Search Results
Results 251 - 300 of 814
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Porta Alberto - - 2007
Complexity (or its opposite, regularity) of heart period variability has been related to age and disease but never linked to a progressive shift of the sympathovagal balance. We compare several well established estimates of complexity of heart period variability based on entropy rates [i.e., approximate entropy (ApEn), sample entropy (SampEn), ...
Theorell Töres - - 2007
Musicians are sensitive to changes in their work environment. A 2-year longitudinal study with repeated observations was performed in two professional symphony orchestras. A representative sample from each one of them was selected, 15 and 16 members respectively. In one of them a wind player fainted twice in front of ...
Pagkalos M - - 2008
OBJECTIVES: Cardiac autonomic neuropathy (CAN) as a result of diabetic autonomic neuropathy is positively related to a poor prognosis in diabetic patients. The measurement of heart rate variability (HRV) is a remarkable index of cardiac autonomic dysfunction. The aim of this study was to examine the effects of long-term exercise ...
Lewis M J - - 2007
Sample entropy (SampEn) is a measure of the complexity of data. Few studies have compared the SampEn of electrocardiographic cardiac interval (RR) data (SampEn-RR) during differing physiological states, and none have examined SampEn for the corresponding QT interval (SampEn-QT). The aim of this study was to quantify SampEn-RR and SampEn-QT ...
Siira S - - 2007
OBJECTIVE: To find whether low-to-high frequency (LF/HF) ratio of fetal heart rate (FHR) variability changes in relation to a significant ST-event during delivery, and if the change is predictive of metabolic acidosis of the newborn. DESIGN: A case-control study. SETTING: Data from a multicentre project. SUBJECTS: Acidotic and control fetuses ...
Castillo Martínez Lilia - - 2007
OBJECTIVE: Patients with chronic heart failure (HF) develop important changes in body composition. Nevertheless, the usual methods of body composition assessment can be misleading in patients with HF because tissue hydration is altered. Bioelectrical impedance vector analysis (BIVA) works without making any assumption about constant soft tissue hydration. In this ...
Fraga Raffael - - 2007
Evidence suggests that carvedilol decreases muscle sympathetic nerve activity (MSNA) in patients with heart failure (HF) but carvedilol fails to improve forearm vascular resistance and overall functional capacity. Exercise training in HF reduces MSNA and improves forearm vascular resistance and functional capacity. To investigate whether the beneficial effects exercise training ...
Bosquet Laurent - - 2007
The aim of this study was to determine if subjects matched for VO2max but with differing aerobic endurance displayed similar heart rate variability (HRV) at rest and heart rate recovery (HRR) after maximal exercise. We hypothesized that the higher the aerobic endurance, the higher the HRV and the faster the ...
Figueroa Arturo - - 2007
Obesity and type 2 diabetes (T2D) are associated with abnormal cardiovascular autonomic function and increased risk for cardiac complications, especially after exercise. Since improvements at rest are not always observed after training, we investigated changes in resting and post-exercise autonomic function in obese women with and without T2D after16-week of ...
Shin Ki Ok - - 2007
We investigated whether capsaicin ingestion (150 mg) enhances substrate oxidation associated with thermogenic sympathetic activity as an energy metabolic modulator without causing prolongation of the cardiac OT interval during aerobic exercise in humans. Ten healthy males [24.4 (4.3) y] volunteered for this study. The cardiac autonomic nervous activities evaluated by ...
Weinstein Ali A - - 2007
INTRODUCTION/PURPOSE: Negative mood symptoms occur frequently in sedentary populations, but individual vulnerability factors for developing these complaints have not been systematically evaluated. This investigation examined whether the autonomic nervous system (ANS) serves a role in the development of negative mood after controlled exercise withdrawal. METHODS: Forty participants (mean age of ...
Krstacic Goran - - 2007
BACKGROUND: Dynamic analysis techniques may quantify abnormalities in heart rate variability (HRV) based on nonlinear and fractal analysis (chaos theory). The article emphasizes clinical and prognostic significance of dynamic changes in short-time series applied on patients with coronary heart disease (CHD) during the exercise electrocardiograph (ECG) test. METHODS: The subjects ...
Bhagyalakshmi Shreedhar - - 2007
BACKGROUND: Heart rate variability (HRV) reflects autonomic nervous system modulation of cardiac activity. There is a relationship between degrees of physical activity, HRV changes and the risk of cardiovascular disease. AIM: To study the effect of a supervised integrated exercise programme on HRV in type 2 diabetes mellitus (DM). METHODS: ...
Chen Jin-Long - - 2007
Studies on the physiology of the cardiovascular system suggested that the generation of the heart rate signal is governed by nonlinear chaotic dynamics. No study investigated the nonlinear dynamics of heart rate in hyperthyroidism. We examined whether the heart rate dynamics of hyperthyroid patients is different from normal controls by ...
Gamelin F X - - 2007
The purpose of this study was to investigate the effect of twelve weeks of aerobic training and eight weeks of training cessation on Heart Rate Variability (HRV). Ten healthy young men (Age: 21.7 +/- 2.2 years; Height: 179.2 +/- 6.9 cm; Mass 72.7 +/- 11.1 kg) completed an incremental test ...
Zyśko Dorota - - 2007
A 49-year-old patient with a history of situational syncope and minimal electrocardiographic signs of accessory pathway is described. The evidence for pre-excitation was present only during the sympathetic activation caused by exercise testing and isoprenaline infusion. This phenomenon served as an indicator of significant adrenergic drive to the heart after ...
Lewis M J - - 2007
Breathing rates during physical exercise suggest that, during these conditions, the high-frequency (HF) bandwidth of heart rate variability (HRV) analysis should be extended beyond conventional guidelines. However, there has been little investigation of the most appropriate choice of HF bandwidth during exercise. HRV analysis was performed in 10 males and ...
Zoppini G - - 2007
AIMS: The purpose of the study was to determine long-term cardiovascular autonomic adaptation to moderate endurance aerobic exercise in people with Type 2 diabetes in order to test the hypothesis of an enhanced vagal drive. METHODS: We analysed the power spectral density of heart rate cyclic variations at rest, while ...
Fleg Jerome L - - 2007
Exercise intolerance is one of the hallmark symptoms of heart failure (HF). Exercise training in this condition was not explored as a therapeutic modality until the past two decades. In fact, bed rest was promoted as a treatment for certain forms of HF in the 1970s. Over the past two ...
Guzik Przemysław - - 2007
AIM: To analyze the correlation of the Poincaré plot descriptors of RR intervals with standard measures of heart rate variability (HRV) and spontaneous baroreflex sensitivity (BRS). A physiological model of changing respiratory rates from 6 to 15 breaths/min provided a wide range of RR intervals for analysis. MATERIAL AND METHODS: ...
Wernicke Dirk - - 2007
Animal models of cardiovascular diseases allow to investigate relevant pathogenetic mechanisms in detail. In the present study, the mutations Asp175Asn and Glu180Gly in alpha-tropomyosin (TPM1), known cause familiar hypertrophic cardiomyopathy (FHC) were studied for changes in hemodynamic parameters and spontaneous baroreflex regulation in transgenic rats in comparison to transgenic and ...
Marocolo M - - 2007
Increased heart rate variability (HRV) and high-frequency content of the terminal region of the ventricular activation of signal-averaged ECG (SAECG) have been reported in athletes. The present study investigates HRV and SAECG parameters as predictors of maximal aerobic power (VO2max) in athletes. HRV, SAECG and VO2max were determined in 18 ...
Dewey Frederick E - - 2007
BACKGROUND: Although the prognostic power of heart rate variability (HRV) at rest has been demonstrated, the prognostic potential of exercise-induced HRV has not been investigated. We aimed to evaluate the prognostic power of exercise-induced HRV during and after standard exercise testing. METHODS: Time- and frequency-domain HRV analysis was performed on ...
Arena Ross A - - 2007
PURPOSE: Beta-blockade (BB) has been shown to improve outcomes among patients with heart failure (HF). The impact this pharmacological approach has on the prognostic information gained from cardiopulmonary exercise testing (CPX) is, however, unclear. METHODS: Four hundred seventeen subjects diagnosed with HF underwent CPX. The numbers of subjects prescribed and ...
Tzeng Y C - - 2007
Normally, at rest, the amplitude of respiratory sinus arrhythmia (RSA) appears to correlate with cardiac vagal tone. However, recent studies showed that, under stress, RSA dissociates from vagal tone, indicating that separate mechanisms might regulate phasic and tonic vagal activity. This dissociation has been linked to the hypothesis that RSA ...
Jae Sae Young - - 2007
This study was conducted to test the hypothesis that slow and abnormal heart rate recovery (HRR), an indicator of decreased autonomic nervous system activity, after exercise is associated with inflammatory markers. Subjects who underwent exercise treadmill testing (n = 5,527, mean age 50.4 +/- 8.5 years) were studied in a ...
Guijt Alida M - - 2007
BACKGROUND: A variable that remains stable over repeated measurements (in stable conditions) is ideal for tracking modifications of the clinical state. The aim of the present study is to examine test-retest reliability of time-domain heart rate variability and respiration rate measurements using a portable device on normal subjects during rest ...
Wilén Jonna - - 2007
In a previous study, we showed that operators of radiofrequency (RF) plastic sealers, RF operators (n = 35) had a lower heart rate during nighttime compared to a control group (n = 37). We have analyzed the heart rate variability (HRV) on the same group of people to better understand ...
Aoyagi N - - 2007
OBJECTIVES: The investigation of the relation between the long-range correlation property of heart rate and autonomic balance. METHODS: An investigation of the fractal scaling properties of heart rate variability was carried out by using detrended fluctuation analysis (DFA). Eleven healthy subjects were examined for two consecutive days, which included usual ...
Zdrenghea D - - 2007
Both heart variability (HRV) and heart rate recovery (HRR) after exercise are considered to reflect the sympathetic-vagal balance and low values of them have negative prognostic significance, especially in ischemic patients. The main goal of the research was to establish if there is a correlation between HRR and HRV in ...
Corino Valentina D A VD Department of Biomedical Engineering, Politecnico di Milano, Via Golgi 39, 20133 Milano Italy. - - 2007
During atrial fibrillation (AF), time-frequency analysis of atrial signal has been applied to describe fibrillatory frequency trends. Recently, temporal changes in spectral shape have been investigated using the spectral profile technique. This profile is computed recursively by fitting each short-time log-spectrum to a spectral template, using amplitude scaling and frequency ...
Vallais Frédéric F Dipartimento di Bioingegenria, Politecnico di Milano, Piazza Leonardo da Vinci, 20133 Milan, Italy. - - 2007
Ten estimates of baroreflex sensitivity (BRS) were compared during progressive graded exercise: they were computed from sequence method, spectral and cross-spectral analysis methods, and parametric model-based methods. Results showed baroreflex control of heart rate (HR) changes as a function of the intensity of exercise, as well as the resetting phenomenon. ...
Sala-Mercado Javier A - - 2007
Underperfusion of active skeletal muscle elicits a reflex pressor response termed the muscle metaboreflex (MMR). In normal dogs during mild exercise, MMR activation causes large increases in cardiac output (CO) and mean arterial pressure (MAP); however, in heart failure (HF) although MAP increases, the rise in CO is virtually abolished, ...
Brown S J - - 2007
This study used measures of heart rate variability during recovery from high-intensity exercise in trained Master athletes to examine postexercise cardiac autonomic regulation. Seven males (mean age 52.1 +/- 3.3 yr; mass 85.1 +/- 18.0 kg) and 6 females (mean age 50.5 +/- 2.9 yr; mass 63.1 +/- 6.0 kg) ...
Núñez Julio - - 2007
To assess whether circulating levels of carbohydrate antigen 125 (CA125) predict subsequent 6-month all-cause mortality in patients after the index hospitalisation for acute heart failure (HF). Prospective cohort study at a single teaching centre in Spain. 529 consecutive patients with acute HF admitted in a single university centre were analysed. ...
Park Sung Kyun - - 2006
BACKGROUND: Particulate air pollution has been associated with cardiovascular mortality and morbidity. Transition metals such as iron bound to the particles may be responsible for those associations. The protein product of the hemochromatosis (HFE) gene modulates uptake of iron and divalent cations from pulmonary sources and reduces their toxicity. Two ...
Reid G M - - 2007
The human foetus begins preparation for extrauterine life in the 26th week of gestation. Victims of sudden infant death syndrome (SIDS) were described as having less-intensive reactions to environmental stimuli than their siblings. They were described as less-active physically and more breathless and exhausted during feeding. These foetal-like qualities are ...
Davrath Linda R - - 2006
The reduction in heart rate (HR) during the first minute of recovery immediately after a graded maximal exercise stress test (GXT) has recently been found to be a powerful and independent predictor of cardiovascular and all-cause mortality. Reduced vagal activity has been postulated as the cause, but this has not ...
Mehmet Unlu, Mehmet Melek, ...
Aim: Anticholinergic drugs may alter cardiac autonomic modulation. The aim of this study was to investigate the effects of inhaled tiotropium on heart rate variability (HRV). Methods: A randomized, double-blind, crossover design study was conducted on 11 healthy volunteers. Tiotropium or placebo was administered in two different testing sessions. Time ...
Buchheit M - - 2007
The amount and type of physical activity (PA) appropriate in youth for optimal health is still being discussed. The purpose of this study on 12-year-old preadolescents is to evaluate the association of two PA patterns, corresponding to different exercise intensities, with some health-related indexes. PA was evaluated by triaxial accelerometry ...
Atlaoui D - - 2007
The aim of the present study was to investigate the relationships between heart rate variability (HRV) changes and both training variations and performances in elite swimmers. A secondary purpose was to measure catecholamine urinary excretion in elite swimmers to validate the HRV indices of sympathetic activity during training. Thirteen swimmers ...
Dewland, Thomas Andrew
Acetylcholinesterase inhibition with pyridostigmine has been previously studied in patients with congestive heart failure (CHF), but the effects of this medication on heart rate recovery after exercise and other indices of parasympathetic activity in populations with greater baseline vagal tone has not been fully characterized. Ten healthy, sedentary adults and ...
Okano Y - - 2007
There are many reports indicating that night time blood pressure (BP) is closely associated with target organ damage. However, BP in the waking period is influenced by physical activity and also by the psychological status. Recently, base BP (BP0: minimum and stable BP during sleep) has been reported to correlate ...
Yin Qing-zhu - - 2006
Constraining the timing of the formation of Earth's core, which defines the birth of our planet, is essential for understanding the early evolution of Earth-like planets. Wood and Halliday and Halliday discuss the apparent discrepancy between the U-Pb (60-80 Myr) and Hf-W clocks (30 Myr) in determining the timescale of ...
Grossman Paul - - 2007
Respiratory sinus arrhythmia (RSA, or high-frequency heart-rate variability) is frequently employed as an index of cardiac vagal tone or even believed to be a direct measure of vagal tone. However, there are many significant caveats regarding vagal tone interpretation: 1. Respiratory parameters can confound relations between RSA and cardiac vagal ...
Cottin F - - 2007
The present study examined whether the ventilatory thresholds during an incremental exhaustive running test could be determined using heart rate variability (HRV) analysis. Beat-to-beat RR interval, V(.-)O (2), V(.-)CO (2) and V(.-) (E) of twelve professional soccer players were collected during an incremental test performed on a track until exhaustion. ...
Baumert Mathias - - 2006
Heart rate variability (HRV) reflects regulatory processes of the cardiovascular system and reveals fractal characteristics. In this paper we investigated standard HRV parameters and scaling characteristics in ten athletes before, during, and after a 2-week training camp to assess the effects of short-term overtraining on cardiovascular control. High-resolution ECGs were ...
Sumi K - - 2006
The purposes of this study were to demonstrate the transition of heart rate variability (HRV) during trials in the field and to examine the relationship between peak frequency of high-frequency band (HF) and stride frequency. Ten healthy long-distance college female runners (age 19-21 years) performed a 3000 m realistic time ...
Bruce-Low Stewart S - - 2006
INTRODUCTION: This study observed heart rate variability (HRV) measured in order to detect the changes in sympathovagal activity during high ambient (74 degrees C) temperature. HRV is a measure of heart rate (HR) fluctuations around the mean HR and has been used to indicate the balance between parasympathetic and sympathetic ...
Baumert Mathias - - 2006
OBJECTIVE: To assess the effects of abruptly intensified physical training on cardiovascular control. DESIGN: Retrospective longitudinal study. SETTING: Research laboratory. PARTICIPANTS: Ten healthy athletes (5 men and 5 women) from track and field as well as triathlon. INTERVENTIONS: A 2-week training camp, including daily stepwise increasing cycling tests, running of ...
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