Search Results
Results 401 - 450 of 814
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Monahan Kevin D - - 2005
Animal studies suggest that prostanoids (i.e., such as prostacyclin) may sensitize or impair baroreceptor and/or baroreflex responsiveness depending on the site of administration and/or inhibition. We tested the hypothesis that acute inhibition of cyclooxygenase (COX), the rate-limiting enzyme in prostanoid synthesis, impairs baroreflex regulation of cardiac period (R-R interval) and ...
Matsui Takemi - - 2004
In offline analysis, very low frequency variability in RR interval and systolic arterial pressure has been reported below 0.1 Hz during head-up tilt (HUT) tests in conditions similar to hypovolemic states in humans. We designed a real time and non-invasive monitoring system of very low frequency RR interval variability to ...
Sharma Rajesh K - - 2004
The present study explored the possibility of short duration of supervised physical training on cardiovascular performance and attempted to look into the changes in the autonomic tone as assessed by heart rate variability (HRV), if any. The study was conducted on 25 healthy adult male subjects (mean age: 32.08+/-8.32 years) ...
Matsunaga Atsuhiko - - 2004
BACKGROUND: The adaptation of patients with acute myocardial infarction (AMI) to a phase I rehabilitation program has not been widely assessed. METHODS AND RESULTS: Forty-two male patients (62+/-8 years) with AMI were classified as exercise tolerant (group A, n=25) or excessive response (systolic blood pressure (SBP) increase >30 mmHg during ...
Pichon Aurélien P - - 2004
PURPOSE: To investigate the effects of strenuous exercise on heart rate variability (HRV). METHODS: We evaluated the effects of exercise intensity and duration on HRV indices in 14 healthy trained subjects. Each subject exercised for 3, 6, and 9 min at 60 and 70% of the power achieved at maximal ...
Perlitz V - - 2004
A 0.15-Hz rhythm band in cutaneous blood oscillations in awake human subjects was studied in cardiovascular-respiratory time series of five subjects relaxing naïvely or practicing hypnoid relaxation (autogenic training, or AT). Time series analysis used nonlinear algorithms, time-frequency distribution (TFD), postevent scan (PES) method, and linear fast Fourier transform (FFT) ...
Roche Frédéric - - 2004
Chronotropic incompetence (CI), characterized by an attenuated heart rate (HR) response to exercise could participate to the limitation of exercise capacity in anorexia nervosa (AN). Therefore, we evaluated the role of cardiac sympathetic responsiveness in AN patients. In addition, the ambulatory value of autonomic control using spectral analysis of heart ...
Tabor Zbisław - - 2004
This study investigated the problem of the influence of 50 Hz magnetic field (MF) on human heart rate variability (HRV). The exposure system was a commercial device for magnetotherapy, generating field of the strength of 500 microT at the center of the coil, 150-200 microT at the position of human ...
Momen Afsana - - 2004
During exercise, reflex renal vasoconstriction maintains blood pressure and helps in redistributing blood flow to the contracting muscle. Exercise intolerance in heart failure (HF) is thought to involve diminished perfusion in active muscle. We studied the temporal relationship between static handgrip (HG) and renal blood flow velocity (RBV; duplex ultrasound) ...
Baynard Tracy - - 2004
OBJECTIVES: To determine whether autonomic dysfunction explains chronotropic incompetence observed in persons with Down syndrome (DS) and to measure heart rate variability (HRV) at rest and during exercise in persons with mental retardation with and without DS. DESIGN: Comparative study. SETTING: University exercise science laboratory. PARTICIPANTS: Thirty-one subjects with mental ...
Mourot Laurent - - 2004
Heart rate variability (HRV) was assessed during the short- (within 1 h) and long- (within 48 h) term recovery following a single bout of either constant (CST) or interval training (SWEET) exercise performed at the same total physical work [9.4 (0.3) kJ kg(-1)]. R-R intervals, systolic (SAP) and diastolic (DAP) ...
Lee Myeong Soo - - 2004
Heart rate variability was compared in 20 subjects wearing multifunctionalfabric (experimental sessions) and cotton (control sessions) clothing. Anxiety, depression, fatigue, and stress levels were lower and emotional levels were higher during the experimental sessions than in the control sessions. Multifunctional fabrics reduced the low-frequency/high-frequency power ratio of heart rate variability. ...
Jouanin Jean-Claude - - 2004
We studied the effects of prolonged physical activities on resting heart rate variability (HRV) during a training session attended by 23 cadets of the French military academy. This course lasts 1 month and is concluded by a 5-day field exercise simulation with physical and psychological stress. Data collection took place ...
Pober David M - - 2004
PURPOSE: Chronic exercise training has been shown to have a positive influence on cardiac autonomic function as assessed by measures of heart rate variability (HRV). Recent evidence indicates that several benefits associated with exercise training (e.g., improved insulin action, reduced blood pressure, improved blood lipid profile) may be realized transiently ...
Brown C Ann - - 2004
This study examined the claim made by Niemela et al. (1992) that the decline in heart rate variability after coronary artery bypass graft surgery is irreversible. We tested six women and 16 men six and 12 weeks postoperative in three postures: in the supine position, in the standing position, and ...
Baevsky R M - - 2004
The heart rate variability estimation was used for autonomous regulation diagnostic in the 7-day head down bedrest experiment (HDBR). The new device "Pneumocard" and the fix respirations test were applied. The growth of sympathetic activity of autonomous nervous system and reduction of functional reserves of regulation mechanisms were observed in ...
Sergueef N - - 2004
PRIMARY OBJECTIVE: The dominant, 0.1 Hz frequency, Traube-Hering component of blood flow velocity, which is related to baroreflex activity, may be modulated through the established techniques of manipulative medicine. Light exercise programmes, appropriate for use by the elderly and collectively termed gymnastique douce, also are believed to impact the baroreflex ...
Corvera-Tindel Teresita - - 2004
BACKGROUND/OBJECTIVES: Exercise training is an emerging therapy in heart failure (HF). However, factors influencing noncompliance to exercise have not been evaluated. We assessed clinical factors, functional status, and emotional predictors of noncompliance to a 12-week home walking exercise program. METHODS: Using a correlational design, we evaluated noncompliance of 39 HF ...
Chan Chang-Chuan - - 2004
We conducted a study on two panels of human subjects--9 young adults and 10 elderly patients with lung function impairments--to evaluate whether submicrometer particulate air pollution was associated with heart rate variability (HRV). We measured these subjects' electrocardiography and personal exposure to number concentrations of submicrometer particles with a size ...
Yoshiuchi Kazuhiro - - 2004
Although a number of studies have reported alterations in cardiac autonomic nervous system function in chronic fatigue syndrome (CFS), the results are not consistent across studies. Reasons for these discrepancies include (1) the use of a heterogeneous patient sample that included those with orthostatic postural tachycardia (POTS), a condition with ...
Kim Jong-Kyung - - 2004
Arterial baroreflex function is well preserved during dynamic exercise in normal subjects. In subjects with heart failure (HF), arterial baroreflex ability to regulate blood pressure is impaired at rest. However, whether exercise modifies the strength and mechanisms of baroreflex responses in HF is unknown. Therefore, we investigated the relative roles ...
Rietmann T R - - 2004
The objective of this study was to compare the stress response of horses suffering from laminitis after short- and long-term treatment with the intent to evaluate power spectral analysis of heart rate variability (HRV) for pain monitoring. Data were collected from 19 horses with acute or chronic exacerbating laminitis without ...
Kato M - - 2004
Postprandial gastric myoelectrical activity recorded by electrogastrogram (EGG) with the subject in a supine position has shown to be enhanced after moderate-intensity pedaling exercise in an upright seated position, despite the suppression of vagal nerve activity. However, it is still unknown whether the effect is due to the exercise itself ...
Mizumaki Koichi - - 2004
INTRODUCTION: In Brugada syndrome, ventricular fibrillation (VF) occurs mainly during sleep, and Brugada ECG signs are intensified by parasympathomimetic drugs; therefore, vagal activity could be a precipitating factor of VF. The aim of the present study was to elucidate the relation between spontaneous augmentation of ST elevation and changes in ...
Jurca Radim - - 2004
BACKGROUND: Regular exercise is associated with increased heart rate variability (HRV). However, results from studies examining the effect of exercise training on HRV in postmenopausal women are inconclusive. In addition, the effect of hormone replacement therapy (HRT) on HRV remains a subject of speculation. METHODS: We examined 88 sedentary postmenopausal ...
Buchheit M - - 2004
The purpose of this study was to investigate sympathovagal balance as inferred from heart rate variability (HRV) responses to acute hypoxia at rest and during exercise. HRV was evaluated in 12 healthy subjects during a standardized hypoxic tolerance test which consists of four periods alternating rest and moderate exercise (50 ...
Campbell H A - - 2004
Anaesthesia and minor surgery to place electrocardiogram recording electrodes in the short-horned sculpin caused a decrease in mean normal beat (R-R) interval and heart rate variability (HRV), measured as the standard deviation in the R-R interval (SDRR). Mean R-R interval increased to a steady state value (1.9+/-2.9 s) 72 h ...
Liu Jinsong - - 2004
This study investigated the effect of gastric electrical stimulation (GES) on vagal activity and its possible vagal afferent-mediated mechanisms. Sixty rats implanted with gastric serosal electrodes were divided into six groups (control, vehicle, local capsaicin, perivagal capsaicin, systemic capsaicin, and vagotomy). GES with six sets of parameters was performed in ...
Chiladakis John A - - 2004
We investigated the autonomic effects of short-term, single- and dual-chamber pacing by evaluating frequency-domain indexes of heart rate variability (HRV). The study group comprised 25 patients (mean age 62 +/- 7 years) without organic heart disease and with normal sinus node function who were implanted with a permanent dual-chamber DDD ...
Buchheit Martin - - 2004
PURPOSE: Aging is associated with decreased heart rate variability (HRV). As aerobic training is known to increase HRV, the purpose of this study was to evaluate the influence of long-term lifestyle on HRV in very old adults with regard to their usual physical activity. METHODS: Twenty-four older adults (mean 75.7 ...
Ng Leong L - - 2004
Urocortin (UCN), a member of the corticotrophin-releasing factor family, is expressed in heart, brain and gut. UCN has potent cardiostimulatory, cardioprotective, vasodilator and diuretic/natriuretic effects, and cardiac UCN expression is increased in heart failure (HF). In the present study, we investigated plasma levels of UCN in 119 patients with HF ...
Cottin Francois - - 2004
PURPOSE: To examine whether differences in heart rate variability (HRV) can distinguish sub- from supra-ventilatory-threshold exercise and whether the exercise duration at supra-threshold intensity alters cardiorespiratory synchronization. METHODS: Beat-to-beat RR interval, VO2, VCO2, VE, and blood lactate concentration of 11 healthy well-trained young subjects were collected during two exercise tests: ...
Sharma Rajesh K - - 2004
This study reports the results of 15 days of exercise training in 25 adult males on cardiovascular autonomic response amplitude and latencies. A standard battery of autonomic function tests including both activity (tone) and reactivity was used. Parasympathetic activity as evaluated from Heart rate variability (HRV) showed no statistically significant ...
Nagai Yoko - - 2004
Negative amplitude shifts of cortical potential are related to seizure activity in epilepsy. Regulation of the cortical potential with biofeedback has been successfully used to reduce the frequency of some patients' seizures. Although such behavioural treatments are increasingly popular as an alternative to pharmacotherapy, there has been no investigation of ...
Sack Martin - - 2004
BACKGROUND: There is extensive evidence that the parasympathetic branch of the autonomic nervous system can modulate psychophysiological arousal. To date, no studies have investigated associations between cardiac vagal tone and the time course of arousal during exposure to trauma-related stimuli in posttraumatic stress disorder (PTSD). METHODS: Thirty-one subjects, 29 with ...
Lucini Daniela - - 2004
We examined on 56 (age 38+/-2 [range: 16-60] years) healthy subjects the effects of aging on cardiovascular autonomic responses to progressive supine bicycle exercise of light intensity. Autoregressive spectral analysis of RR interval and systolic arterial pressure (SAP) variabilities provided measures of the exercise-induced changes in baroreflex gain (by index ...
Uusitalo Arja L T - - 2004
We studied the effect of regular physical activity on cardiac and vascular autonomic modulation during a 5-yr controlled randomized training intervention in a representative sample of older Finnish men. Heart rate variability (HRV) and blood pressure variability (BPV) are markers of cardiac and vascular health, reflecting cardiac and vascular autonomic ...
Banach Tomasz - - 2004
BACKGROUND: Linear relationship between the increase of heart rate (HR) and the power output (PO) during sub-maximal exercise is well documented. However the study considering the effect of progressive increase of PO on the parameters of heart rate variability (HRV) remain scarce. AIM: This study investigated changes of the HRV ...
Princi Tanja - - 2004
The analysis of heart rate variability (HRV) is recognized as a powerful non-invasive tool to evaluate the influence of autonomic nervous system on the heart and the heart-brain interaction. It is well-known that relatively high HRV is correlated to health condition while low HRV corresponds to cardiovascular disease or could ...
Zhang Cuntai - - 2004
The effect of the autonomic nerves on the transmural dispersion of ventricular repolarization in intact canine was investigated. By using the monophasic action potential (MAP) recording technique, monophasic action potentials (MAPs) of the epicardium (Epi), midmyocardium (Mid) and endocardium (Endo) were recorded simultaneously by specially designed plunge-needle electrodes at the ...
Alm Per A - - 2004
Persons who stutter often report their stuttering is influenced by emotional reactions, yet the nature of such relation is still unclear. Psychophysiological studies of stuttering have failed to find any major association between stuttering and the activity of the sympathetic nervous system. A review of published studies of heart rate ...
Jacobs Stephan - - 2003
BACKGROUND: Surgical performance is limited by human factors. Beating-heart surgery requires full dexterity and motion tracking. Currently techniques for total endoscopic beating-heart bypass grafting using telemanipulation systems are being developed. The aim of this study was to assess the limitations for manual and telemanipulator-assisted motion tracking using the da Vinci ...
Leicht Anthony S - - 2003
The current study examined whether changes in heart rate variability (HRV) following intensive cycling training contribute to the mechanism of training-induced bradycardia. Thirteen healthy untrained subjects, ages 18-27 years, underwent recordings of heart rate (HR) and VO2max before and after 8 weeks of cycling, 25-60 min/day, 5 days/week at > ...
Bosquet L - - 2003
AIM: The purpose of the study was to examine whether an unaccustomed increase in training volume would result in characteristics changes in heart rate variability (HRV), in order to determine if this marker can be used to diagnose overtraining. METHODS: Nine experienced endurance athletes increased their usual amount of training ...
Arlt Josef - - 2003
BACKGROUND: Heart rate variability represents a reliable marker to delineate the status of autonomic nervous system (ANS) function and alterations due to stress in vivo. Interestingly, up to now the effects of corticotropin-releasing hormone (CRH), a key regulator of the stress hormone system, upon heart rate variability are not sufficiently ...
Kaya Dayimi - - 2003
AIM: Long-term estrogen replacement therapy has favorable results on autonomic cardiovascular functions in postmenopausal women. Although acute estrogen administration has beneficial modulations on autonomic tone in animal studies, there are still controversies about the effects of acute estrogen on autonomic modulation to the heart in humans. The aim of this ...
Dingli K - - 2003
A recent study has shown that daytime heart rate variability is reduced in obstructive sleep apnoea/hypopnoea syndrome (OSAHS) patients. In the present study, the hypothesis was that sympathovagal balance around apnoeas/hypopnoeas and nocturnal autonomic activity are altered in OSAHS patients. Frequency- and time-domain analyses of RR intervals were performed to ...
Welzig C Michael - - 2003
We have previously demonstrated in an in vitro model for lipid lowering that lipoprotein depletion resulted in a marked increase in the negative chronotropic response to the acetylcholine analogue carbamylcholine. In this study we used heart rate variability analysis to determine the effect of lipid lowering by statins on the ...
García-González M A - - 2003
A new index for the analysis of the heart rate variability (HRV) dynamics is presented. The proposed index (acceleration change index (ACI)) characterizes the sign of the differences of a time series. A theoretical study shows an expression that relates ACI and the autocorrelation function of the time series. This ...
Agostoni Piergiuseppe - - 2003
BACKGROUND: In heart failure (HF) patients, exercise may increase pulmonary capillary hydrostatic pressure and thereby generate pulmonary edema. If pulmonary edema developed, alveolar-capillary membrane conductance (Dm), measured immediately after exercise, would decrease. To test this hypothesis, we measured Dm before and at 2 and 60 minutes after exercise. METHODS AND ...
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