Search results for "variability"
showing 10 items of 904 documents
Cytochrome P450 2E1 variable number tandem repeat polymorphisms and health risks: A genotype-phenotype study in cancers associated with drinking and/…
2012
Cytochrome P450 2E1 (CYP2E1) is one of the main enzymes involved in the oxidation of ethanol and in the transformation of a number of potentially dangerous compounds. It has various polymorphic sites, one of which is a variable number tandem repeat (VNTR) polymorphism previously described in the 5'-flanking region. The aim of this study was to investigate the genotype-phenotype association between CYP2E1 VNTR polymorphisms and risky health habits in healthy subjects and to analyze the associations between these polymorphisms with drinking- and/or smoking-related cancers. We analyzed 166 healthy subjects by genotyping for the CYP2E1 VNTR polymorphism associated with drinking and/or smoking h…
Retinal vessel analysis and heart rate variability
2014
Heart rate variability (HRV) is used to index the vegetative nervous system and is linked with cardiovascular and nervous diseases [1]. Funduscopic assessment of the retinal vasculature can be utilized to evaluate the health status of microcirculation and to assess the predisposition of major vascular diseases [2]. The purpose of this study was, for the first time, to examine the influence of HRV on microcirculation as an early marker of cardiovascular alteration. The study population was comprised of apparently healthy employees of a high-tech company in Germany. The participants spanned the entire age of the work force (18–65 years) and all levels of socioeconomic status. A total of 292 s…
The time line of threat processing and vagal withdrawal in response to a self-threatening stressor in cognitive avoidant copers: evidence for vigilan…
2010
Using a spatial cueing paradigm with emotional and neutral facial expressions as cues, we examined early and late patterns of information processing in cognitive avoidant coping (CAV). Participants were required to detect a target that appeared either in the same location as the cue (valid) or in a different location (invalid). Cue–target onset asynchrony (CTOA) was manipulated to be short (250 ms) or long (750 ms). CAV was associated with early facilitation and faster disengagement from angry faces. No effects were found for happy or neutral faces. After completing the spatial cueing task, participants prepared and delivered a public speech and heart rate variability (HRV) was recorded. Di…
Sex differences in autonomic response and situational appraisal of a competitive situation in young adults.
2017
Competition is a social stressor capable of eliciting physiological responses modulated by the outcome. The main objective of this study was to analyze the psychophysiological changes associated with competition and its outcome in men and women, taking into account the role of situational appraisal. To this end, 112 young people (46 men and 66 women) participated in a laboratory task in a competitive or non-competitive condition, while Blood Pressure (BP), Heart Rate Variability (HRV), and Skin Conductance (SC) responses were measured. Our results indicate that competition elicits higher systolic blood pressure (SBP) than a non-competitive task; in addition, winners presented a greater R-R …
The Use of Heart Rate Variability in Assessing Precompetitive Stress in High-Standard Judo Athletes
2012
The objective of this study is to examine the sensitivity to and changes in heart rate variability (HRV) in stressful situations before judo competitions and to observe the differences among judo athletes according to their competitive standards in both official and unofficial competitions. 24 (10 male and 14 female) national- and international-standard athletes were evaluated. Each participant answered the Revised Competitive State Anxiety Inventory (CSAI-2R) and their HRV was recorded both during an official and unofficial competition. The MANOVA showed significant main effects of the athlete's standard and the type of competition in CSAI-2R, in HRV time domain, in HRV frequency domain an…
Quantifying foot placement variability and dynamic stability of movement to assess control mechanisms during forward and lateral running
2015
Research has indicated that human walking is more unstable in the secondary, rather than primary plane of progression. However, the mechanisms of controlling dynamic stability in different planes of progression during running remain unknown. The aim of this study was to compare variability (standard deviation and coefficient of variation) and dynamic stability (sample entropy and local divergence exponent) in anterior–posterior and medio-lateral directions in forward and lateral running patterns. For this purpose, fifteen healthy, male participants ran in a forward and lateral direction on a treadmill at their preferred running speeds. Coordinate data of passive reflective markers attached …
Comparison of Methods for the Assessment of Nonlinearity in Short-Term Heart Rate Variability under different Physiopathological States
2019
Despite the widespread diffusion of nonlinear methods for heart rate variability (HRV) analysis, the presence and the extent to which nonlinear dynamics contribute to short-term HRV are still controversial. This work aims at testing the hypothesis that different types of nonlinearity can be observed in HRV depending on the method adopted and on the physiopathological state. Two entropy-based measures of time series complexity (normalized complexity index, NCI) and regularity (information storage, IS), and a measure quantifying deviations from linear correlations in a time series (Gaussian linear contrast, GLC), are applied to short HRV recordings obtained in young (Y) and old (O) healthy su…
Cardiovascular control and time domain granger causality: Insights from selective autonomic blockade
2013
We studied causal relations among heart period (HP), systolic arterial pressure (SAP) and respiration (R) according to the definition of Granger causality in the time domain. Autonomic pharmacological challenges were used to alter the complexity of cardiovascular control. Atropine (AT), propranolol and clonidine (CL) were administered to block muscarinic receptors, β-adrenergic receptors and centrally sympathetic outflow, respectively. We found that: (i) at baseline, HP and SAP interacted in a closed loop with a dominant causal direction from HP to SAP; (ii) pharmacological blockades did not alter the bidirectional closed-loop interactions between HP and SAP, but AT reduced the dominance of…
Emotional and autonomic dysregulation in abstinent alcoholic men: An idiosyncratic profile?
2019
Men who misuse alcohol tend to experience negative affect, which may entail difficulties in regulating emotions to cope effectively with stressful or anxiety-provoking situations, thus increasing the risk of alcohol relapse. This dysphoric state has been associated with alexithymia, which compromises an individual's abilities to acknowledge, recognize, and regulate emotional states. A physiological correlate of emotional regulation is autonomic flexibility, as shown by emotional dysregulation in men who misuse alcohol being correlated with reduced parasympathetic activation to control heart rate variability during stress and/or conflict situations. Hence, the main aim of this study was to i…
A new heart rate variability-based method for the estimation of oxygen consumption without individual laboratory calibration: Application example on …
2008
Traditionally, the estimation of oxygen consumption (VO2) at work using heart rate (HR) has required the determination of individual HR/VO2 calibration curves in a separate exercise test in a laboratory (VO2-TRAD). Recently, a new neural network-, and heart rate variability-based method has been developed (Firstbeat PRO heartbeat analysis software) for the estimation of VO2 without individual calibration (VO2-HRV). In the present study, the VO2-values by the VO2-HRV were compared with the values by VO2-TRAD in 22 postal workers. Within individuals the correlation between the two methods was high (range 0.80-0.99). The VO2-TRAD gave higher values of VO2 compared to VO2-HRV (19%) especially d…