Search Results
Results 251 - 300 of 802
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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 ...
Corino Valentina D A - - 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 ...
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 ...
Vallais Frédéric - - 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 ...
Galetta F - - 2006
BACKGROUND: The aim of this study was to determine whether endothelial function and inappropriate peripheral vasomotion have a significant role in the pathogenesis of neurally mediated syncope. METHODS: In 16 patients (mean age 28.2+/-5.8 years) with previous vaso-vagal syncope and in matched healthy subjects, endothelium-dependent flow-mediated dilation (FMD) and endothelium-independent ...
Cottin F - - 2006
REASONS FOR PERFORMING STUDY: Interval training is a commonly used training method for trotting horses. In addition, trainers are provided with efficient and inexpensive heart rate monitor devices for the management of training. HYPOTHESIS: Since the high frequency (HF) frequency peak (fHF) of heart rate variability (HRV) corresponds to the ...
Kinnunen S - - 2006
REASONS FOR PERFORMING STUDY: Endurance training induces changes in autonomic nervous system functions. High intensity training includes the risk of overtraining, in man and horse. Heart rate variability (HRV) is a noninvasive measurement of the autonomic regulation of the heart rate, which is quick and easy to measure with modern ...
Lipsett Michael J - - 2006
Alterations in cardiac autonomic control, assessed by changes in heart rate variability (HRV), provide one plausible mechanistic explanation for consistent associations between exposure to airborne particulate matter (PM) and increased risks of cardiovascular mortality. Decreased HRV has been linked with exposures to PM10 (PM with aerodynamic diameter<or=10 microm) and with ...
Wecht Jill M - - 2006
INTRODUCTION: Altered autonomic cardiovascular control in persons with paraplegia may reflect peripheral sympathetic denervation caused by the injury or deconditioning due to skeletal muscle paralysis. Parameters of autonomic cardiovascular control may be improved in fit persons with paraplegia similar to effects reported in the noninjured population. PURPOSE: To determine differences ...
Rossi M - - 2006
Cutaneous blood flowmotion (CBF) can contribute to a reduction in the resistance in skin microvascular networks. The increase of CBF during exercise can improve the capacity of skin microvascular networks to transport and eliminate heat. In order to verify if the physical training could increase the skin blood flowmotion during ...
Lee C Matthew - - 2006
BACKGROUND: The purpose of this investigation was to examine cardiac autonomic modulation, as measured by wavelet analysis of heart rate variability, following a series of high-intensity static muscle contractions. METHODS: After 10 minutes of rest, electrocardiograms (ECGs) were collected in 17 participants (age, 24.5 +/- 1 yr) 2.5 minutes before ...
Vuksanović Vesna - - 2007
Previous investigations on arithmetic stress with verbalization showed that spectral measures of heart rate variability (HRV) did not assess changes in autonomic modulation, although the heart rate (HR) increased. In this study non-linear measures of HRV are determined and linear measures are re-examined in order to understand this apparent discrepancy ...
Sandercock G R H - - 2006
Heart rate variability (HRV) is a non-invasive indicator of cardiac autonomic modulation at rest. During rhythmic exercise, global HRV decreases as a function of exercise intensity. Measures reflecting sympathovagal interactions at rest do not behave as expected during exercise. This makes interpretation of HRV measures difficult, especially at higher exercise ...
Wenner Megan M - - 2006
Reproductive hormones such as estradiol and progesterone are known to influence autonomic cardiovascular regulation. The purpose of this study was to determine whether amenorrheic athletes (AA) have impaired autonomic cardiovascular regulation compared with eumenorrheic athletes (EA). Thirty-five athletes were tested: 13 AA (19 +/- 1 yr), 13 EA (21 +/- ...
Tsai Mei-Wun - - 2006
BACKGROUND AND PURPOSE: Cardiac autonomic dysfunction is associated with risk of restenosis and cardiovascular mortality in patients after percutaneous transluminal coronary angioplasty (PTCA). Analysis of heart rate variability (HRV) is an important, widely used method for assessing cardiac autonomic regulation. The purpose of this study was to investigate the effect ...
Perini Renza - - 2006
To evaluate if changes in athletes' physical fitness due to seasonal training are associated with changes in cardiovascular autonomic control, nine swimmers (three males and six females; aged 14-18 years) were evaluated before and after 5 months of training and competitions. Maximal oxygen consumption (VO2max) and ventilatory threshold were determined ...
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