of sympathovagal balance during deep sleep might be useful to monitor arrhythmia risk after prolonged high-volume endurance exercise performance.

Background : Transcutaneous electrical acupoint stimulation (TEAS) improves autonomic balance and reduces oxidative stress in subjects with chronic diseases, that decreases the risk of low-grade chronic inflammatory diseases, including cardiovascular diseases. However, these beneficial effects have never been demonstrated in healthy subjects. Objectives: To evaluate the acute effects of TEAS on autonomic balance and oxidative stress of healthy subjects. Methods : A randomized clinical trial was conducted with male healthy subjects (18-30 years old), randomly allocated to control (no intervention; n = 14), placebo (placebo intervention; n = 14) and TEAS group (at PC5 and PC6 acupoints; n = 13). The protocol consisted of accommodation (20 min), intervention (40 min), and recovery (30 min) periods. The acute effects of TEAS on hemodynamics were studied through measurements of heart rate, blood pressure and double product; on the autonomic nervous system by assessing heart rate variability; and on oxidative stress by quantifying reactive oxygen species in saliva samples, collected at the end of each period. Results : TEAS increased heart rate and double-product compared to control and placebo groups (p < 0.01). Moreover, TEAS increased sympathetic and reduced parasympathetic tonus, increasing the sympathovagal balance compared to the control and placebo groups. However, TEAS exerted no effect on oxidative stress in saliva samples. Conclusion : In healthy subjects, TEAS at PC5 and PC6 acupoints acutely improved autonomic balance, increasing sympathetic and reducing parasympathetic tonus, reflecting little improvement on hemodynamic responses. Whether it could be used as a cardioprotective strategy remains uncertain since it exerted no effect on oxidative stress.

We briefly review the evidence for distinct neuroanatomical substrates that underlie interoception in humans, and we explain how they substantialize feelings from the body (in the insular cortex) that are conjoined with homeostatic motivations that guide adaptive behaviours (in the cingulate cortex). This hierarchical sensorimotor architecture coincides with the limbic cortical architecture that underlies emotions, and thus we regard interoceptive feelings and their conjoint motivations as homeostatic emotions We describe how bivalent feelings, emotions and sympathovagal balance can be organized and regulated efficiently in the bicameral forebrain as asymmetric positive/negative, approach/avoidance and parasympathetic/sympathetic components. We provide original evidence supporting this organization from studies of cardiorespiratory vagal activity in monkeys and functional imaging studies in healthy humans showing activation modulated by paced breathing and passively viewed emotional images. The neuroanatomical architecture of interoception provides deep insight into the functional organization of all emotional feelings and behaviours in humans.This article is part of the themed issue 'Interoception beyond homeostasis: affect, cognition and mental health'.

BACKGROUND: Non-ordinary states of consciousness induced by psychedelics can be accompanied by so-called peak experiences, characterized at the emotional level by their intensity and positive valence. These experiences are strong predictors of positive outcomes following psychedelic-assisted therapy, and it is therefore important to better understand their biology. Despite growing evidence that the autonomic nervous system (ANS) plays an important role in mediating emotional experiences, its involvement in the psychedelic experience is poorly understood. The aim of this study was to investigate to what extent changes in the relative influence of the sympathetic (SNS) and parasympathetic nervous systems (PNS) over cardiac activity may reflect the subjective experience induced by the short-acting psychedelic N,N-Dimethyltryptamine (DMT). METHODS: We derived measures of SNS and PNS activity from the electrocardiograms of 17 participants (11 males, mean age = 33.8 years, SD = 8.3) while they received either DMT or placebo. RESULTS: Results show that the joint influence of SNS and PNS (sympathovagal coactivation) over cardiac activity was positively related to participants ratings of Spiritual Experience and Insightfulness during the DMT experience, while also being related to improved well-being scores 2 weeks after the session. In addition, we found that the state of balance between the two ANS branches (sympathovagal balance) before DMT injection predicted scores of Insightfulness during the DMT experience, as well as subsequent sympathovagal coactivation. CONCLUSION: These findings demonstrate the involvement of the ANS in psychedelic-induced peak experiences and may pave the way to the development of biofeedback-based tools to enhance psychedelic therapy.

QT interval (QT) variability analysis provides pathophysiological and prognostic information utilized in cardiac and non-cardiac diseases, complementary to those obtained from the analysis of heart period (HP) variability. An increased QT variability has been associated to a higher risk for cardiac events and poorest prognosis. Autonomic cardiovascular adaptation to internal and external challenges, such those occurring in athletes exposed to high levels of physical stress and in ageing could also be deepen by analyzing QT variability, searching for early prognostic signatures. The aim of the study was to analyze the QT variability and cardiac control complexity in a group of middle-aged half-marathon runners at baseline (B) and at a 10-year follow-up (FU). We found that the overall QT variability decreased at FU, despite the inescapable increase in age (52.3 ± 8.0 years at FU). This change was accompanied by an increase of the HP variability complexity without changes of the QT variability complexity. Of notice, over the years, the group of athletes maintained their regular physical activity by switching to a moderate intensity rather than strenuous. In conclusion, regular and moderate exercise over the years was beneficial for this group of athletes, as reflected by the decreased overall QT variability that is known to be associated to lower cardiovascular risk. The concomitant enhanced cardiac control complexity also suggests a trend opposite to what usually occurs with ageing, resulting in a more flexible cardiac control, typical of younger people.

BACKGROUND: Heart rate variability (HRV) is the variation in the time intervals between continuous heartbeats also called interbeat intervals to give information related to the heart, blood pressure, gaseous exchange, and sympathetic and parasympathetic balance. Abnormalities in the conduction of the cardiac system alter the measurements of heart rate variability and lead to alteration in autonomic function with a higher risk of mortality. So, our objective includes the assessment of sympathovagal balance in AFLD and NAFLD patients. MATERIALS AND METHODS: The study included 78 alcoholic and 54 nonalcoholic fatty liver patients. A room temperature of 23°C with 25–35% humidity will be maintained in a recording room. Basal supine heart rate and BP will be recorded by the oscillometric method using an automated blood pressure monitor Omron MX3, India. Lead II ECG will be recorded for the next 5 minutes in total resting condition for short-term HRV analysis. Short-term HRV indices including time domain and frequency domain were recorded from each patient. Under time domain, SDNN, RMSSD, and average RR were noted. Under frequency domain, LF, HF, VLF, LF (nu), HF (nu), and LF/HF were calculated. The data were collected by using a 16-bit, power lab 8/30 data acquisition system (New South Wales, Australia) with acknowledge 3.8.2 software. Inferential analyses such as independent t-tests and Mann–Whitney tests were used to compare NAFLD and AFLD patient groups. Carl Pearson correlation analysis was performed to obtain a relationship between variables. RESULTS: SDNN in (ms) which represents the overall HRV found to be decreased in both alcoholic (32.84 ± 79.08) and nonalcoholic fatty liver disease (22.04 ± 13.85) compared to the normal range (50 ± 16)) from 27 studies. The value of RMSSD in (ms) was decreased in both alcoholic (17.00 ± 12.48) and nonalcoholic fatty liver disease patients (14.00 ± 9.44) with the normal range of (42 ± 15) from 15 studies. Pearson correlation analysis showed the age of AFLD patients significantly and positively correlated with average RR. Pearson correlation analysis for the age of NAFLD patients was significantly and positively correlated with the average RR, HF, SDNN, RMSSD, and LF. CONCLUSION: Altered autonomic activity was noted in both alcoholic and nonalcoholic fatty liver disease patients. An early prognosis of fatty liver is very necessary to prevent the disease progress into later fatal life-threatening stages.

Background Heart rate variability (HRV) is one piece among a complex network of adaptations existent in athletes that help them gain a better understanding of their own physiology. Sympathovagal balance is one of the spectral components of HRV analysis and is used to assess the frequently changing oscillations of a healthy heart, which can help in gauging the response of cardiac function towards physiological stress during exercise. This index is extensively used in appraising cardiac autonomic modulation. An evaluation of body composition in athletes has become a critical consideration when tracking HRV, as it helps practitioners understand the role of the autonomic nervous system (ANS) in obesity. The body shape index (BSI), which is based on waist circumference (WC), is an anthropometric parameter with decent predictive ability when measuring centripetal obesity. In this regard, the current study is an attempt to unravel the relationship between BSI and sympathovagal balance during exercise performed on two different instruments (treadmill and ergometer) by elite and amateur athletes. Methods It was an observational case-control study that included 30 elite and 120 amateur athletes. Symptom-limited exercise testing was performed by athletes on a motorized treadmill and ergometer in the sports physiology laboratory of a rural medical college in central India. Different anthropometric parameters like BSI and body surface area (BSA) were also recorded. Short-term HRV extracted from electrocardiogram (ECG) recordings was obtained using the Power Lab system and HRV analysis by LabChart software. Results The sympathovagal ratio, i.e., ratio of low frequency (LF) to high frequency (HF) in elite and amateur male populations showed a higher value than that in females, indicating a dominant sympathetic response in the males. There was a significant (p=0.042) positive correlation (r=0.24) between BSI and LF/HF Ratio in amateur females during treadmill exercise, whereas a significant (p=0.049) negative correlation (r=-0.27) was obtained in amateur males during ergometer exercise. Hence, increased weight and BSI were found to be associated with high sympathetic dominance, indicating a sympathovagal imbalance. Conclusion We attempted to explore the interaction between BSI and LF/HF during exercise performed on two different instruments (treadmill and ergometer) by elite and amateur athletes, which can help in testing the response of cardiac function to stress experienced during exercise. The study's uniqueness stems from discovering the relationship between BSI and HRV and how this relationship impacts sports performance. BSI measurement in athletes, both elite and amateur, allows for the assessment and forecasting of potential autonomic activity under exercise-induced stress by linking HRV with BSI., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Kothari et al.)

Background: Transcutaneous electrical acupoint stimulation (TEAS) improves autonomic balance and reduces oxidative stress in subjects with chronic diseases, that decreases the risk of low-grade chronic inflammatory diseases, including cardiovascular diseases. However, these beneficial effects have never been demonstrated in healthy subjects. Objectives: To evaluate the acute effects of TEAS on autonomic balance and oxidative stress of healthy subjects. Methods: A randomized clinical trial was conducted with male healthy subjects (18-30 years old), randomly allocated to control (no intervention; n = 14), placebo (placebo intervention; n = 14) and TEAS group (at PC5 and PC6 acupoints; n = 13). The protocol consisted of accommodation (20 min), intervention (40 min), and recovery (30 min) periods. The acute effects of TEAS on hemodynamics were studied through measurements of heart rate, blood pressure and double product; on the autonomic nervous system by assessing heart rate variability; and on oxidative stress by quantifying reactive oxygen species in saliva samples, collected at the end of each period. Results: TEAS increased heart rate and double-product compared to control and placebo groups (p < 0.01). Moreover, TEAS increased sympathetic and reduced parasympathetic tonus, increasing the sympathovagal balance compared to the control and placebo groups. However, TEAS exerted no effect on oxidative stress in saliva samples. Conclusion: In healthy subjects, TEAS at PC5 and PC6 acupoints acutely improved autonomic balance, increasing sympathetic and reducing parasympathetic tonus, reflecting little improvement on hemodynamic responses. Whether it could be used as a cardioprotective strategy remains uncertain since it exerted no effect on oxidative stress. [ABSTRACT FROM AUTHOR]

Abstract Studies have shown improvement of the cardiac autonomic balance in post-bariatric patients. Most of these studies included patients using drugs interfering in the autonomic nervous system. This study assessed the time course of changes in the sympathovagal balance after bariatric surgery (Roux-en-Y gastric bypass) in 26 women free from drugs. A 10-min electrocardiographic recording was obtained at baseline and at 3 and 6 months after surgery. Temporal and spectral domains of heart rate variability were analysed. The time domain components of cardiac vagal modulation increased progressively after surgery. In the frequency domain, high frequency power increased from 24.9 at baseline (18.0 to 46.3) to 44.5 at 3 months (23.4 to 65.6), and 54.1 at 6 months after surgery (37.6 to 64.0) (median and IQR in normalized units). Low frequency spectral power decreased from 56.2 at baseline (39.6 to 74.4) to 36.8 at 6 months after surgery (24.9 to 53.9) (P= 0.036). Low frequency/high frequency ratio decreased from 2.3 at baseline (1.0 to 4.2) to 0.8 at 6 months after surgery (0.4 to 1.3) (P= 0.038). Progressive shift towards predominance of vagal tonus was detected in the follow-up. Most of the patients recovered low frequency/high frequency at 6 months after surgery.

The low incidence of cardiovascular diseases, including hypertension, in premenopausal women has led to the conclusion that ovarian hormones may have a protective effect on the cardiovascular system. We evaluated the effects of ovariectomy and/or estradiol on sympathovagal balance and heart rate variability (HRV) in female spontaneously hypertensive rats (SHR) with tachycardia and compared them to Wistar rats (12 weeks old; N = 8-12). Ovariectomy (OVX) and/or estradiol (10 µg/kg) did not affect basal arterial pressure in either rat strain, but estradiol increased basal heart rate (HR) in OVX SHR (454 ± 18 vs 377 ± 9 bpm). HR changes elicited by methylatropine and propranolol were used to evaluate the sympathovagal balance. Ovariectomy did not affect the cardiac sympathovagal balance of any group, while estradiol increased sympathetic tone in OVX SHR (120 ± 8 vs 56 ± 10 bpm) and sham-operated Wistar rats (57 ± 7 vs 28 ± 4 bpm), and decreased the parasympathetic tone only in OVX SHR (26 ± 7 vs 37 ± 5 bpm). HRV was studied in the frequency domain (Fast Fourier Transformation). Spectra of HR series were examined at low frequency (LF: 0.2-0.75 Hz) and high frequency (HF: 0.75-3 Hz) bands. The power of LF, as well as the LF/HF ratio, was not affected by ovariectomy, but estradiol increased both LF (29 ± 4 vs 18 ± 3 nu in Wistar sham-operated, 26 ± 5 vs 15 ± 3 nu in Wistar OVX, 50 ± 3 vs 38 ± 4 nu in SHR sham-operated, and 51 ± 3 vs 42 ± 3 nu in SHR OVX) and LF/HF (0.48 ± 0.08 vs 0.23 ± 0.03 nu in Wistar sham-operated, 0.41 ± 0.14 vs 0.19 ± 0.05 nu in Wistar OVX, 0.98 ± 0.11 vs 0.63 ± 0.11 nu in SHR sham-operated, and 1.10 ± 0.11 vs 0.78 ± 0.1 nu in SHR OVX). Thus, we suggest that ovariectomy did not affect the cardiac sympathovagal balance of SHR or Wistar rats, while estradiol increased the sympathetic modulation of HR.

Background: Postural tachycardia syndrome (POTS) is a common form of chronic orthostatic intolerance. The remarkable increase in heart rate (HR) upon standing is the hallmark of this syndrome. Treatment of POTS patients is challenging and includes drugs that slow the HR. Ivabradine is a selective If channel blocker designed to slow the HR, as an anti-anginal agent. In view of its ability to slow the HR, we posited that ivabradine may be an ideal medication for treating POTS patients. This report provides the results of an investigation in which we studied ivabradine’s effect on the hemodynamics and sympathovagal balance in POTS patients. Methods: An open-label trial, without a placebo control, was performed in eight patients with POTS of two years’ standing. Characterization of symptoms, hemodynamics, autonomic function tests, and HR and blood pressure (BP) variability were determined while patients were in a supine position and during a 20-minute head-up tilt before and after a single oral dose of 7.5 mg ivabradine. Results: Ivabradine slowed the HR of POTS patients at rest by 4±1 bpm (P

Discovery of therapeutic avenues to provide the benefits of exercise to patients with enforced sedentary behavior patterns would be of transformative importance to health care. Work in model organisms has demonstrated that benefits of exercise can be provided to stationary animals by daily intermittent stimulation of adrenergic signaling. Here, we examine as a proof of principle whether exposure of human participants to virtual reality (VR) simulation of exercise can alter sympathovagal balance in stationary humans. In this study, 24 participants performed 15 minutes of cycling exercise at standardized resistance, then repeated the exercise with a virtual reality helmet that provided an immersive environment. On a separate day, they each controlled a virtual environment for 15 minutes to simulate exercise without actual cycling exercise. Response to each treatment was assessed by measuring heart rate (HR), norepinephrine, and heart rate variability, and each participant's response to virtual exercise was compared internally to his/her response to the actual cycling. We found that neither post-exercise norepinephrine nor post-exercise HR was significantly increased by VR simulation. However, heart rate variability measured during virtual exercise was comparable to actual cycling in participants that engaged in moderate exercise, but not in those that engaged in high-intensity exercise. These findings suggest that virtual exercise has the potential to mimic some effects of moderate exercise. Further work will be needed to examine the longitudinal effects of chronic exposure to VR-simulated exercise.

Introduction : Pain hypersensitivity, abnormal motility and autonomic dysfunction contribute to functional symptoms of inflammatory bowel disease (IBD). Material and methods : The aim of this study was to assess: nociceptive thresholds for mechanical allodynia (MA) and thermal hyperalgesia (TH), intestinal motility (distal colonic transit and emptying), and cardiac autonomic neuropathy (indices of heart rate variability – HRV) in male Wistar rats with experimental trinitrobenzene sulfonic acid (TNBS) induced colitis. To identify a potential vagal contribution the bilateral subdiaphragmatic vagotomy (SDV) was performed. Results: Experimental colitis resulted in a significant decrease in pain threshold (MA 23.60 ±2.12, p < 0.001, TH 8.51 ±1.49, p < 0.001), reduced expulsion time (6.2 ±3.5, p < 0,01) and increase in the sympathetic autonomic activity (LFnu 32.54 ±21.16, p < 0.03). The animals with diminished vagal integrity presented with reduced gastrointestinal motility (39.8 ±25.1, p < 0.01) and a decrease in the parasympathetic high-frequency domain of HRV (HFnu 55.37 ±22.80, p < 0.002). The vagotomized rats with colitis showed the strongest nociceptive response (MA 22.46 ±3.02, p < 0.004; TH 7.99 ±1.12, p < 0.003) as well as significant changes in sympatho-vagal balance on HRV testing (LFnu 28.25 ±14.66, p < 0.04; HFnu 71.34 ±14.55, p < 0.04). Conclusions : The relationship between the cardiovascular and gastrointestinal system is modulated by neural, hormonal and inflammatory factors. This leads to dysregulation of the brain-gut interactions in the course of IBD. Sensitization and visceral-somatic convergence trigger pain hypersensitivity and autonomic sympathovagal imbalance. While integral vagal innervation impacts analgesic mechanisms via modulation of the immune response, SDV raises sympathetic activity and induces excessive hyperalgesia.