Aerobic Fitness Affects Cardiovascular and Catecholamine Responses to Stressors

Subjects of varying degrees of aerobic fitness were subjected to four laboratory stressors in a test of the hypothesis that aerobic fitness is associated with decreased responsiveness to stressors other than exercise. Blood pressure, heart rate, norepinephrine, epinephrine, and psychological responses to a film of industrial accidents (passive psychological stressor), the Stroop word color task (active psychological stressor), the cold pressor test (passive physical stressor), and running to exhaustion on a treadmill (active physical stressor) were measured. Baseline systolic blood pressure and relative diastolic responses to the film, Stroop task, and exercise were smaller in fit subjects over 40 than in less fit subjects of the same age group. Heart rates were lower in fit subjects at most times, except during and after maximal exercise. Norepinephrine was lower after 9 min of exercise in fit subjects, but was much higher at exhaustion, after these subjects had accomplished more work. Norepinephrine levels fell rapidly and were not different among groups 3 and 10 min after exercise. There was no preferential generalization of the “fitness effect” to the active psychological task.     

Effects of aerobic and nonaerobic exercise on anxiety,absenteeism, and job satisfaction

The effects of aerobic and nonaerobic exercise on employee state and trait anxiety levels, absenteeism, job satisfaction, and resting heart rate were investigated within a worksite setting. Results indicated that aerobic subjects significantly reduced their state anxiety levels over a single exercise session. Post-exercise state anxiety decreased over the 8 weeks for both groups. Aerobic subjects who were not previous exercisers decreased their trait anxiety. No changes in job satisfaction, absenteeism, or resting heart rate were evident. These results support past findings that concluded that aerobic exercise is superior to nonaerobic exercise for anxiety reduction. Tentative evidence was found to oppose the hypothesis that cardiovascular conditioning is the mechanism responsible for the psychological benefits because no significant cardiovascular changes occurred.     

Aerobic Fitness and Opioidergic Inhibition of Cardiovascular Stress Reactivity

The role of endogenous opioids in aerobic fitness-induced decrements in cardiovascular stress reactivity was examined by comparing the effects of opioid antagonism with naltrexone on responses to stress in young adults with high versus low levels of aerobic fitness. Two hundred forty subjects were given an activity questionnaire and males with the highest (Fit) and lowest (Nonfit) aerobic activity profiles were recruited for maximal oxygen consumption (VO2max) treadmill testing and psychological stress testing (final sample N = 28). Heart rate and blood pressures were measured during performance on a computer-controlled arithmetic task after pretreatment with either naltrexone (Trexan, DuPont) or a placebo. During placebo challenges, Fit subjects, compared with Nonfit, showed lower heart rate reactivity during stress and lower mean arterial blood pressures immediately before and during recovery from stress. Naltrexone eliminated these reactivity differences by increasing heart rate reactivity and raising mean arterial blood pressure in Fit subjects. These data suggest that aerobic fitness is associated with enhanced opioidergic inhibition of circulatory stress reactivity. Opioidergic modulatory effects on stress reactivity may comprise an important mechanism in fitness-associated risk reduction for cardiovascular disease.     

Psychophysiological responses to the Stroop Task after a maximal cycle ergometry in elite sportsmen and physically active subjects.

Physical fitness moderates the psychophysiological responses to stress. This study attempts to determine whether the degree of fitness could affect the response to physical and psychological stress after comparing two groups of men with good physical fitness. Saliva samples from 18 elite sportsmen, and 11 physically active subjects were collected to determine hormonal levels after carrying out a maximal cycle ergometry. Heart rate and skin conductance level were continuously recorded before, during, and after a modified version of the Stroop Color-Word Task. With similar scores in trait anxiety and mood, elite sportsmen had lower basal salivary testosterone, testosterone/cortisol ratio, and HR before an ergometric session than physically active subjects, but no differences were found in salivary cortisol and blood pressure. Salivary testosterone and cortisol responses were lower and testosterone/cortisol ratio responses higher in elite sportsmen. During the Stroop Task, elite subjects showed lower heart rate and skin conductance level over the entire measurement period, and greater heart rate recovery with respect to the baseline values than physically active subjects. The effects of two standardised laboratory stressors on a set of psychophysiological variables were different when elite sportsmen and physically active subjects were compared.     

Existing and Training Induced Differences in Aerobic Fitness: Their Relationship to Physiological Response Patterns During Different Types of Stress

Aerobic fitness has been associated with various desirable psychological and physiological characteristies. Recently, attenuation of physiological reactivity during stressful situations was added to this list, although comparison of the stress responses of sportsmen and sedentary subjects has yielded equivocal results. The present study examined cardiovascular patterns rather than single variables, and tried to clarify these matters. Tasks were used that were known to increase blood pressure through different combinations of changes in cardiac output and vascular resistance. Autonomic nervous system dynamics underlying these response patterns were studied using preejection period as an index of β-adrenergic activity, and respiratory sinus arrhythmia as an index of vagal activity. Pre-existing differences in aerobic fitness in a sample of sedentary subjects were related to their responses during the stressful tasks and the recovery periods afterwards. This approach prevented confounding of the relationship between fitness and stress-reactivity with the psychological effects of regular exercise. Furthermore, it excluded the bias in psychological makeup that is introduced when subjects spontaneously engaged in sports are compared to non-exercising persons. To rule out a third (hereditary?) factor underlying both stress-reactivity and fitness, physiological responses before and after a seven-week training program were compared to those of subjects in a waiting list control group. Substantial individual differences in aerobic fitness were found in spite of the fact that all subjects reported low levels of habitual activity. During two active coping tasks, diastolic blood pressure reactivity and vagal withdrawal were negatively related to these pre-existing differences in fitness. No such relation was seen during a cold pressor test or during recovery from the tasks. Neither β-adrenergic cardiac reactivity nor heart rate responses were related to fitness, but the absolute heart rate during the tasks was lower in the more fit subjects. Seven weeks of training were not effective in changing either reactivity or recovery of any of the variables. The discrepancy between cross-sectional and longitudinal results in the present study suggests that training of longer duration is necessary to induce the psychological or physiological changes underlying reduced reactivity. The latter may include changes in cardiac vagal/sympathetic balance or in adrenoceptor sensitivity. Alternatively, both psychological and physiological determinants of stress-reactivity may be related to aerobic fitness at a dispositional level.     

Association of Aerobic Fitness with Pulse Rate and Subjective Responses to Psychological Stress

Ten high fit and 10 low fit subjects first sat quietly during a baseline period and then participated in a mildly stressful task (recall of digits backwards). Pulse rates and levels of subjective arousal were assessed during the baseline period and during the task performance period. Initial analyses indicated that task performance resulted in general increases in pulse rates, subjective cognitive arousal, and subjective somatic arousal. More importantly, it was found that high fit subjects evinced a smaller pulse rate increase in response to stress than did low fit subjects, but the high and low fit subjects did not differ in their subjective responses to stress. These results are consistent with a growing body of research which indicates that a high level of aerobic fitness is associated with reduced physiological reactivity to psychological stress.     

Serum lipids, neuroendocrine and cardiovascular responses to stress in healthy Type A men.

This study examined the relationship between serum lipid activity in healthy Type A men and cardiovascular and neuroendocrine responses to a behavioral stressor, mental arithmetic. Assessment of blood lipids included measures of total cholesterol (TC), low density lipoprotein cholesterol (LDLC), high density lipoprotein cholesterol (HDLC), and serum triglycerides. Cardiovascular (blood pressure and heart rate) and neuroendocrine (epinephrine, norepinephrine and cortisol) responses were recorded before (rest), during (stress) and after (recovery) the mental arithmetic test. Diastolic blood pressure, mean arterial pressure and, to a lesser extent, systolic blood pressure levels at rest, during stress, and at recovery correlated positively with TC levels. In addition, both diastolic and mean arterial pressure were positively correlated with the ratio of TC to HDLC and with triglycerides during stress and recovery. Heart rate did not correlate with any lipid measure. Cardiovascular stress-reactivity calculated as change from rest to stress did not correlate significantly with any lipid measure. Plasma norepinephrine during stress correlated positively with triglycerides; a similar trend was observed for the TC/HDLC ratio. Plasma cortisol at rest and during stress correlated positively with the TC/HDLC ratio and serum triglycerides, and negatively with HDLC. Plasma norepinephrine reactivity calculated as change from rest to stress correlated negatively with HDLC and positively with triglycerides. In addition, cortisol reactivity was positively correlated with triglycerides. It is suggested that the mechanisms mediating Type A behavior and coronary heart disease may include increased cardiovascular and neuroendocrine responses as well as unfavorable lipid profiles.     

Aerobic Fitness and the Cardiovascular Response to Stress

The observation that aerobically fit persons react to physical load with a smaller sympathetic response than do less fit subjects suggests that their response to psychological stress might also be reduced. The evidence for this, however, is far from consistent. It was argued that this inconsistency might be due to the incomplete measurement of the response system involved. In the present experiment two groups, which differed strongly in maximal aerobic power, were compared with respect to their cardiovascular response to a laboratory stressor. In addition to the traditional heart rate and blood pressure measurements, pre-ejection period, cardiac output, and peripheral resistance were assessed. Since only the part of the stress response that is not accounted for by metabolic needs might have pathological significance, the so-called "additional" responses were also measured. Fitness was shown to be associated with smaller sympathetic effects on both heart and vessels. The decrement in pre-ejection period and the heart rate response were smaller in the high fit group. The total peripheral resistance and diastolic blood pressure responses pointed to a much stronger vascular reactivity in the low fit group. Unexpectedly cardiac output did not increase during stress. The strong heart rate response in the low fit group was compensated by a reduction in stroke volume, which probably originated in an increased peripheral resistance. The largest discrepancy between the effects of sympathetic activation during stress and exercise occurred in the vessels, as demonstrated by the large "additional" response in total peripheral resistance during stress. The data point to the often neglected role of vascular processes in experiments of this kind. Furthermore, it seems necessary to take the effect of fitness into account when comparing subjects with respect to their cardiovascular stress response.     

Effects of Seasonal Differences in Testosterone and Cortisol Levels on Pain Responses Under Resting and Anxiety Conditions

Purpose

This study investigated whether hormones and pain perception are associated with exam anxiety, and also whether exam anxiety is affected by seasonal differences in testosterone and cortisol levels.

Materials and Methods

Forty-six healthy males were recruited from a medical college. Anxiety was induced by having participants perform the Objective Structured Clinical Examination. Pressure was applied to the participants to induce pain. Pain thresholds, pain ratings, anxiety ratings, blood pressure, heart rate, salivary testosterone and cortisol levels were measured under resting and anxiety conditions in the spring and summer. Data were collected from 46 participants during the spring (n=25) and summer (n=21).

Results

Pain thresholds and testosterone levels were significantly lower under anxiety than at rest for all participants (n=46), while cortisol levels, pain ratings, and anxiety ratings were significantly higher under anxiety than at rest. In the spring (n=25), testosterone levels were significantly higher at rest than under anxiety, while there was no difference in cortisol levels between resting and anxiety conditions. In the summer (n=21), cortisol levels were significantly higher under anxiety than at rest, while there was no difference in testosterone levels between resting and anxiety conditions. There were no significant seasonal differences in pain and anxiety ratings and pain threshold.

Conclusion

These results indicate that seasonal differences in testosterone and cortisol levels under anxiety and at rest may affect pain responses. These results also suggest that acute clinical pain may be relieved by managing anxiety that is related to a decrease of testosterone in spring and a large increase of cortisol in summer.     

Concurrent levels of maternal salivary cortisol are unrelated to self-reported psychological measures in low-risk pregnant women

Associations between salivary cortisol and maternal psychological distress and well-being were examined prospectively on 112 women with normally progressing, singleton pregnancies between 24 and 38 weeks gestation. At each of 5 visits, conducted in 3-week intervals, women provided a saliva sample and completed questionnaires measuring trait anxiety, depressive symptoms, pregnancy-specific hassles and uplifts, and psychological well-being. Maternal salivary cortisol was unrelated to psychological measures with the exception of minor associations detected with measures of anxiety and depressive symptoms between 30 and 32 weeks only. Findings indicate that self-reported maternal psychological distress and well-being are not associated with significant variation in maternal salivary cortisol levels during the second half of gestation. This suggests that studies that measure psychological factors in pregnancy but do not measure maternal cortisol should exercise caution in assuming activation of the maternal hypothalamic–pituitary–adrenal axis is the mechanism through which maternal psychological factors are transduced to the fetus.     

The relationship between psychological and physiological measures of anxiety

The responses of 6 representative physiological parameters frequently assumed to be measures of anxiety along with a set of 4 psychological tests for measuring anxiety were obtained under naturalistic conditions from 25 patients hospitalized with a first myocardial infarction. A canonical correlational analysis failed to show any relationship between anxiety as assessed by the Taylor Manifest Anxiety Scale, Mood Adjective Check List, State-Trait Anxiety Inventory and Multiple Affect Adjective Check List psychological tests, and anxiety as assessed by the physiological indices of heart rate, systolic and diastolic blood pressures, epinephrine, norepinephrine and VMA. The intercorrelation matrix revealed a significant positive pattern of relationships among all 4 psychological tests, a non-significant, positive pattern of relationships among the physiological indices, and a non-significant, negative pattern of relationships between the psychological and physiological measures. The absence of mood-specific physiological measures for anxiety, as measured by the psychological tests, supports previous theory and investigation and points to the inadvisability of assuming that studies on anxiety that use diverse physiological and psychological measures yield results that may be compared as though they were assessing a common mood.     

Aerobic Fitness, Physical Activity, and Psychophysiological Reactions to Mental Tasks

The association between aerobic fitness, exercise, and psychophysiological reactivity was assessed in cross-sectional and prospective analyses. Seventy-five healthy but sedentary adults carried out a sub-maximal exercise test and easy and difficult problem solving tasks. Blood pressure, heart rate, skin conductance level, respiration rate, tidal volume, and oxygen consumption were monitored and additional heart rate was also computed. Differences between relatively fit and unfit individuals were found in respiration rate during tasks and in skin conductance level during post-task recovery periods, with a tendency toward diminished heart rate reactivity in fitter people. Subjects were subsequently allocated to four conditions: high intensity aerobic training, moderate intensity aerobic training, an undemanding strength and flexibility program (designed as an attention-placebo condition), and waiting list control. Training programs were conducted over a 10-week period, and were followed by a second laboratory session. Appropriate changes in aerobic performance over the training period were observed in the 12-min run/walk test. There were no important modifications in psychophysiological stress reactions associated with the different experimental conditions. These results are discussed in relation to the literature concerning the effects of fitness and physical activity on physiological response patterns.     

Interrelationship of plasma cortisol and other activation indices during EMG biofeedback training

Plasma cortisol, cephalic electromyography (EMG), heart rate, fingertip vasoconstriction/dilation, respiration rate, self-reported anxiety, and target symptom severity were monitored in 24 human outpatients who volunteered to undergo the novel experience of an eight-session EMG biofeedback-based relaxation training program. Acute cortisol levels were generally found to be positively related to heart rate, degree of vasoconstriction, and self-reported anxiety but independent of cephalic EMG level and respiration rate. For the 12 participants above the median in initial trait anxiety, the mean reductions in cortisol were 22, 19, and 31% (relative to baseline) at the fourth, eighth, and 1-month follow-up sessions, respectively. Although there was some indication of the presence of a centrally integrated state of lowered neurophysiological arousal, the multiple dependent measures suggest that relaxation in this situation is not necessarily a simple unitary physiological and psychological event.The authors wish to thank David Greenwald and Daniel Klaus for assistance in collecting the data reported here. This research was partially supported by an award from the Roche Psychiatric Service Foundation, Stress Grants Program, and NIH Grant NS04095.     

Children's heart rate variability as stress indicator: Association with reported stress and cortisol

Stress is a complex phenomenon coordinated by two main neural systems: the hypothalamic–pituitary–adrenal system with cortisol as classical stress biomarker and the autonomic nervous system with heart rate variability (HRV) as recently suggested stress marker. To test low HRV (5 minute measurements) as stress indicator in young children (5-10y), associations with self-reported chronic stress aspects (events, emotions and problems) (N = 334) and salivary cortisol (N = 293) were performed. Peer problems, anger, anxiety and sadness were associated with lower root mean square of successive differences (RMSSD) and high frequency power (i.e. lower parasympathetic activity). Anxiety and anger were also related to a higher low frequency to high frequency ratio. Using multilevel modelling, higher cortisol levels, a larger cortisol awakening response and steeper diurnal decline were also associated with these HRV patterns of lower parasympathetic activity. Conclusion: Low HRV (lower parasympathetic activity) might serve as stress indicator in children.     

Aerobic exercise training and cardiovascular reactivity to psychological stress in sedentary young normotensive men and women

Forty-five (22 women) sedentary young (18-30 years old) nonsmoking normotensive volunteers engaged in either 6 weeks of aerobic training (AT), weight training (WT), or a no-treatment (NT) condition to determine whether AT lowers systolic (SBP) and diastolic (DBP) blood pressure, heart rate (HR), and rate-pressure product (RPP) during rest, psychological stress, and recovery periods. Estimated VO(2)max increased for the AT (32.1+/-1.1 to 38.4+/-1.0 ml.kg(-1).min(-1)). A smaller increase for the WT (30.5+/-1.1 to 33.8+/-1.0) was likely due to increased leg strength, and VO(2)max did not change for the NT (32.5+/-1.1 to 32.9+/-1.0). Heart rate and RPP levels were lower during psychological stress and recovery after training for AT relative to the WT and NT. Overall SBP was also lower in the AT relative to the NT but not the WT. In conclusion, aerobic training lowered cardiovascular activity levels during psychological stress and recovery in healthy young adults, implying a protective role against age-related increases in coronary heart disease for individuals who adopt aerobic exercise early in life and maintain the behavior across the life span.     

Caffeine affects cardiovascular and neuroendocrine activation at work and home

OBJECTIVE: This study investigated the effects of moderate doses of caffeine on ambulatory blood pressure and heart rate, urinary excretion of epinephrine, norepinephrine, and cortisol, and subjective measures of stress during normal activities at work and at home in the evening. METHODS: Healthy, nonsmoking, habitual coffee drinkers (N = 47) participated in 3 days of ambulatory study. After a day of ad lib caffeine consumption, caffeine (500 mg) and placebo were administered double-blind in counter-balanced order on separate workdays. Ambulatory blood pressure and heart rate were monitored from the start of the workday until bedtime. Urinary excretion of catecholamines and cortisol was assessed during the workday and evening. RESULTS: Caffeine administration significantly raised average ambulatory blood pressure during the workday and evening by 4/3 mm Hg and reduced average heart rate by 2 bpm. Caffeine also increased by 32% the levels of free epinephrine excreted during the workday and the evening. In addition, caffeine amplified the increases in blood pressure and heart rate associated with higher levels of self-reported stress during the activities of the day. Effects were undiminished through the evening until bedtime. CONCLUSIONS: Caffeine has significant hemodynamic and humoral effects in habitual coffee drinkers that persist for many hours during the activities of everyday life. Furthermore, caffeine may exaggerate sympathetic adrenal-medullary responses to the stressful events of normal daily life. Repeated daily blood pressure elevations and increases in stress reactivity caused by caffeine consumption could contribute to an increased risk of coronary heart disease in the adult population.     

Maternal trait anxiety, emotional distress, and salivary cortisol in pregnancy

Animal models suggest that stress-induced hormonal changes in the mother during pregnancy lead to enduring changes in the fetus and empirical links between prenatal maternal stress and negative child development have been discerned repeatedly in human studies. But the role of heritable personality traits has received little attention in the latter work. The goal of the current study was to investigate the relationship between maternal personality, psychological measures of maternal distress and maternal salivary cortisol during pregnancy. Maternal reports of personality (16 PF) and stress-related psychological measures (depression, pregnancy-related anxiety, perceived stress, negative life events) as well as salivary cortisol samples of 66 healthy pregnant women were collected in early and late pregnancy. Maternal trait anxiety proved related to all stress-related psychological measures and high anxiety predicted low baseline cortisol awakening levels in early pregnancy. Maternal trait anxiety is related to both psychological and biological stress measures during pregnancy.     

Phasic Cardiac Reactivity to Psychological Stress as a Function of Aerobic Fitness Level

Cardiovascular adjustments to physical exertion are known to be affected by aerobic fitness level. This raises the possibility that the cardiovascular responses associated with psychological stress may also be related to aerobic fitness. This study was undertaken to determine if phasic cardiac reactivity to stress would be affected by aerobic fitness level, and to make inferences regarding the autonomic mechanisms which might mediate such an effect. Twenty-four males were given a standard physical fitness test and then divided into high and low aerobic fitness level groups. Within two weeks of this assessment, the heart rate and electrocardiographic T-wave amplitude responses of these subjects were monitored during the performance of hard and easy versions of a mental arithmetic task. Analysis of the heart rate data revealed no aerobic fitness level effect. There was, however, greater T-wave amplitude attenuation in the low as compared to the high aerobic fitness level group on hard trials. This pattern of results suggests that psychologically-elicited sympathetic cardiac reactivity is reduced by enhanced aerobic fitness level.     

Oxytocin and cortisol in romantically unattached young adults: associations with bonding and psychological distress

Despite extensive research on the involvement of oxytocin (OT) in mammalian bonding, less is known about its role in human social affiliation across the life cycle. Forty-five romantically unattached young adults participated. Plasma oxytocin and salivary cortisol were assessed using enzyme immuno-assay, and self-report measures of bonding, attachment, anxiety, and depression were collected. Oxytocin was associated with bonding to own parents and inversely related to psychological distress, particularly depressive symptoms. Cortisol was related to attachment anxiety. Regression analysis indicated that the adult's representations of bonding to parents predicted OT levels above and beyond cortisol, psychological distress, and attachment. Findings are consistent with antistress models of oxytocin and suggest that oxytocin may play a role in bonding-related cognitions across the life span.     

The effect of stress on salivary cortisol in panic disorder patients.

BACKGROUND: Various findings suggest the possibility of an abnormal cortisol response to CRH in panic disorder patients, which raises the question of whether such patients might also produce an abnormal cortisol response to stress. The purpose of the present study was to use salivary cortisol measurement in assessing differences in response to novelty/mild stress situations between panic disorder subjects and controls. METHODS: Subjects were recruited by means of posters and subsequently screened for suitability as controls or panic subjects. Twenty-four panic disorder (PD) sufferers and 15 panic-free control subjects were tested on a range of psychometric and physiological measures, at both the start and the end of the experiment. Subjects were tested at the beginning for state anxiety, salivary cortisol, heart rate, and blood pressure, and these tests were repeated at the end of the session (which had been designed to promote reassurance). RESULTS: The state anxiety scores (STAI) showed a reduction in anxiety level over the test period, and there was a corresponding fall in both blood pressure and heart rate for both groups. Cortisol levels also fell over the course of the interview in the control group, but in the PD group cortisol levels showed no such reduction. In addition, there was a significant difference in the levels of cortisol at the start of the session between the two groups (PD group lower). CONCLUSIONS: These data indicate a possible alteration in cortisol responsiveness to stress/novelty situations in PD subjects. This was considered to be consistent with previous suggestions of HPA axis dysregulation in PD patients, although our research indicates unresponsiveness rather than responsiveness to be a factor to be considered for future investigation. CLINICAL IMPLICATIONS: Our results suggest that not all subjects suffering PD may benefit from stress reduction therapies as a first choice of treatment for their panic attacks. The existence of nocturnal panic attacks (considering sleep as a combination of mental and physical relaxation), in the absence of nightmares, as well as the induction of panic attacks during relaxation support this view. LIMITATIONS OF THE STUDY: Apart from the difficulty in accessing sufficient symptomatic subjects, the induction of higher levels of stress could be useful for confirmation of these results. However, this requires specialist support in case of subjects developing panic attacks during the experiments, which was not available during the present study. SUMMARY: Twenty-four panic disorder (PD) sufferers and 15 panic-free control subjects were tested on a range of psychometric and physiological measures, at both the start and the end of an experimental session. Subjects were tested at the beginning for state anxiety, salivary cortisol, heart rate, and blood pressure, and these tests were repeated at the end of the session. The state anxiety scores (STAI) showed a reduction in anxiety level over the test period for both groups, and there was a corresponding fall in both blood pressure and heart rate. Cortisol levels also fell over the course of the session in the control group, but in the PD group cortisol levels showed no such reduction. In addition, there was a significant difference in the levels of cortisol at the start of the session between the two groups (PD group lower). These data indicate a possible alteration in cortisol responsiveness to stress/novelty situations in PD subjects. This was considered to be consistent with previous suggestions of HPA axis dysregulation in PD patients, although our research indicates unresponsiveness rather than responsiveness to be a factor to be considered for future investigation.