Acute Emotional and Cardiovascular Effects of Stressful Mental Work During Aerobic Exercise

The acute effects of engaging in challenging mental work during a single session of aerobic exercise were examined on measures of subjective mood and cardiovascular function. Fifty-seven female subjects were randomly assigned to participate in either a 10-min aerobic exercise condition or a no-exercise control condition. Half of the subjects in each group performed digits backward problems during this time period, and no mental stressors were presented to the other subjects. The results indicated that the exercise and mental stress conditions had additive effects on subjective anxiety levels and on cardiovascular responses during exercise. Both exercise and mental stress increased heart rate. In addition, exercise had anti-anxiety and vasodilative effects, but both of these influences were attenuated by opposing main effects for mental stress exposure. No effects were found for exercise on measures of cardiovascular reactivity to a later digits backward stressor. The results are consistent with previous research in suggesting that exposure to mental stressors during aerobic exercise provides no acute psychological benefits but attenuates some of the mood improvements and vasodilative effects of the exercise activity.     

Neuroendocrine and Cardiovascular Stress Reactivity in Middle-Aged Normotensive Adults with Parental History of Cardiovascular Disease

Neuroendocrine and cardiovascular stress reactivity was studied in healthy middle-aged individuals whose parental history included essential hypertension and/or myocardial infarction and a control group without parental history of cardiovascular disease. All subjects completed a rest session (1 hour) and a stress session (1 hour). The stress session included behavioral (mirror image tracing, mental arithmetic, and the Stroop color word conflict test) and physical stressors (the cold pressor test and isometric exercise). Systolic and diastolic blood pressures and heart rate were recorded at baseline before and during all stressors. Specimens for determination of urinary catecholamines and cortisol were sampled after the rest and stress sessions respectively. Generally, a parental history of hypertension but not of myocardial infarction influenced neuroendocrine and cardiovascular stress reactivity. A family history of hypertension was associated with exaggerated epinephrine, norepinephrine, and cortisol excretion during stress and with enhanced heart-rate reactivity to behavioral (mental arithmetic and mirror image tracing) but not to physical stressors (isometric exercise or the cold pressor test). We conclude that individuals with a family history of hypertension tend to display exaggerated cardiovascular and neuroendocrine reactivity to stress.     

Influence of a brief aerobic training program on heart rate and subjective response to a psychologic stressor

An experiment was conducted to determine whether a brief program of aerobic exercise would reduce the heart rate and subjective responses of high- and low-fit subjects to a psychologic stressor. Thirty-four high-fit and 34 low-fit subjects were exposed to a moderate stressor (recall of digits backwards test) while their heart rates and subjective responses were monitored. Approximately half of the high- and low-fit subjects then participated in a 13-week aerobic exercise training program, whereas the other subjects did not. After the 13-week period, the subjects were again exposed to the stressor. Results indicated that a) in the pretest the low-fit subjects showed a greater heart rate response to the stressor than the high-fit subjects, b) the training program was effective for increasing subjects' levels of aerobic fitness, and c) the training program was effective for reducing the heart rate response to the stressor of low-fit subjects. These findings provide support for the relationship between fitness and the response to psychologic stressors and they suggest that aerobic training may be an effective way of helping low-fit persons deal with psychologic stressors.     

Cardiovascular reactivity and mental stress-induced myocardial ischemia in patients with coronary artery disease

This report evaluates the relationships of hemodynamic reactivity and determinants of myocardial oxygen demand to myocardial ischemia during mental stress in coronary artery disease patients. Thirty-nine patients and 12 controls were studied by radionuclide ventriculography during three mental tasks (arithmetic, Stroop task, and simulated public speaking). Patients were subdivided into three groups based on the severity of ischemic wall motion responses to the mental stressors. Results revealed that systolic blood pressure (SBP) levels during the mental tasks and SBP reactivity (increases) to stress were highest for the severely ischemic group, lowest for controls, with the mild-moderate ischemic and nonischemic patients in between. Severely ischemic patients started out with lower double product (heart rate x SBP) levels, and reached higher levels during the Stroop and speech tasks. There were no reliable group effects for diastolic blood pressure, heart rate, or left ventricular end-diastolic volumes. Among severely ischemic patients, the most potent task in eliciting ischemia (the speech) was associated with higher cardiovascular levels and elicited greater heart rate, double product, and ventricular volume responses. The present data indicate a relationship between cardiovascular levels and reactivity and the magnitude of ischemia induced by mental stress.     

Effects of aerobic exercise training on hemodynamic responses during psychosocial stress in normotensive and borderline hypertensive type A men: a preliminary report

This study assessed the effects of aerobic exercise training on cardiovascular responses to a 5-min reaction time competition task. Twenty-seven Type A men (aged 30-56) participated in this randomized study in which 14 underwent supervised aerobic training and 13 strength training, with sessions scheduled three times per week for 12 consecutive weeks. Aerobic exercise training was associated with a 13.6% increase in VO2max compared to 2.9% for the strength group. The effects of aerobic exercise training were most evident in subjects whose initial casual blood pressure readings fell in the borderline hypertensive range (N = 5). These individuals exhibited a general reduction in diastolic blood pressure (i.e., during rest, competition, and recovery) which was associated with a fall in both heart rate and total peripheral vascular resistance. Furthermore, diastolic pressure reactivity to the competition task was attenuated in borderline hypertensive subjects who underwent aerobic conditioning. These data are interpreted as preliminary findings suggesting that borderline hypertensives may be particularly responsive to the cardiovascular benefits of aerobic conditioning. For patients who have progressed to this stage of hypertensive disease, aerobic exercise may be of ameliorative value.     

The Influence of Aerobic Exercise on Physiological Stress Responsivity

The present study examined the relationship between aerobic exercise participation and physiological stress responsivity to psychosocial stressors. Male subjects (N = 107) who were either intense aerobic exercisers, moderate aerobic exercisers, or nonexereisers completed a telephone interview, a personality assessment battery, a life stress questionnaire, and a physical exercise and hobby questionnaire. Subjects then participated in a stressful laboratory procedure where they faced two stressors: an electric shock procedure, and a difficult “intelligence test.” Pulse rate, finger pulse volume, and skin resistance were assessed during the entire laboratory procedure. Although results demonstrated consistent significant cardiovascular (i.e., pulse rate and pulse volume) differences among the exercise groups during the entire laboratory procedure in that exercisers were less physiologically reactive to the stressors and the recovery periods, most of these results failed to reach significance when statistically controlling for the baseline/anticipation-of-stressors physiological measures. The implications of this study for further research are discussed.     

Exercise training in healthy type A middle-aged men: effects on behavioral and cardiovascular responses

Thirty-six healthy Type A men (means = 44.4 years) were randomly assigned to either an aerobic exercise training group or a strength and flexibility training group. Subjects completed a comprehensive psychological assessment battery before and after the exercise programs consisting of behavioral, psychometric, and psychophysiological testing. The behavioral assessment consisted of repeated Type A interviews that were videotaped for subsequent component analyses. The psychometric testing included two self-report questionnaires to assess Type A behavior. The psychophysiological test consisted of a standard behavioral challenge, a mental arithmetic task, performed while cardiovascular responses were monitored. Aerobic exercise (AE) training consisted of 12 weeks of continuous walking or jogging at an intensity of at least 70% of subjects' initial maximal oxygen consumption (VO2max) as determined by an initial treadmill test. Strength and flexibility (SF) training consisted of 12 weeks of circuit Nautilus training with no aerobic exercise. After 12 weeks of exercise, the AE group increased their VO2max by 15%, while the SF group did not change. Both groups experienced decreases in overt behavioral manifestations of the Type A behavior pattern and self-reported Type A traits. However, the AE group showed an attenuation of heart rate, systolic and diastolic blood pressure, and estimated myocardial oxygen consumption (MVO2) during the task and had lower blood pressure, heart rate, and (MVO2) during recovery. In contrast, the SF group showed a significant reduction only in DBP during the task, which was likely due to habituation. These results support the use of aerobic exercise as a method for reducing cardiovascular risk among healthy Type A men.     

Heart period variability of trained and untrained men at rest and during mental challenge

The effect of aerobic training on parasympathetic reactivity to mental stress is unclear. Thus, the parasympathetic response, as assessed by time series analysis of heart period variability (HPV_ts), of 10 trained male runners (trained group), 10 inherently low resting heart rate untrained men (low HR group), and 10 normal resting HR men (control group) at rest and to two mental stressors was examined. Participants completed a mental arithmetic and Stroop task. Resting HPV_ts at high and medium frequencies was significantly greater for the trained and the low HR groups than for the control group. Significantly greater decreases in HPV_ts at the medium frequency during arithmetic recovery were measured for the trained and low HR groups compared with the response of the control group. Significantly greater decreases in HPV_ts at both the the high and medium frequencies during the first two epochs of the Stroop occurred only for the trained and low HR groups. These results suggest that the greater HPV_ts at rest and decline in HPV_ts during and after mental challenge is influenced by both aerobic training and genetic inheritance.     

Parental History of Essential Hypertension, Active Coping, and Cardiovascular Reactivity

Differences in cardiovascular reactivity to stress between individuals with and without a family history of essential hypertension (EH) may be affected by stimulus characteristics and/or individual differences in behavioral response. Twenty-four male students with a parental history of EH and 24 without a parental history of EH participated in two laboratory sessions during which two “active’ (mental arithmetic and the Stroop word-color interference test) stressors and one “non-active’ (isometric hand-grip) stressor were presented. Family history subjects exhibited greater systolic blood pressure responses than non-family history subjects only to the two active stressors in Session 2, despite the fact that, overall, isometric hand-grip elicited the largest responses. High-performing Stroop subjects with a parental history of EH displayed greater heart rate responses to the task than high-performing subjects without a parental history of EH in both sessions. No group differences appeared among poor performers. The degree to which a stressor encourages active coping behavior appears to be one determinant of differences in cardiovascular response between individuals with and without a family history of EH.     

Sympathetic nervous system and behavioral responses to stress following exercise training.

This study tests the hypothesis that a short-term (16 weeks) exercise program modifies sympathetic nervous system (SNS) and selected behavioral responses to acute psychological stress. Twenty-four previously sedentary middle-aged men with maximal aerobic capacity (VmaxO2) values less than 40 ml.kg-1.min-1 were assigned to experimental (n = 12) and control (n = 12) groups. All subjects performed a modified Stroop test (18 min) at pre- and postexercise training during which intravenous blood samples were drawn at three time intervals for plasma catecholamine (CA) determination. Motor performance was continuously recorded for assessment of premotor (PMT) and motor (MOT) components of reactions time. A set of anagrams were administered immediately following the modified Stroop to determine the level of cognitive fatigue induced. At both pre- and postexercise intervention, the total group (n = 24) manifested significant (p less than or equal to 0.05) elevations in state anxiety, heart rate, and plasma norepinephrine. No significant changes occurred over time on PMT or MOT. There were significantly (p less than or equal to 0.01) lengthened anagram performance scores poststress compared to nonstress values. The experimental group exercise trained 3 days/week for 16 weeks, resulting in a 20% increase in VO2max. However, there were no group differences on the CA or behavioral responses to the modified Stroop at pre- or postintervention. These findings do not support the hypothesis that short-term aerobic training significantly alters SNS activity or behavioral measures of central processing in middle-aged men exposed to an acute psychological challenge.     

The effect of noise interference, type of cognitive stressor, and order of task on cardiovascular activity

In the search for reliable, easily applicable mental stressors many researchers have investigated the propensity of mental arithmetic and Stroop color discrimination tasks to elicit a physiological stress response; some researchers have added noise interference with the expectation of larger response magnitudes. The present study investigates a number of previously untested questions by directly comparing cardiovascular responses to mental arithmetic or the Stroop task with and without noise interference in a sample of 66 young adults. Half of all subjects were exposed to the additional noise interference, all subjects responded to both types of mental stressors. Blood pressure responses did not discriminate among the stressors but noise interference consistently augmented heart rate responses during mental arithmetic. Response to the second, repeated stressor was associated with highly significant response habituation effects for blood pressure. Furthermore, when mental arithmetic was presented first, both tasks elicited comparable and large responses; when the Stroop test was presented first both tasks triggered smaller responses but of comparable magnitude. Subjective evaluations of the stressors were not predictive of overall physiological response.     

Aerobic exercise intensity and time of stressor administration influence cardiovascular responses to psychological stress

This study examined cardiovascular responses as a function of time following exercise in which participants were exposed to a laboratory stressor. Ninety (42 women) young (18-35 years old) nonsmoking normotensive participants engaged in 30 min of high and low intensity (75-80% and 50-55% VO(2) max) aerobic exercise and a sedentary control condition. Participants were randomly assigned to a laboratory stressor 5, 30, or 60 min following the exercise bout. Results indicate that low and high intensity exercise significantly reduce heart rate (HR) and systolic and diastolic blood pressure reactivity and HR recovery values. An inverse relationship between intensity of exercise and subsequent cardiovascular reactivity was found. These findings suggest attenuated stress responses following acute exercise depend both on exercise intensity and the time of exposure to psychological stress following exercise.     

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.     

Does cardiovascular reactivity to mental stress have prognostic value in postinfarction patients? A pilot study.

The possible relationship between mental stress-induced cardiovascular reactivity and clinical prognosis was examined in a pilot study of 13 postinfarction patients. All patients had previously participated in the placebo condition of a secondary intervention trial. On completion of the trial, blood pressure, heart rate, and venous plasma catecholamines were evaluated at rest and in response to a modified Stroop test on two occasions. At follow-up 39 to 64 months later, five patients had suffered a new clinical event (reinfarction and/or stroke). These patients had shown significantly larger systolic and diastolic blood pressure responses to the Stroop test than had patients who remained event-free at follow-up. Catecholamine concentrations also differed between groups during mental stress, but on only one of the two test days. Groups did not differ on baseline measurements, cardiovascular response to exercise testing, fasting serum lipid and glucose concentrations, age, or duration of follow-up.     

The effect of moderate aerobic exercise on physical fitness among women 70 years and older.

This study investigated benefits of 26 weeks of moderate aerobic exercise for women 70 years or older. Sixteen healthy women with a mean age of 72.0 years were randomized into exercise (n = 10) and control groups (n = 6). The exercise group walked on a treadmill 3 times per week for 20 min, at 70% of maximum heart rate. Oxygen uptake VO2max expressed in l/min and ml.kg-1.min-1, total exercise time on the treadmill (TET), maximum heart rate (HRmax) and body mass index (BMI) were measured at baseline and 6 months. Two-way repeated measures analysis of variance (ANOVA) determined the effect of exercise intervention. Both measures of VO2max in addition to TET were significantly improved by the moderate training program, compared to the control group. VO2max in the exercise group increased by +/- 6.6% (S.E. 2.9) measured in l/min and 8.4% (S.E. 3.2) measured in ml.kg-1.min-1. TET increased by 25.4% (S.E. 4.9) in the exercise group. The ANOVA was unable to detect significance between the exercise and control groups for HRmax or BMI. All exercising subjects finished the program, apparently tolerating the intervention. The results indicate that healthy women over the age of 70 years can increase fitness measures with a moderate training program.     

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.     

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.     

Effects of aerobic conditioning on cardiovascular sympathetic response to and recovery from challenge

Exercise has widely documented cardioprotective effects, but the mechanisms behind these effects are still poorly understood. Here, we test the hypothesis that aerobic training lowers cardiovascular sympathetic responses to and speeds recovery from challenge. We conducted a randomized, controlled trial contrasting aerobic versus strength training on indices of cardiac (pre‐ejection period, PEP) and vascular (low‐frequency blood pressure variability, LF‐BPV) sympathetic responses to and recovery from psychological and orthostatic challenge in 149 young, healthy, sedentary adults. Aerobic and strength training did not alter PEP or LF‐BPV reactivity to or recovery from challenge. These findings, from a large randomized, controlled trial using an intent‐to‐treat design, show that moderate aerobic exercise training has no effect on PEP and LF‐BPV reactivity to or recovery from psychological or orthostatic challenge. In healthy young adults, the cardioprotective effects of exercise training are unlikely to be mediated by changes in sympathetic activity.     

Effects of Prior Exercise and Recovery Duration on Oxygen Uptake Kinetics During Heavy Exercise in Humans

Prior heavy exercise (above the lactate threshold, LT) reduces the amplitude of the pulmonary oxygen uptake (VO2) slow component during heavy exercise, yet the precise effect of prior heavy exercise on the phase II VO2 response remains to be established. This study was designed to test the hypotheses that (1) prior heavy exercise increases the amplitude of the phase II VO2 response independently of changes in the baseline VO2 value and (2) the effect of prior exercise depends on the amount of external work done during prior exercise, irrespective of the intensity of the prior exercise. Nine subjects performed two 6 min bouts of heavy cycling exercise separated by 6 min baseline pedalling recovery (A), two 6 min heavy exercise bouts separated by 12 min recovery (6 min rest and 6 min baseline pedalling, B), and a bout of moderate exercise (below the LT) in which the same amount of external work was performed as during the prior heavy exercise, followed by 6 min heavy exercise (C). In both tests A and B, prior heavy exercise significantly increased the absolute VO2 amplitude at the end of phase II (by approximately 150 ml x min(-1)), and reduced the amplitude of the VO2 slow component by a similar amount. Following 12 min of recovery (B), baseline VO2, but not blood [lactate], had returned to pre-exercise levels, indicating that these effects occurred independently of changes in baseline VO2. Prior moderate exercise (C) had no effect on either the VO2 or blood [lactate] responses to subsequent heavy exercise. The VO2 response to heavy exercise was therefore dependent on the intensity of prior exercise, and the effects on the amplitudes of the phase II and slow VO2 components persisted for at least 12 min following prior heavy exercise.     

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.