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Background: Changes in cardiovascular health indicators during childhood and adolescence can lead to cardiovascular diseases in adulthood. Excess body fat is one of the main factors for cardiovascular diseases. Thus, new strategies for the practice of physical activity with this population are needed to prevent and/or reverse this situation. Aim: To analyze the effects of 16 weeks of Muay Thai practice on heart rate variability, blood pressure, and resting heart rate in children and adolescents with overweight/obesity. Methods: The sample is composed of 30 children and adolescents of both sexes (17 male and 13 female) aged 12.50 ± 2.12 years. The participants were divided into Muay Thai (n = 17) and control (n = 13). Systolic and diastolic blood pressure and heart rate were measured using an automatic oscillometric device. Heart rate variability was assessed by a frequency meter and was analyzed considering the time domain indices, frequency, and the Poincaré plot. The outcomes were evaluated before (initial time) and after 16 weeks. The Muay Thai group, performed an intervention with Muay Thai training for 16 weeks (three times a week on non-consecutive days). Each training session lasted 90 min and the intensity was maintained from moderate to high using the perceived exertion scale. Results: The Muay Thai group demonstrated lower heart rate values than the control group at the pre-test (p = 0.040). In addition, the Muay Thai group decreased the heart rate in post-test when compared to the pre-test (p < 0.001). Conclusion: 16 weeks of Muay Thai shows a tendency to reduce resting heart rate in children and adolescents with overweight/obesity. [ABSTRACT FROM AUTHOR]

Simple Summary: The impact of a fasting intervention on cardiometabolic health is a noteworthy topic in the scientific community, whereby the coherences of a fasting intervention and autonomic cardiac responses is a topic that is scarcely analyzed. Therefore, the aim of this study is to scientifically investigate the influence of different fasting interventions on cardiometabolic health, i.e., autonomic cardiac response. Twenty-seven individuals (male 16, female 11, aged 26.3 ± 3.8 years) participated and completed this study with a controlled run-in period and were included for analyses. Following the controlled run-in period, participants were randomized into three different fasting groups: (I) alternate day fasting (24/24 h of fasting/feasting; n = 8); (II) the 16/8 fasting cohort (16/8 h of fasting/feasting, n = 11) and (III) the 20/4 fasting method, including 20/4 h of fasting/feasting (n = 8). An analysis of baseline electrocardiogram parameters and heart rate variability parameters following different fasting interventions demonstrated the safety of these interventions without impacting on heart rate variability parameters during Schellong-1 testing, and demonstrated comparable preserved autonomic responses independently of the fasting intervention. In conclusion, different fasting protocols showed comparable cardiac autonomic responses, determined by electrocardiogram and heart rate variability measurements. The impact of a fasting intervention on electrocardiographic (ECG) time intervals and heart rate variability (HRV) is a focus that is scarcely analyzed. The main focus of these secondary outcome data was to describe the impact of a different fasting intervention on ECG and HRV analyses. Twenty-seven healthy individuals participated in this study (11 females, aged 26.3 ± 3.8 years, BMI 24.7 ± 3.4 kg/m2), including a pre-intervention controlled run-in period. Participants were randomized to one of the three fasting cohorts: (I) alternate day fasting (ADF, n = 8), (II) 16/8 fasting (16/8 h of fasting/feasting, n = 11) and (III) 20/4 fasting (20/4 h of fasting/feasting, n = 8). An analysis of baseline ECG parameters and HRV parameters following different fasting interventions demonstrated the safety of these interventions without impacting on heart rate variability parameters during Schellong-1 testing, and revealed comparable preserved autonomic cardiac modulation (ACM) independently of the fasting intervention. In conclusion, different short-term fasting interventions demonstrated no safety ECG-based concerns and showed comparable ACM based on ECG and HRV assessments. Finally, our research topic might strengthen the scientific knowledge of intermittent fasting strategies and indicate potential clinically preventive approaches with respect to occurring metabolic disease and obesity in healthy young subjects. [ABSTRACT FROM AUTHOR]

Cardiovascular regulatory mechanisms that fail to compensate for ultrafiltration and cause hypovolemia during hemodialysis (HD) are not completely understood. This includes the interaction between the autonomic nervous system and the biochemistry that regulates blood pressure and modulates cardiac activity and vascular tone in response to hypovolemia in patients treated with HD. The objective was to evaluate the association of spectral indices of heart rate variability (HRV) with serum levels of angiotensin II, angiotensin 1–7, nitric oxide and total antioxidant capacity during HD. Electrocardiographic records were obtained from 20 patients during HD (3 h), from which HRV data and spectral power data in the very-low-frequency (VLF), low-frequency (LF) and high-frequency (HF) bands were generated. Three blood samples per patient were collected during HD (0.0, 1.5, 3.0 h) to determine the levels of biomarkers involved in the pressor response during HD. Angiotensin II had a positive correlation with VLF (r = 0.390) and with LF/HF (r = 0.359) and a negative correlation with LF (r = −0.262) and HF (r = −0.383). There were no significant correlations between HRV and the other biomarkers. These results suggest that during HD, VLF could reflect the serum levels of angiotensin II, which may be associated with the autonomic response to HD. [ABSTRACT FROM AUTHOR]

The impact of a fasting intervention on electrocardiographic (ECG) time intervals and heart rate variability (HRV) is a focus that is scarcely analyzed. The main focus of these secondary outcome data was to describe the impact of a different fasting intervention on ECG and HRV analyses. Twenty-seven healthy individuals participated in this study (11 females, aged 26.3 ± 3.8 years, BMI 24.7 ± 3.4 kg/m2), including a pre-intervention controlled run-in period. Participants were randomized to one of the three fasting cohorts: (I) alternate day fasting (ADF, n = 8), (II) 16/8 fasting (16/8 h of fasting/feasting, n = 11) and (III) 20/4 fasting (20/4 h of fasting/feasting, n = 8). An analysis of baseline ECG parameters and HRV parameters following different fasting interventions demonstrated the safety of these interventions without impacting on heart rate variability parameters during Schellong-1 testing, and revealed comparable preserved autonomic cardiac modulation (ACM) independently of the fasting intervention. In conclusion, different short-term fasting interventions demonstrated no safety ECG-based concerns and showed comparable ACM based on ECG and HRV assessments. Finally, our research topic might strengthen the scientific knowledge of intermittent fasting strategies and indicate potential clinically preventive approaches with respect to occurring metabolic disease and obesity in healthy young subjects.

Mindfulness-based interventions (MBIs) have been used widely as a useful tool for the alleviation of various stress-related symptoms. However, the effects of MBIs on stress-related physiological activity have not yet been ascertained. MBIs primarily consist of focused-attention (FA) and open-monitoring (OM) meditation. Since differing effects of FA and OM meditation on brain activities and cognitive tasks have been mentioned, we hypothesized that FA and OM meditation have also differing effects on stress-related physiological activity. In this study, we examined the effects of FA and OM meditation on autonomic cardiac modulation and cortisol secretion. Forty-one healthy adults (aged 20–46 years) who were meditation novices experienced 30-min FA and OM meditation tasks by listening to instructions. During resting- and meditation-states, electrocardiogram transducers were attached to participants to measure the R-R interval, which were used to evaluate heart rate (HR) and perform heart rate variability (HRV) analyses. Saliva samples were obtained from participants pre- and post-meditation to measure salivary cortisol levels. Results showed that FA meditation induced a decrease in HR and an increase in the root mean square of successive differences (rMSDD). In contrast, OM meditation induced an increase in the standard deviation of the normal-to-normal interval (SDNN) to rMSSD ratio (SDNN/rMSSD) and a decrease in salivary cortisol levels. These results suggest that FA meditation elevates physiological relaxation, whereas OM meditation elevates physiological arousal and reduces stress.

ObjectiveThe aim of this study was to assess age-related changes in cardiac autonomic modulation and heart rate variability (HRV) and their association with spontaneous and pharmacologically induced vulnerability to cardiac arrhythmias, to verify the translational relevance of mouse models for further in-depth evaluation of the link between autonomic changes and increased arrhythmic risk with advancing age.MethodsHeart rate (HR) and time- and frequency-domain indexes of HRV were calculated from Electrocardiogram (ECG) recordings in two groups of conscious mice of different ages (4 and 19 months old) (i) during daily undisturbed conditions, (ii) following peripheral β-adrenergic (atenolol), muscarinic (methylscopolamine), and β-adrenergic + muscarinic blockades, and (iii) following β-adrenergic (isoprenaline) stimulation. Vulnerability to arrhythmias was evaluated during daily undisturbed conditions and following β-adrenergic stimulation.ResultsHRV analysis and HR responses to autonomic blockades revealed that 19-month-old mice had a lower vagal modulation of cardiac function compared with 4-month-old mice. This age-related autonomic effect was not reflected in changes in HR, since intrinsic HR was lower in 19-month-old compared with 4-month-old mice. Both time- and frequency-domain HRV indexes were reduced following muscarinic, but not β-adrenergic blockade in younger mice, and to a lesser extent in older mice, suggesting that HRV is largely modulated by vagal tone in mice. Finally, 19-month-old mice showed a larger vulnerability to both spontaneous and isoprenaline-induced arrhythmias.ConclusionThe present study combines HRV analysis and selective pharmacological autonomic blockades to document an age-related impairment in cardiac vagal modulation in mice which is consistent with the human condition. Given their short life span, mice could be further exploited as an aged model for studying the trajectory of vagal decline with advancing age using HRV measures, and the mechanisms underlying its association with proarrhythmic remodeling of the senescent heart.

Mindfulness-based interventions (MBIs) have been used widely as a useful tool for the alleviation of various stress-related symptoms. However, the effects of MBIs on stress-related physiological activity have not yet been ascertained. MBIs primarily consist of focused-attention (FA) and open-monitoring (OM) meditation. Since differing effects of FA and OM meditation on brain activities and cognitive tasks have been mentioned, we hypothesized that FA and OM meditation have also differing effects on stress-related physiological activity. In this study, we examined the effects of FA and OM meditation on autonomic cardiac modulation and cortisol secretion. Forty-one healthy adults (aged 20–46 years) who were meditation novices experienced 30-min FA and OM meditation tasks by listening to instructions. During resting- and meditation-states, electrocardiogram transducers were attached to participants to measure the R-R interval, which were used to evaluate heart rate (HR) and perform heart rate variability (HRV) analyses. Saliva samples were obtained from participants pre- and post-meditation to measure salivary cortisol levels. Results showed that FA meditation induced a decrease in HR and an increase in the root mean square of successive differences (rMSDD). In contrast, OM meditation induced an increase in the standard deviation of the normal-to-normal interval (SDNN) to rMSSD ratio (SDNN/rMSSD) and a decrease in salivary cortisol levels. These results suggest that FA meditation elevates physiological relaxation, whereas OM meditation elevates physiological arousal and reduces stress. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to assess age-related changes in cardiac autonomic modulation and heart rate variability (HRV) and their association with spontaneous and pharmacologically induced vulnerability to cardiac arrhythmias, to verify the translational relevance of mouse models for further in-depth evaluation of the link between autonomic changes and increased arrhythmic risk with advancing age. Methods: Heart rate (HR) and time- and frequency-domain indexes of HRV were calculated from Electrocardiogram (ECG) recordings in two groups of conscious mice of different ages (4 and 19 months old) (i) during daily undisturbed conditions, (ii) following peripheral β-adrenergic (atenolol), muscarinic (methylscopolamine), and β-adrenergic + muscarinic blockades, and (iii) following β-adrenergic (isoprenaline) stimulation. Vulnerability to arrhythmias was evaluated during daily undisturbed conditions and following β-adrenergic stimulation. Results: HRV analysis and HR responses to autonomic blockades revealed that 19-month-old mice had a lower vagal modulation of cardiac function compared with 4-month-old mice. This age-related autonomic effect was not reflected in changes in HR, since intrinsic HR was lower in 19-month-old compared with 4-month-old mice. Both time- and frequency-domain HRV indexes were reduced following muscarinic, but not β-adrenergic blockade in younger mice, and to a lesser extent in older mice, suggesting that HRV is largely modulated by vagal tone in mice. Finally, 19-month-old mice showed a larger vulnerability to both spontaneous and isoprenaline-induced arrhythmias. Conclusion: The present study combines HRV analysis and selective pharmacological autonomic blockades to document an age-related impairment in cardiac vagal modulation in mice which is consistent with the human condition. Given their short life span, mice could be further exploited as an aged model for studying the trajectory of vagal decline with advancing age using HRV measures, and the mechanisms underlying its association with proarrhythmic remodeling of the senescent heart. [ABSTRACT FROM AUTHOR]

Cardiovascular regulatory mechanisms that fail to compensate for ultrafiltration and cause hypovolemia during hemodialysis (HD) are not completely understood. This includes the interaction between the autonomic nervous system and the biochemistry that regulates blood pressure and modulates cardiac activity and vascular tone in response to hypovolemia in patients treated with HD. The objective was to evaluate the association of spectral indices of heart rate variability (HRV) with serum levels of angiotensin II, angiotensin 1–7, nitric oxide and total antioxidant capacity during HD. Electrocardiographic records were obtained from 20 patients during HD (3 h), from which HRV data and spectral power data in the very-low-frequency (VLF), low-frequency (LF) and high-frequency (HF) bands were generated. Three blood samples per patient were collected during HD (0.0, 1.5, 3.0 h) to determine the levels of biomarkers involved in the pressor response during HD. Angiotensin II had a positive correlation with VLF (r = 0.390) and with LF/HF (r = 0.359) and a negative correlation with LF (r = −0.262) and HF (r = −0.383). There were no significant correlations between HRV and the other biomarkers. These results suggest that during HD, VLF could reflect the serum levels of angiotensin II, which may be associated with the autonomic response to HD.

This study evaluated the effect of increased physical activity on high-frequency (HF) heart rate variability (HRV) during the first hour after sleep onset in patients with hypertension and/or stable angina pectoris. Physical activity and HF were measured using activity monitors and 24-hour Holter monitors at baseline and 6 months later. The physical activity increased in 28 patients (increase group) and decreased in 20 patients (decrease group) after 6 months. In this study, after 6 months, compared to the decreased physical activity group, the increased physical activity group showed a significant increase in the HF index during the first hour after sleep onset. Therefore, the increase in the HF index may have been due to the increase in physical activity. An increase in physical activity suggests that the quality of sleep early in the sleep cycle may be improved, which may affect the patient's prognosis. [ABSTRACT FROM AUTHOR]

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Summary Objective To compare ventilatory threshold (VT) and heart rate variability threshold (HRVT) in normal weight (NW: 22.75 ± 1.66 kg/m 2 ), overweight (Ov: 27.03 ± 1.48) and obese (O: 33.26 ± 2.39) young people (21.46 ± 2.06 years old). Methods The HRVT was determined at the first intensity with a SD1 index (HRVT SD1 ) and RMSSD (HRVT RMSSD ) lower than 3 ms and with a visual deflection in the curve of intensity versus SD1 (HRVT SD1-v ) and RMSSD (HRVT RMSSD-v ) indexes. Results The HRVT SD1 , HRVT SD1-V and HRVT RMSSD-V were identified in 100% of individuals and the HRVT RMSSD in 90.32%. The VT was identified at similar workloads (NW: 109.50 ± 36.09; Ov: 90.00 ± 16.20; O: 96.00 ± 25.69 W) and VO 2 (NW: 20.52 ± 6.01; Ov; 18.01 ± 4.35; O: 15.14 ± 2.45 mL/kg/min), no differences ( P > 0.05) among the HRVT and groups. Despite the correlations between VT and the diverse HRVT were from low to moderate for workload ( r : 0.25 – 0.42) and VO 2 ( r : 0.38 – 0.62), there was a good agreement between them, mainly HRVT SD1 . Conclusion The criteria and indexes of determination of VT by HRV, especially the HRVT SD1 , can be used, in overweight and obese young people in the evaluation of aerobic fitness and in exercise prescription for this population. [ABSTRACT FROM AUTHOR]

Background: Obesity and aerobic fitness influence resting (HR) and heart rate recovery (HRR), and the evaluation of these parameters show a relevant clinical application. Purpose: This study aimed to evaluate the influence of body mass index (BMI) and aerobic fitness on HRR after maximal exercise in healthy young men. Methods: Twenty nine untrained men (21.37 ± 2.11 years) were divided according to BMI (normal weight ≤24.9, overweight ≥25 and obese ≥30 kg m) and subsequently divided into higher aerobic fitness (125.00 ± 21.71 W) and lower aerobic fitness (72.69 ± 24.38 W), based on the median (105 W) aerobic fitness assessed through the workload at the heart rate variability threshold (HRVT). Results: There were no differences ( p > 0.05) for HR, aerobic fitness or HRR between the three BMI groups. Blood glucose and lipid profile were similar among groups, regardless of BMI and aerobic fitness. However, the young men with higher aerobic fitness showed lower HR (70.48 ± 6.54 vs 81.54 ± 6.46 bpm), HRR (163.1 ± 9.2 vs 170.1 ± 7.6 bpm), HRR (147.2 ± 7.4 vs 154.6 ± 8.1 bpm) and HRR (139.2 ± 6.9 vs 145.8 ± 8.0 bpm), compared to their pairs with lower aerobic fitness. Additionally, HR and the HRVT workload were significantly ( p < 0.05) associated with HRR ( r 0.49 and −0.49), HRR ( r 0.60 and −0.53), HRR ( r 0.53 and −0.47) and HRR ( r 0.48 and −0.47). Conclusions: Aerobic fitness influenced HR and HRR in untrained young men, regardless of BMI. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To analyze the heart rate variability in patients with mild to moderate systemic arterial hypertension. METHODS: Thirty-two healthy (group I) and 70 systemic arterial hypertensive (group II) individuals, divided according to age (40 to 59 and 60 to 80 years old, respectively) and with a similar distribution by sex were studied. Thirty-one had left ventricular hypertrophy (LVH), 22 were overweight, and 16 had Type II diabetes mellitus. Smoking, alcohol ingestion, and sedentary habits were the same between groups. Variability in heart rate was analyzed in the time domain, using standard deviations of normal RR intervals (SDNN) and the differences between maximal brady- and tachycardia (D-BTmax) during sustained inspiration. Analysis of the frequency band of the power spectrum between 0.05 and 0.40 Hz at rest and during controlled respiration was chosen for analysis of the frequency domain. RESULTS: In both time and frequency domains, variables were lower in group II than in group I. Within groups, statistically significant variables were only found for individuals in the 40 to 59 year old group. The presence of LVH, overweight, or diabetes mellitus did not influence the variability in heart rate to a significant extent. CONCLUSION: Variability in heart rate was a valuable instrument for analyzing autonomic modulation of the heart in arterial hypertension. The autonomic system undergoes significant losses in cardio-modulatory capacity, more evident in subjects between 40 and 59 years old. In those over 60 years old, reduced variability in heart rate imposed by aging was not significantly influenced by the presence of systemic arterial hypertension.