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Results 301 - 350 of 813
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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 ...
Chen Quansheng - - 2007
Near-infrared (NIR) spectroscopy has been successfully utilized for the rapid identification of green, black and Oolong teas. The spectral features of each category are reasonably differentiated in the NIR region, and the spectral differences provided enough qualitative spectral information for identification. Support vector machine as a pattern recognition was applied ...
Notarius Catherine F - - 2006
BACKGROUND: Caffeine increases submaximal exercise performance in healthy young subjects; its effects on exercise tolerance in heart failure (HF) have not been characterized. METHODS AND RESULTS: To determine whether caffeine increases exercise tolerance in HF, caffeine (4 mg/kg intravenously, equivalent to 2 cups of coffee) or vehicle were infused into ...
Arena Ross - - 2006
BACKGROUND: The rate in which heart rate recovers from exercise has recently been shown to be a strong predictor of mortality in patients suspected of having coronary disease, but its prognostic value in patients with heart failure (HF) has not been explored. We sought to assess the prognostic utility of ...
Baguley Ian J - - 2006
PRIMARY OBJECTIVE: To investigate disconnection theories postulated as the cause of dysautonomia following severe traumatic brain injury (TBI) through analysis of heart rate variability (HRV). METHODS AND PROCEDURES: Data were collected on age-matched subjects with and without dysautonomia (eight subjects in each group) and 16 non-injured controls. Data included injury ...
Evrengul Harun - - 2006
BACKGROUND: Reduced heart rate recovery (HRR) in coronary artery disease (CAD) is predictive of increased cardiovascular mortality and is related to reduced parasympathetic tonus. OBJECTIVE: To investigate HRR and heart rate variability (HRV) measured at steady state condition and the relationship between these two parameters in CAD. MATERIALS AND METHODS: ...
Augustyniak Robert A - - 2006
Rapid recovery of resting hemodynamics from tachycardia- or arrhythmia-induced heart failure (HF) has been demonstrated in both humans and animals. However, little is known about cardiovascular responses to exercise in animals or about reflex control of the cardiovascular system during exercise while recovering from HF. Inasmuch as the reduced cardiac ...
Kaufman Christopher - - 2006
The physiological responses of high (HF) and low fit (LF) individuals at given perceived exercise intensities were compared to ranges provided by the American College of Sports Medicine (ACSM). Participants were 7 LFand 8 HF men between the ages of 22 and 26 years. All participants performed a maximum oxygen ...
Ohmura Hajime - - 2006
OBJECTIVE: To determine whether evaluation of heart rate (HR) and HR variability (HRV) during prolonged road transportation in horses provides a sensitive index of autonomic stimulation. ANIMALS: Five 2-year-old Thoroughbreds. PROCEDURE: ECGs were recorded as horses were transported for 21 hours in a 9-horse van. Heart rate, high-frequency (HF) power, ...
Smith Anne-Louise - - 2006
Multiple indices have been developed to characterise the nonperiodic behaviour of heart rate variability displayed in Poincaré plots, particularly with R-R interval data collected over 24hr periods. Some of these indices have been compared to statistical time-domain indices and some to spectral indices, while others have been used to separate ...
Schmitt L - - 2006
The aim of this study was to compare the effects of training at two different altitudes on heart rate variability (HRV) and performance in well-trained swimmers. Eight national-level male swimmers (age = 17.0 +/- 1.8 yrs, weight = 67.0 +/- 6.6 kg, height = 180.4 +/- 7.2 cm, V(O2max) = ...
Douglas Pamela K - - 2006
Because changes in the 12-lead high-frequency QRS electrocardiogram (HF QRS ECG) more sensitively identify myocardial ischemia than do changes in the ST segments of the conventional ECG, it is important that changes in HF QRS signals that are merely physiological be distinguishable from those that are potentially pathological. We therefore ...
Buchheit Martin - - 2006
The objective of this study was to establish the separate associations between parasympathetic modulations of the heart [evaluated through heart rate (HR) variability (HRV) indexes and postexercise HR recovery (HRR) indexes] with cardiorespiratory fitness and training load. We have measured cardiorespiratory fitness through peak oxygen consumption (Vo2 max) and estimated ...
Kaye Joey M - - 2006
Multiple system atrophy (MSA) and pure autonomic failure (PAF) represent distinct pathological models of autonomic failure in humans. We have investigated the neuroendocrine, behavioural and autonomic cardiovascular responses to the 35% CO2 challenge. Nine patients with MSA, nine with PAF and five control subjects received a single breath of 35% ...
Heffernan Kevin S - - 2006
BACKGROUND: The kinetics of parasympathetic reactivation after dynamic endurance exercise have been well elucidated. However, autonomic recovery of cardiac function after resistance exercise is not known. PURPOSE: The purpose of this study was to assess cardiac autonomic modulations during recovery from acute resistance exercise versus acute endurance exercise. METHODS: Electrocardiogram ...
Homma Shinji - - 2006
An electrogastrogram (EGG) recorded on the skin is believed to reflect the electrical activity of the gastrointestinal tract. In this study, linear correlations were calculated for the EGG spectral frequencies and the power ratios, changes in heart and respiratory rate before and during mirror drawing test (MDT) stress and after ...
Madden Kenneth M - - 2006
INTRODUCTION: Prior investigations in post-myocardial infarction and healthy elderly subjects have established that heart rate variability (HRV) predicts mortality. Predominantly cross-sectional studies have shown an association between endurance training and measures of HRV. In a randomized trial, this study sought to prospectively compare the effects of endurance and strength training ...
Casties J-F - - 2006
We investigated the time course of RR interval variability during exercise and subsequent 50 minutes of recovery in seven well-trained male cyclists who performed an exercise with 3 successive 8 min stages at 40 %, 70 % and 90 % of their maximal oxygen uptake. The goal of the study ...
Raczak Grzegorz - - 2006
INTRODUCTION: Moderate-intensity endurance training causes increased parasympathetic activity while very intensive (extreme) exercise loads may lead to persistently elevated sympathetic tone in champion class athletes preparing for competitions. Exercise training loads used by regional class sportsmen are usually somewhat less intensive. AIM: To assess the changes in autonomic nervous system ...
West John B - - 2006
It is a strange coincidence that the highest point on Earth is very close to the limit of human tolerance to hypoxia. The physiological changes that allow humans to reach these extreme altitudes involve enormous alterations of their normal state. It is useful to contrast this response with two others ...
Platisa Mirjana M - - 2006
The aim of this study was to examine the dependence of heart rate variability (HRV) measures on RR interval length and to find out relationships between linear and nonlinear measures. The spectral powers in very low (VLF), low (LF) and high (HF) frequency regions, short-term scaling exponent alpha(1) and sample ...
Ma Heather T - - 2006
Pulse transit time (PTT) has been reported correlated with heart rate (HR) and blood pressure (BP), however, the results are not consistent in different investigations. Towards a better understanding of the underlying mechanisms of the PTT changes, this study compares the power spectrum density of the variability in PTT with ...
Raj Satish R - - 2006
Postural tachycardia syndrome (POTS), characterized by orthostatic tachycardia in the absence of orthostatic hypotension, has been the focus of increasing clinical interest over the last 15 years 1. Patients with POTS complain of symptoms of tachycardia, exercise intolerance, lightheadedness, extreme fatigue, headache and mental clouding. Patients with POTS demonstrate a ...
Aysin Benhur - - 2006
Beat-to-beat changes in cardiac signals or heart rate variability (HRV) are controlled by the two branches of autonomic nervous system (ANS) in a very complex manner. Although traditional HRV (tHRV) analysis has shown to provide information on cardiac ANS control, it often fails to isolate the effect of two branches ...
Khanna Gulshan Lal GL Human Performance Laboratory, Sports Authority of India , J. N. S., New Delhi, - - 2006
The present study was conducted to study the morphological, physiological and biochemical characteristics of Indian National boxers as well as to assess the cardiovascular adaptation to graded exercise and actual boxing round. Two different studies were conducted. In the first study [N = 60, (junior boxers below-19 yrs, n = ...
Alipour Mohsen M Department of Physiology, Zanjan University of Medical Sciences , Zanjan, - - 2006
Despite the knowledge on the antiatherogenic effects of exercise, the mechanism by which exercise reduces atherogenic risk remains unknown. In this study, we investigated the hypothesis that chronic exercise-induced oxidative stress may increase plasma total antioxidant capacity and antioxidant defense in the red cells. For 8 weeks, 60 male Dutch ...
Ergün Metin M Department of Sports Medicine, Ege University School of Medicine Izmir, - - 2006
As studying with population carrying no classical cardiovascular risk factors seems to be an advantage in isolating effects of regular exercise on endothelial functions, inflammatory and thrombotic activity; the present study was designed to evaluate the clear effects of long-term regular exercise in middle-aged, healthy men. A total of 32 ...
Damgaard Morten - - 2006
Patients with untreated heart failure (HF) exhibit a blunted hemodynamic and neuroendocrine response to a high sodium intake, leading to excessive sodium and water retention. However, it is not known whether this is the case for patients with compensated HF receiving angiotensin-converting enzyme inhibitors and beta-adrenoreceptor blockers. Therefore, we determined ...
Kukielka Monica - - 2006
The present study investigated the effects of long-duration exercise on heart rate variability [as a marker of cardiac vagal tone (VT)]. Heart rate variability (time series analysis) was measured in mongrel dogs (n = 24) with healed myocardial infarctions during 1 h of submaximal exercise (treadmill running at 6.4 km/h ...
Cornolo J?r?my - - 2005
PURPOSE: Both training and chronic hypoxia act on the autonomic nervous system. Because trained Andean high-altitude natives could perform a high-altitude marathon (4220 m above sea level) in 02:27:23 h, we hypothesized that living in chronic hypoxia does not limit the training-induced benefits on the autonomic modulation of the heart. ...
Tarkiainen Tuula H - - 2005
Heart rate variability (HRV) is a widely used method to assess cardiac autonomic control. However, the reproducibility of especially short-term HRV has not been properly evaluated. Therefore, we assessed the stability of short-term HRV over a three to four month period. We had seven consecutive electrocardiographic (ECG) recordings from 89 ...
Cottin F - - 2005
RR intervals of ten elite trotting horses were recorded during an interval training session performed on track. This study examined two hypotheses. Firstly, like in humans, the hyperpnea combined with a decrease in cardiac autonomic control on heart rate during heavy exercise could result in a prevalence of high frequency ...
Gaul-Alácová Petra - - 2005
OBJECTIVES: The aim of the study was to determine the status of the autonomic nervous system (ANS) in anxiety disorder patients and to evaluate possible exercise intervention in order to improve the ANS and overall psychiatric status of patients. PATIENTS AND METHODS: The ANS function was monitored via means of ...
Billman George E - - 2006
Low heart rate variability (HRV) is associated with an increased susceptibility to ventricular fibrillation (VF). Exercise training can increase HRV (an index of cardiac vagal regulation) and could, thereby, decrease the risk for VF. To test this hypothesis, a 2-min coronary occlusion was made during the last min of a ...
Ichinose Masashi - - 2006
We investigated the time-dependent modulation of arterial baroreflex (ABR) control of muscle sympathetic nerve activity (MSNA) that occurs during isometric handgrip exercise (IHG). Thirteen healthy subjects performed a 3-min IHG at 30% maximal voluntary contraction, which was followed by a period of imposed postexercise muscle ischemia (PEMI). The ABR control ...
Topal Ergun - - 2006
OBJECTIVE: We sought to examine the effect of trimetazidine (TMZ) on heart rate variability (HRV), endothelin-1 (ET-1), NO, and anginal symptoms in patients with slow coronary artery flow (SCAF). METHODS: The 48 patients with SCAF (29 women and 19 men; mean age, 52 +/- 9 years) were included in the ...
Pichon Aurélien - - 2006
Interchangeability between fast Fourier transform (FFT) and autoregressive (AR) analysis was assessed on series of 256 R-R intervals recorded in 56 seated subjects and in 15 men performing an orthostatic test. Low- (LF) and high-frequency (HF) components were calculated and expressed both in absolute (square milliseconds) and normalized units (NU). ...
Ditor D S - - 2005
Four-month longitudinal within-subject exercise training study. Although body-weight supported treadmill training (BWSTT) has not shown promise as a means of improving ambulation in individuals with motor-complete spinal cord injury (SCI), it may still improve cardiovascular health and function in this population. The purpose of this study was to (i) investigate ...
Houtveen Jan H - - 2005
The extent to which variation in posture and respiration can confound pre-ejection period and respiratory sinus arrhythmia (RSA) as indices of cardiac sympatho-vagal activity was examined. Within-subjects changes in these measures were assessed in 36 subjects during different postures and (paced) respiratory frequencies. Changes from supine to sitting to standing ...
Winsley R J - - 2005
Resting heart rate variability (HRV) profile was compared between sedentary and active females before, during, and after a 2-week overreaching protocol. Twenty currently active and 20 sedentary females were subdivided within their groups to either an experimental or control group. The active and sedentary experimental groups completed an overreaching protocol; ...
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