L.J.P. van Doornen

Effects of Work Stress on Ambulatory Blood Pressure, Heart Rate, and Heart Rate Variability

Work stress has repeatedly been associated with an increased risk for cardiovascular disease. This study tested whether this relationship could be explained by exaggerated cardiovascular reactivity to work or impaired recovery in leisure time. Vagal tone was assessed as a possible determinant of these work stress effects. Participants included 109 male white-collar workers (age, 47.2+/-5. 3) who were monitored on 2 workdays and 1 nonworkday for ambulatory blood pressure, heart rate, and heart rate variability. Chronic work stress was defined according to Siegrists model as (1) high imbalance, a combination of high effort and low reward at work, or (2) high overcommitment, an exhaustive work-related coping style indexing the inability to unwind. All findings were adjusted for possible differences in posture and physical activity between the work stress groups. High imbalance was associated with a higher heart rate during work and directly after work, a higher systolic blood pressure during work and leisure time, and a lower 24-hour vagal tone on all 3 measurement days. Overcommitment was not associated with an unfavorable ambulatory profile. Logistic regression analysis revealed that heart rate [odds ratio 1-SD increase 1.95 (95% CI, 1.02 to 3.77)] and vagal tone [odds ratio 1-SD decrease 2.67 (95% CI, 1.24 to 5.75)] were independently associated with incident mild hypertension. Surprisingly, the values during sleep were more predictive for mild hypertension than the values during work. The results from the present study suggest that the detrimental effects of work stress are partly mediated by increased heart rate reactivity to a stressful workday, an increase in systolic blood pressure level, and lower vagal tone.

Work stress and metabolic and hemostatic risk factors

OBJECTIVE A high level of work stress has been associated with cardiovascular disease. However, the pathophysiological mechanisms underlying this association remain unclear. This study examined the effect of work stress on a cluster of metabolic and hemostatic risk factors. METHODS Blood was collected three times, on the first, third, and fifth day of a work week, from 124 middle-aged, white-collar workers. Metabolic measures were insulin, glucose, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and total cholesterol. Hemostatic measures were fibrinogen, tissue-type plasminogen activator activity, tissue-type plasminogen activator antigen, and type 1 plasminogen activator inhibitor antigen. Chronic work stress was defined according to Siegrists model as 1) a combination of high effort and low reward at work (effort-reward imbalance) or 2) high overcommitment (an exhaustive work-related coping style). RESULTS Overcommitment, but not imbalance or the imbalance-overcommitment interaction, was associated with an impaired fibrinolytic system, as reflected in decreased tissue-type plasminogen activator activity levels and increased type 1 plasminogen activator inhibitor antigen levels on all three measurement occasions. After controlling for body mass index, total cholesterol, triglycerides, high-density lipoprotein/low-density lipoprotein cholesterol ratio, glucose, and insulin, the relation between overcom-mitment and the fibrinolytic factors was attenuated but remained significant. CONCLUSIONS The results suggest that individuals with an exhaustive coping style at work have an impaired fibrinolytic capacity that is possibly due to the effects of chronic stress on insulin resistance.

Regular exercise and aerobic fitness in relation to psychological make-up and physiological stress reactivity

&NA; This study assessed the association of aerobic fitness with psychological make‐up and physiological stress‐reactivity in a group of untrained men, as well as the effects of 4 and 8 months of exercise training on these parameters. Psychological assessment included questionnaires on personality (Neuroticism, Type A, Hostility), coping styles (Anger In, Anger Out), negative affect (Depression, Anxiety), and self‐esteem. Stress reactivity was measured as the cardiovascular and urinary catecholamine response to two competitive reaction time tasks and the cold pressor test. No cross sectional relationships were found between aerobic fitness, defined as the maximal oxygen consumption during an exhaustive exercise test, and any of the psychological variables. In addition, psychological make‐up did not change as a consequence of exercise training. In further contrast to our hypothesis, aerobic fitness was associated with high, rather than low, cardiovascular reactivity. Longitudinal effects of training were limited to a reduction in the overall levels of heart rate and diastolic blood pressure. This suggests that regular exercise does not increase the resistance to stress‐related disease by influencing psychological make‐up or acute psychophysiologic reactivity.

Effects of exercise training on plasminogen activator inhibitor activity.

Plasminogen activator inhibitor (PAI) activity, an important regulator within the fibrinolytic system, has been shown to be a risk indicator for venous and arterial thrombosis. The present study aimed to test the effects of exercise training on PAI activity, and to link possible changes in PAI activity to changes in cardiovascular fitness, body composition, and the lipid profile. Four groups of previously sedentary subjects were studied thrice in an 8-month period. A long-term training group (N = 11) trained during the entire 8-month period. A detraining group (N = 14) trained for 4 months and then reverted to sedentary habits. A postponed training group (N = 16) trained only during the second 4-month period, and a no-training control group (N = 9) remained untrained throughout the entire 8-month period. PAI activity always decreased in response to training, but the training effects were small and spontaneous seasonal shifts in PAI activity of the control groups clouded their interpretation. Furthermore, detraining failed to influence PAI activity and training-induced changes in PAI activity were not related to simultaneous changes in maximal oxygen consumption, diastolic blood pressure, triglycerides, or percentage body fat, and inconsistently related to the training-induced changes in LDL-cholesterol and HDL-cholesterol. The occurrence of simultaneous changes in body fat, blood pressure, and the lipid profile underscores the potential of regular exercise to protect against cardiovascular disease. Whether these beneficial effects are accompanied by changes in the fibrinolytic system remains to be proven.

Smoking and sports participation

It has long been recognized that both smoking and sports participation tend to cluster in families. In this chapter, we first describe the current status of smoking and sports participation as cardiovascular risk factors. After an outline of the principles of the quantitative genetic approaches to the analysis of individual differences in behaviour, we will review the literature on genetic and environmental determinants of smoking and sports participation. In the second half of this chapter, results from the Dutch Twin/Family Study of Health-Related Behavior are presented.

Aerobic fitness and the physiological stress response: A critical evaluation

Aerobically fit persons need less sympathetic activation to perform the same absolute workload than less fit persons. This led to the idea that aerobic fitness might reduce the physiological activation during psychological stress as well. Several experiments showed inconsistent results with regard to this supposed effect of fitness. The comparability of the results is hampered by the differences in operationalization of aerobic fitness and by the confusion of the terms aerobic fitness, training and habitual physical exercise. The expectancy of an effect of fitness on the physiological stress response is based on the assumption that this response resembles the response to exercise. The tenability of this assumption was examined for cardiac, vascular and hormonal responses respectively. It was concluded that the two types of responses only superficially have similarity. So a simple analogy between the stress and the exercise response does not allow a reliable prediction concerning the effect of fitness on the stress response. There are however other reasons to expect an effect. Especially the effect of fitness on adrenoceptor sensitivity suggests that the most important effect of fitness might be found in the vascular part of the stress response. It is argued that the measurement of complete response patterns, instead of isolated parameters, is a prerequisite for progress in this field. Future studies should address the question what the relative contribution of psychological and physiological factors is to the effect of fitness on the physiological stress response.

The Coronary Risk Personality: Psychological and Psychophysiological Aspects

The hypothesis was tested that psychophysiological features of the Coronary Risk Personality (CRP) already are clearly discernable before myocardial infarction (MI). Psychological test assessments wer