Beat-to-beat heart rate (HR) dynamics were studied by plotting each R-R interval as a function of the previous (Poincare plot) during incremental doses atropine followed exercise for 10 subjects and without autonomic blockade 31 subjects. A quantitative two-dimensional vector analysis Poincare plot was used measuring separately standard deviation instantaneous beat-to-beat variability (SD1) continuous long-term (SD2) well SD1/SD2 ratio. Quantitative measures compared with linear HR (HRV)...

The purpose of this study was to compare the applicability four different measures heart rate variability (HRV) in assessment cardiac vagal outflow, with special reference effect breathing pattern. anticholinergic effects an intravenous glycopyrrolate infusion (5 microg x kg(-1) h(-1) for 2 h) during spontaneous and controlled (15 min(-1)) were investigated eight volunteers, fixed rates (6-15-24 hyperventilation 12 subjects. Cardiac activity assessed by ECG recordings which following HRV...

This study was designed to assess the effects of age and physical fitness on vagal modulation heart rate (HR) during exercise by analyzing instantaneous R-R interval variability from Poincaré plots (SD1) at rest different phases a bicycle test in population healthy males. SD1 normalized for average (SD1 n ), measure activity, compared among subjects ages 24–34 (young, = 25), 35–46 (middle-aged, 30), 47–64 yr (old, 25) matched peak O 2 consumption (V˙o ) withV˙o 28–37 (poor, 38–45 (average,...

Aims Current treatment may have changed the risk profiles of survivors acute myocardial infarction (AMI). We evaluated utility Holter-based variables in prediction sudden cardiac death (SCD) among AMI treated with modern therapy.

Background— Altered fractal heart rate (HR) dynamics occur during various disease states, but the physiological background of abnormal HR behavior is not well known. We tested hypothesis that organization human determined by balance between sympathetic and vagal outflow. Methods Results— A short-term scaling exponent (α 1 ) dynamics, analyzed detrended fluctuation analysis (DFA) method, high-frequency (HF) low-frequency (LF) spectral components R-R intervals (0.15 to 0.4 Hz; n=13), along...

This study was designed to assess the effects of moderate- and high-volume aerobic training on time domain spectral fractal heart rate (HR) variability indexes. Sedentary subjects were randomized into groups with moderate-volume ( n = 20), controls 15). The period 8 wk, including 6 sessions/wk at an intensity 70–80% maximum HR, lasting for 30 min/session in group 60 group. Time domain, frequency short-term scaling measures HR analyzed over a 24-h period. Mean decreased from 70 ± 7 64...

Harmful cardiac events occurs frequently after exercise. However, the autonomic regulation vigorous exercise is not well known. This study was designed to assess heart rate (HR) variability before and a 75 km cross‐country skiing race. HR assessed by using standard statistical measures along with spectral quantitative Poincarè plot analysis of in 10 healthy male subjects (age 36 ± 11 years). The average at same level 1 day race as race, but on second day, significantly lower ( P <0·001)...

tk;1Passive head-up tilt and exercise result in specific changes the spectral characteristics of heart rate (HR) variability as a reduced vagal enhanced sympathetic outflow. Recently analytic methods based on nonlinear system theory have been developed to characterize features HR dynamics. This study was designed assess fractal complexity measures behavior during passive exercise. Fractal exponent (α 1 ) approximate entropy (ApEn), short-term correlation properties overall HR, respectively,...

To test the utility of HR variability (HRV) in daily exercise prescription moderately active (approximately two exercises per week) men and women.A total 21 32 women were divided into standard training (ST: males = 7 females 7), HRV-guided (HRV-I: 7; HRV-II: 10), control (males 8) groups. The 8-wk aerobic period included 40-min at moderate vigorous intensities (70% 85% maximal HR). ST group was instructed to perform or more sessions three intensity weekly. HRV-I HRV-II groups trained on...

Physiological signals, including heart rate (HR), variability (HRV), and respiratory frequency (RF) are important indicators of our health, which usually measured in clinical examinations. Traditional physiological signal measurement often involves contact sensors, may be inconvenient or cause discomfort long-term monitoring sessions. Recently, there were studies exploring remote HR from facial videos, several methods have been proposed. However, previous cannot fairly compared, since they...

Individual responses to aerobic training vary from almost none a 40% increase in fitness sedentary subjects. The reasons for these differences the response are not well known. We hypothesized that baseline cardiovascular autonomic function may influence response. study population included male subjects ( n = 39, 35 ± 9 yr). period was 8 wk, including 6 sessions/wk at an intensity of 70–80% maximum heart rate 30–60 min/session. Cardiovascular assessed by measuring power spectral indexes...

Aging alters cardiac autonomic function, which may contribute to a higher risk of events. Spectral measures HR variability (HRV) and fractal-like behavior are considered as markers healthy heart. The present study examined the effects combining endurance strength training compared with or alone on dynamics physical fitness in older previously untrained men aged 40-67 yr.Subjects were randomized into (E, n = 23), (S, 25), combined (ES, 29), control group (C, 16). Short-term fractal scaling...

Purpose The effects of short-term high-intensity interval training (HIT) on cardiac autonomic function are unclear. present study assessed adaptations to HIT in comparison with aerobic endurance (AET). Methods Twenty-six healthy middle-age sedentary men were randomized into (n = 13, 4–6 × 30 s all-out cycling efforts 4-min recovery) and AET 40–60 min at 60% peak workload) groups, performing six sessions within 2 wk. participants underwent a 24-h ECG recording before after the intervention...

Concomitant sympathetic and vagal activation can occur in various physiological conditions, but there is limited information on heart rate (HR) behavior during the accentuated sympathovagal antagonism. Beat-to-beat HR blood pressure were recorded intravenous infusion of incremental doses norepinephrine 18 healthy male volunteers (mean age 23 ± 5 yr). spectra two-dimensional Poincaré plots generated from baseline recordings at different norepinephrine. The mean increased (from 90 7 to 120 9...

Breakdown of short-term fractal-like behaviour HR indicates an increased risk for adverse cardiovascular events and mortality, but the pathophysiological background altered fractal dynamics is not known. Our aim was to study effects pharmacological modulation autonomic function on correlation properties heart rate (HR) variability in healthy subjects. Short-term scaling exponent (alpha1) along with spectral components were analysed during following interventions subjects: (i) noradrenaline...

Methods based on non-linear heart rate (HR) dynamics have been suggested to probe features in HR behaviour that are not easily detected by the traditional variability indices. This study tested hypothesis analysis of correlation properties R-R intervals provides useful information fluctuation during exercise. High- (HF) and low-frequency (LF) spectral components a short-term scaling exponent (alpha1) variability, were analysed for nine healthy subjects at rest, incremental steady-state...