Search results for " Variability"
showing 10 items of 853 documents
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…
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…
Intermittent cooling during judo training in a warm/humid environment reduces autonomic and hormonal impact
2018
Carballeira, E, Morales, J, Fukuda, DH, Granada, ML, Carratalá-Deval, V, López Díaz de Durana, A, and Stout, JR. Intermittent cooling during Judo training in a warm/humid environment reduces autonomic and hormonal impact. J Strength Cond Res 33(8): 2241-2250, 2019-The purpose of this study was to identify the effects of superficial cooling on physiological responses while training in a warm, humid environment during an international Judo training camp. Sixteen judokas (8 women and 8 men) participated in the experiment. Four high-level women and 4 men were randomly assigned to wear a cooling vest (vest group [VG]) during the recovery periods within a training session (i.e., 8 bouts of 5-minu…
Instantaneous Transfer Entropy for the Study of Cardiovascular and Cardio-Respiratory Nonstationary Dynamics
2017
Objective: Measures of transfer entropy (TE) quantify the direction and strength of coupling between two complex systems. Standard approaches assume stationarity of the observations, and therefore are unable to track time-varying changes in nonlinear information transfer with high temporal resolution. In this study, we aim to define and validate novel instantaneous measures of TE to provide an improved assessment of complex nonstationary cardiorespiratory interactions. Methods: We here propose a novel instantaneous point-process TE (ipTE) and validate its assessment as applied to cardiovascular and cardiorespiratory dynamics. In particular, heartbeat and respiratory dynamics are characteriz…
Single region of interest versus multislice T2* MRI approach for the quantification of hepatic iron overload.
2011
Purpose To evaluate the effectiveness of the single ROI approach for the detection of hepatic iron burden in thalassemia major (TM) patients in respect to a whole liver measurement. Materials and Methods Five transverse hepatic slices were acquired by a T2* gradient-echo sequence in 101 TM patients and 20 healthy subjects. The T2* value was calculated in a single region of interest (ROI) defined in the medium-hepatic slice. Moreover, the T2* value was extracted on each of the eight ROIs defined in the functionally independent segments. The mean hepatic T2* value was calculated. Results For patients, the mean T2* values over segments VII and VIII were significantly lower. This pattern was su…
Impact of HBV genotypes A and D genetic variability on infection evolution
2015
HBV is characterized by a high genetic variability, which is the basis of its classification into eight genotypes (A-H). HBV infection is associated with different outcomes, from self-limiting acute hepatitis to active chronic hepatitis, asymptomatic carriage, and occult infection. The aim of this study was to analyze the genetic variability of HBV genotypes A and D isolates from 79 cases of self-limiting acute hepatitis and chronic hepatitis, in order to identify HBV variants associated with resolution or chronicity of acute HBV infection. The entire preS-S sequence and a fragment of 346 bp of the preC-C region, containing Enhancer II and Basal Core Promoter sequences, were analyzed. A phy…