The job demand-control(-support) model and physical health outcomes: A review of the strain and buffer hypotheses

Abstract

This review of the Job Demand-Control (JDC) model and the expanded Job Demand-Control-Support (JDCS) model and employees' physical health, focuses on the two prevalent views on these models. According to their view on the models researchers study different hypotheses: (a) the (iso)strain hypothesis, stating that the highest level of ill health is expected when the job is characterized by high demand and low control (and low social sup port), ot (b) the buffer hypothesis, predicting that control (and social support) can buffer the potential negative effects of high demands on physical health. It is argued that these hypotheses reflect theoretical distinct models, and that the practical implications associated with these models differ.

The review of 51 studies on the JDC(S) model reveals that the “strain” hypothesis predominates in studies of all-cause mortality, cardiovascular disease (CVD) related and specific non-CVD related health outcomes. In contrast, the “buffer” hypothesis is most prevalent in research on self-reported (psycho)somatic complaints. For the strain hypothesis as well as the buffer hypothesis the results are equivocal. Working in a high (iso)strain job appears to be associated with an elevated risk for cardiovascular disease and negative pregnancy outcomes, and increased (psycho)somatic complaints. Conclusions on other physical outcomes seem premature, considering the limited number of studies. The buffer hypothesis is supported in the few studies on CVD endpoints and in some studies on (psycho)somatic complaints.

A comparison of the validity of the two hypotheses is problematic, because they are mostly applied to a different set of outcomes. Furthermore, the analyses employed in the testing of the two hypotheses are of a different nature (non-linear versus linear).

The main recommendation for future research is to examine the validity of the strain and the buffer hypothesis concurrently, and to further explore the nature of the relationships.     

Work strain and the post-discharge adjustment of patients following a heart attack

Abstract

The role of work characteristics in determining return to work after an acute coronary event was examined. One hundred and forty nine patients were enrolled. One year post-discharge, 74 had returned to work. Work characteristics (decision latitude, and opportunity for social interaction at work), together with age, depression, and medical prognosis, correctly classified work status in 78% of cases. At 12 months post-discharge, patients who had not returned to work recorded significantly poorer levels of adjustment compared to those who had returned to work. A better quality of life is associated with a lower level of depression pre-hospitalization, ownership of a larger home, being male, and having a more positive work environment. The findings suggest that the pre-illness work environment of the patient is a factor influencing return to work, which needs to be considered in rehabilitation programmes.     

Supersonic crack motion in a harmonic lattice

Antiplane shear cracks in a harmonic square lattice have been studied in a molecular dynamics simulation. They can reach velocities larger than the shear wave velocity.     

Electromechanical behavior of single-walled carbon nanotube thin films

Carbon nanotubes have been intensively studied owing to their great potential in nanoelectronics and nanomechanical devices. Recently, experimental results have shown that single-walled carbon nanotubes (SWCNTs) change their electronic properties when subjected to strain. In this study, the electromechanical characteristics of SWCNT networks were investigated for the application of printable strain sensors on flexible substrates. SWCNT films were formed on plastic substrates of poly(ethylene terephthalate) using a spray process. In this manner, we were able to control the transparency and obtain uniform electrical properties of the films. The films are isotropic on account of the random orientation of bundles of SWCNTs. Experimental results showed a nearly linear change in the resistance across a film when it was subjected to tensile strain, even in the inelastic range of the flexible substrate. The results demonstrate the potential use of SWCNT films for highly sensitive printable strain sensors on a macroscale.     

Work stress,work–home interference and perceptions of organisational culture amongst insurance employees in Zimbabwe

The objective of the study was to determine the relationship between work stress, work-home interference, and perceptions of organisational culture amongst insurance employees in the Zimbabwean context. Data were collected from a sample of 190 employees (females=46%) who completed the Occupational Stress Inventory-Revised (OSI-R), the Work-Home Interference Questionnaire (SWING), and the Organisational Culture Index (OCI). Data analysis consisted of correlational and standard multiple regression analyses. The results revealed significant positive correlations between the sub-scales Role Overload, Role Insufficiency, Role Ambiguity, Role Boundary, Responsibilities, and Physical Environment of the OSI-R, the sub-scales Positive Work-Home Interference and Negative Work-Home Interference of the SWING, and the sub-scales Bureaucratic, Innovative and Supportive Culture of the OCI. These findings contribute to new knowledge in terms of the work stress experienced by insurance employees who are always under continuous pressure from the industry. Furthermore, it could be used to gain insight to enhance the work-life balance of insurance employees and the effect of organisational culture as perceived by insurance employees.     

The absence of numbers to express the amount may affect delay discounting with humans

Human delay discounting is usually studied with experimental protocols that use symbols to express delay and amount. In order to further understand discounting, we evaluated whether the absence of numbers to represent reward amounts affects discount rate in general, and whether the magnitude effect is generalized to nonsymbolic situations in particular. In Experiment 1, human participants were exposed to a delay‐discounting task in which rewards were presented using dots to represent monetary rewards (nonsymbolic); under this condition the magnitude effect did not occur. Nevertheless, the magnitude effect was observed when equivalent reward amounts were presented using numbers (symbolic). Moreover, in estimation tasks, magnitude increments produced underestimation of large amounts. In Experiment 2, participants were exposed only to the nonsymbolic discounting task and were required to estimate reward amounts in each trial. Consistent with Experiment 1, the absence of numbers representing reward amounts produced similar discount rates of small and large rewards. These results suggest that value of nonsymbolic rewards is a nonlinear function of amount and that value attribution depends on perceived difference between the immediate and the delayed nonsymbolic rewards.     

Psychological state and psychological strain in relation to infertility

The purpose of the study was to explore the relationship between psychological state and perceived strain in relation to fertility problems. Couples presenting at an infertility clinic completed, on two occasions seven months apart, a series of standardized measures to assess psychopathology. In addition, they completed a weekly diary rating their mood state or distress/strain over a period of 22 weeks, during which investigations and treatment were taking place. Little evidence of psychopathology was found in the sample; the weekly diaries also suggested a general lack of distress/strain, even in response to medical investigations and diagnosis. The results are discussed in the light of wide individual variations in ratings obtained from the diaries. Participants with high distress/strain scores tended to have significantly higher initial scores on the psychometric measures administered. Participants with high distress/strain scores were also more likely to show a further significant increase in distress/strain scores in relation to diagnostic information. It is argued that a task for future research is to determine the characteristics of those couples who are likely to experience difficulty in coping with the strain of infertility investigations so that counselling resources and support services can be most effectively targeted. © 1998 John Wiley & Sons, Ltd.     

Le stress au travail : du paradigme des risques psychosociaux à celui de la qualité de vie au travail

An action research using three classical models of occupational stress enabled us to verify the impact on the results obtained from the choice of model and paradigm: psychosocial risks versus Quality of work life. Four hundred and thirty-six supermarket employees answered a questionnaire including these three measures of stress, the outcomes (satisfaction, fatigue) and a possible cause (role strain). Our results validate the hypotheses of significant differences in stress prevalence levels according to the model, such as links to the factor and the consequences, as well as the importance of the perception of stress to explain the negative experience.     

Influence of plastic strain localisation on the mechanical properties of metal matrix composites

The aim of the present study is to reveal the most critical underlying factor influencing the mechanical properties of metal matrix composites (MMCs). It is shown that the mechanical properties of MMCs are essentially governed by the degree of strain localisation during plastic deformation. In other words, the MMCs exhibit superior mechanical performance only if the strain localisation is obviously inhibited and the accumulated stresses can be effectively transferred out. The work provides a new perspective in guiding the design of next-generation high-performance MMCs by suppressing the strain localisation as far as possible.