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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 30 (1993), S. 0 
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Laboratory stress testing is typically conducted while subjects are seated, whereas real-life stressors may often be encountered while standing. The present study of 20 healthy young men evaluated blood pressure and underlying hemodynamic adjustments to a standardized mental arithmetic task performed twice while seated and twice while standing. Blood pressure increased during mental arithmetic in both postures, but the underlying hemodynamic determinants of the pressor responses were different for the two postures. Augmented cardiac output was responsible for increasing blood pressure during seated task performance, whereas increased vascular resistance was the mechanism for the pressor response to the task performed while standing. Blood pressure and hemodynamic responses were reproducible subject characteristics for a given posture; test-retest correlations were significant for all cardiovascular measures. However, seated blood pressure responses were not significantly correlated with standing blood pressure responses. In contrast, significant between-posture correlations were found for cardiac output and vascular resistance responses. This preliminary evidence of postural stability of the hemodynamic determinants of blood pressure responses during stress is consistent with growing evidence that hemodynamic response tendencies are robust characteristics of reactivity. Ambulatory monitoring of hemodynamic response patterns during real-life stress may reveal more idiosyncratic profiles of stress reactivity than are displayed by blood pressure responses alone.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 27 (1990), S. 0 
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: This laboratory study was designed to address a number of interrelated issues regarding cardiovascular reactivity to psychological stress. One objective was to extend the previous research comparing cardiovascular responses during active versus passive coping, by comparing responses to two task conditions designed to be similar in all ways except the opportunity to make a response influencing the task's outcome. A second objective was to compare responses to two different passive film tasks, which differed in outcome uncertainty and the degree of vicarious active coping achieved through identification with the role portrayed by the actors. A third objective was to evaluate whether individuals are predisposed to exhibit a particular hemodynamic pattern underlying their blood pressure adjustments, independently of the task demands imposed. Ninety healthy young adult male subjects were tested in pairs on a series of tasks that included a competitive reaction-time task, an active as well as a passive phase of a team reaction-time task, and passive viewing of two film segments. The tasks demanding active coping responses tended to raise blood pressure due primarily to an increase in cardiac output, while vascular resistance fell. During passive coping demands cardiac output increased to a lesser extent, but vascular resistance also tended to increase, thereby raising blood pressure by their synergistic effects. However, these patterns were not typical of all participating subjects. On the basis of their cardiac output and vascular resistance responses to the competitive reaction-time task, one third of the subjects were categorized as being high myocardial reactors (n=30) and another third high vascular reactors (n=31). Post-hoc analyses of responses to the other tasks, based on these categorizations, indicated that the hemodynamic basis of reactivity is an individual characteristic only partially modified by coping demands. The active/passive coping dimension is discussed both conceptually and in relation to the role of stress in the etiology of hypertension.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 23 (1986), S. 0 
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: The relationships among a variety of cardiovascular and respiratory measures were examined in young college males subjected to a cold pressor task, reaction-time shock avoidance task, and three levels of graded exercise. As expected, the relationships between cardiovascular (e.g., heart rate and cardiac output) and respiratory (e.g., oxygen uptake and minute ventilation) variables were tightly linear when considering rest and exercise values. However, the range of individual cardiopulmonary responses during cold pressor and reaction time was considerable, often leading to disruptions in the cardiovascular/respiratory interactions. Analyses of extreme high and low ventilation reactors during both reaction time and cold pressor revealed that the excessive ventilation responders in cold pressor showed clear signs of hyperventilation. Increases in ventilation by the high reactors during reaction time were of smaller magnitude than during cold pressor, with potential hyperventilation much less clear. Increases in minute ventilation by reactors during the cold pressor task were primarily due to large increases in tidal volume, with only modest increases in respiratory rate. For reaction time, however, the increases in ventilation by reactive individuals stemmed from rate increases with tidal volume remaining essentially unchanged.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 20 (1983), S. 0 
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Two studies are reported in which heart rate and oxygen consumption were monitored in rats during behavioral adaptation to avoidance conditioning tasks. In the first study, the provision of information regarding potential shock delivery for one group of animals led to them exhibiting a tendency toward increased behavioral efficiency compared with a low information group. The metabolic appropriateness of heart rate was assessed on the basis of a linear regression equation fitted to habituation data. During conditioning, both groups displayed heart rates that exceeded the predictions of this equation and, contrary to expectations, the group provided with additional information tended to display the more elevated heart rates. However, an interpretation of these effects was confounded by group differences in ambulation rates. Experiment 2 set out to test a specific hypothesis suggested by the results of the first experiment: that levels of metabolically elevated heart rates are directly related to motor preparatory states. Data in support of this hypothesis are presented, followed by a general discussion of the relationship between behavioral states and cardiovascular function.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 20 (1983), S. 0 
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: Two groups of rats received food on variable-interval schedules during SD but not during SΔ periods. Food delivery was contingent on running for Experimental subjects but independent of behavior for Controls. Contrary to predictions based on the energy maximization principle, Controls did not develop a more energy-efficient behavioral adaptation than Experimentals. The contingency of food delivery influenced the SD/SΔ distributions of running (AMB) and oxygen consumption (OC) but not their overall rates. Overall OC and AMB rates appear to have been determined by the similar levels of food deprivation and rates of food delivery to which both groups were submitted. AMB was found to be a less conspicuous determinant of energy expenditure than the rate of food delivery which, it is argued, influenced OC by eliciting high-energy consumatory activities. Although significant positive correlations between variations of heart rate (HR) and OC were observed in both groups, the HR/OC correlation was significantly weaker in the Control than in the Experimental group. This result is discussed in terms of the effects of the reinforcement contingencies on cardio-somatic control.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: We report the first systematic study of hemodynamic responses to the Social Competence Interview, using the original Ewart protocol, which focuses attention on a persisting personal threat. Physiologic changes in 212 African American and Caucasian urban adolescents during the Social Competence Interview, mirror tracing, and reaction time tasks showed that the Social Competence Interview elicits a pronounced vasoconstrictive response pattern, with diminished cardiac activity, that is more typical of alert mental vigilance than of active coping. This pattern was observed in all race and gender subgroups. Results suggest that the Social Competence Interview may be a broadly useful procedure for investigating the role of threat-induced vigilance in cardiovascular and other diseases.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: In this study we examined test-retest stability of cardiovascular stress responses over a decade of the life span. Participants were 55 male college undergraduates. 19 years of age at initial testing, and 29 years of age at follow-up testing Stressors were a foot cold pressor and an aversive reaction time task. Cardiovascular measures included systolic and diastolic blood pressure, heart rate, and preejection period. For cold pressor, the magnitude and pattern of cardiovascular responses remained unchanged at the 10-year follow-up. For the reaction time task, the characteristic cardiovascular response patterns was preserved but with significant attenuation of magnitude. The present findings are consistent with previous observations of temporal stability but over a substantially longer test-retest interval. The long-term stability of stress responses is discussed in the context of stress test methodology, behavioral response demands, and maturation of the physiological systems involved in cardiovascular response expression.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: This study was designed to examine the hypothesis that certain behavioral demands may tend to trigger sympathetic mechanisms which result in metabolically excessive cardiac output elevations. Oxygen consumption and cardiac output adjustments during a contrived reaction-time shock-avoidance task were compared to a cold pressor test in healthy young male adults. The linear cardiac output/oxygen consumption relationship generated by performance on a graded exercise task was used to assess the metabolic appropriateness of cardiac output adjustments to the reaction-time task and cold pressor. The reaction-time task was generally found to evoke metabolically excessive increases in cardiac output, while cardiac output adjustments to cold pressor were more consistent with changes in metabolic demands. However, the tasks were associated with similar heart rate responses, with a significant attenuation in stroke volume during cold pressor accounting for the differential alterations in cardiac output. This finding suggests a limited reliability for heart rate as an index of cardiac performance. The effects of propranolol, which was employed to evaluate the role of sympathetic influences, indicated that beta-adrenergic mechanisms were responsible for mediating the cardiac output response to the reaction-time task, but only partially contributed to the cold pressor response. Post-hoc analyses of individual differences in cardiovascular reactivity to the reaction-time task suggest that, for hyperreactive individuals, the coping responses evoked by this task may lead to tissue overperfusion with oxygen, thereby providing a stimulus for autoregulatory vascular reflexes which may be associated with the etiology of hypertensive disease.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 29 (1992), S. 0 
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: The comprehensive assessment of cardiac function using impedance cardiography has led to increasingly widespread use of the technique in psychophysiology. Disposable adhesive band electrodes have been the most widely used electrode type, but spot electrode configurations present attractive alternatives in terms of convenience and subject comfort. The present study was designed to evaluate whether one such spot electrode configuration yielded the same information as the more standard band electrodes for cardiac output and systolic time interval measurement. Male and female healthy adult subjects (N=20) were tested. Comparisons between spot and band electrodes were made for the absolute magnitude of cardiac output and systolic time intervals, as well as for responses to the highly reproducible effects of bicycle exercise. Consistent with previous findings, systolic time interval measurements were unaffected by electrode type. However, for cardiac output measurements, differences between spot and band electrode measurements were found. Under resting conditions, the absolute magnitudes of cardiac output values measured using spot electrodes were smaller than for band electrodes. Subtle, yet significant differences were also found for cardiac output responses to exercise, with spot electrodes indicating greater increases in cardiac output than band electrodes. At the same time, anticipated gender differences found for cardiac output at rest and in response to exercise were unaffected by electrode type. Overall, these findings suggest that when comparing the results of studies that have utilized different impedance electrode types, it would be prudent to remain alert to the possibility of confounding influences.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: The primary purpose of this study was to examine the covariation of cardiac output and forearm blood flow during reaction time, mental arithmetic, and cold pressor tasks. Cardiac output was indexed using impedance cardiography, whereas impedance venous occlusion plethysmography was used lo index forearm blood flow. Cardiac output increased significantly over resting values in all three tasks, hut the pattern of these increases differed. Large heart rate increases during mental arithmetic and cold pressor tasks more than offset stroke volume decreases; the increases in the reaction time task were due to relatively smaller heart rate increases with stroke volume augmentation. For forearm blood flow, all task levels were higher than resting levels, but only mental arithmetic levels were statistically higher. The correlation between cardiac output and forearm blood flow change was significant for the reaction time task, but not for the mental arithmetic or cold pressor tasks.
    Type of Medium: Electronic Resource
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