Biochemical assessment and differentiation of mental and physical effort

Abstract

Evaluation of mental effort under industrial conditions encounters both methodological and practical problems mainly because of lack of appropriate indices and difficulties in differentiation between body responses to physical and mental effort.

This paper presents a review of laboratory and field research from our laboratories aimed at finding objective indices for discrimination between body responses to mental and physical effort. The laboratory data show that urinary noradrenaline/adrenaline (NA/A) ratio decreases in response to mental tasks and increases in response to physical tasks. Under industrial conditions the predominating component of effort (mental or physical) evokes body response similar to that found during laboratory experiments. Re-analysis of data published in various other papers shows the same pattern of body response.

Another possible index for assessment of effort seems to be salivary cortisol which increases in response to both mental and physical tasks. Its deviations from the circadian pattern of excretion may represent a potential criterion for assessment of the emotional component of mental effort.     

Neuroticism,locus of control,type A behaviour pattern and occupational stress

Abstract

The aim of this study was to investigate the relationship between individual differences in personality and susceptibility to stress in the workplace. Stress in lecturers employed by a computer training organization was assessed by means of self-report and measurement of salivary cortisol output during lecturing and non-lecturing weeks. Neuroticism, Type A behaviour pattern and locus of control were measured. Self-reported stress was found to be much greater during lecturing weeks, but cortisol levels were unaffected by working conditions. There was a significant positive correlation between neuroticism and locus of control and a negative correlation between locus of control and Type A behaviour pattern that approached significance. Multiple regression was employed to explore relations between personality and stress. Subjects with lower neuroticism scores yielded a bigger increase in reported stress, in the lecturing compared with the non-lecturing week, than subjects with high neuroticism scores. Type B subjects showed a progressive decrease in cortisol over the working week while Type A counterparts showed a resurgence of cortisol towards the end of the week. Finally, Type B subjects having an internal locus of control showed a faster decline in cortisol level during the lecturing week than the other subjects. Implications of these results are discussed in terms of the importance simultaneously incorporating a variety of individual differences in personality dimensions and stress indices in research designs.     

Neuroticism, locus of control, type A behaviour pattern and occupational stress

The aim of this study was to investigate the relationship between individual differences in personality and susceptibility to stress in the workplace. Stress in lecturers employed by a computer training organization was assessed by means of self-report and measurement of salivary cortisol output during lecturing and non-lecturing weeks. Neuroticism, Type A behaviour pattern and locus of control were measured. Self-reported stress was found to be much greater during lecturing weeks, but cortisol levels were unaffected by working conditions. There was a significant positive correlation between neuroticism and locus of control and a negative correlation between locus of control and Type A behaviour pattern that approached significance. Multiple regression was employed to explore relations between personality and stress. Subjects with lower neuroticism scores yielded a bigger increase in reported stress, in the lecturing compared with the non-lecturing week, than subjects with high neuroticism scores. Type B subjects showed a progressive decrease in cortisol over the working week while Type A counterparts showed a resurgence of cortisol towards the end of the week. Finally, Type B subjects having an internal locus of control showed a faster decline in cortisol level during the lecturing week than the other subjects. Implications of these results are discussed in terms of the importance simultaneously incorporating a variety of individual differences in personality dimensions and stress indices in research designs.     

Daily recovery from work: The role of activities,effort and pleasure

Abstract

Knowledge of the cycle of work and recovery is crucial for protecting employee health and well-being and preserving working capabilities. However, the daily process of effort and recovery is not well understood. This study investigated how the time spent on activities in the work and off-job domains, and the pleasure and effort experienced while engaging in these activities, affect the daily recovery process. We expected higher levels of effort at work and during off-job time to be negatively related to recovery, and higher levels of pleasure at work and during off-job time to be positively related to recovery. We also hypothesized that pleasure would act as a buffer against the negative effects of effort. Data were collected by means of a five-day diary study (three measurements daily, before and immediately after work, and at bedtime) among 120 university academic staff. Fatigue and (low) vigour were used as indicators of (lack of) recovery. Multilevel analyses showed that pleasure in the work and off-job domains had beneficial effects on recovery. An adverse association between effort expenditure and recovery was lacking. However, in the work domain, a combination of unpleasant and effortful work activities was negatively related to recovery. These findings stress the importance of engaging in pleasant activities during work and off-job time.     

Effects of continuous military operations on physical fitness capacity and physical performance

The purposes of this study were to determine the effects of a continuous field artillery scenario on physical fitness capacity and performance and to estimate the physical intensity of the scenario by continuous heart rate monitoring. Twenty-four artillerymen comprising three, 8-man guncrews participated in an 8-day, combat-simulated operation. Body composition and measures of fitness (isokinetic strength of the arms and legs, isometric handgrip strength, dynamic lifting, and upper body anaerobic power) were determined before and immediately following the scenario. Physical performance was assessed by daily ratings from senior noncommissioned officers experienced in artillery operations. The intensity of physical activity and amount of sleep were estimated from continuously recorded heart rate using electrocardiographic tape recorders worn by the soldiers. No changes occurred in body weight or upper body anaerobic power from pre- to post-scenario. However, measures of muscular strength and lifting capacity increased by 12%-18% post-scenario. Physical performance scores were significantly higher on Days 1 and 8 compared to the other days but no differences were seen from days 2 through 7. The mean ±SD for daily sleep was 5.3 ± 1.3 h. The soldiers averaged 22 min and 2.9 min per day, respectively, at heart rates equal to or greater than 50% and 75% of their maximal heart rates. The results suggest that soldiers who are allowed 5 h sleep per day and who are required to perform at relatively moderate levels of physical intensity show no decrements in physical fitness capacity or evidence of physical fatigue for up to 8 days of continuous operations.     

Effects of experimentally induced mental and physical stress on motor unit recruitment in the trapezius muscle

Mental stress may induce muscle tension and it is thought to contribute to the development of musculoskeletal disorders. Prolonged activity of a muscle's motor units (the smallest functional units) having low activation thresholds, may cause metabolic disturbances, degenerative processes and pain. The present experiment was aimed at investigating if the same motor units are activated by mental stress as by physical demands. Seventeen participants were exposed to mental stress tests (mental arithmetic, Stroop color word) and physical demands (standardized reference contraction, force ramp contraction) in the laboratory. In addition, they were exposed to the cold pressor test. Bipolar intramuscular electromyographic (EMG) activity was measured in the trapezius muscle, which covers the upper part of the back, the neck and the shoulder, and an automatic classification programme was used to separate the contributions of the individual motor units in the compex EMG signal. Overall muscle activity was measured by bipolar surface EMG and heart rate was recorded as an indicator of stress. The mental stress induced significant increases in muscle activity ( p < .05) and in heart rate ( p < .05). In 12 out of 14 participants, one or more motor units were found to be active in mentally as well as in physically induced muscle contraction. The results indicate that mentally induced stress may contribute to keeping low threshold motor units active, even in the absence of physical demands. Considering the health risks of prolonged motor unit activity, it was concluded that lack of mental rest is an important risk factor for the development of muscular pain.     

Institutional voids,international learning effort and internationalization of emerging market new ventures

Much of the existing scholarly works portray institutional voids (IVs) in emerging economies as impeding forces against the development of new ventures. However, little attention has been paid to how such voids generate positive outcomes in emerging market new ventures. Drawing on the institutional theory, we propose IVs as crucial enablers of new venture internationalization. In addition, we investigate both how and when IVs enhance the degree to which new ventures internationalize by examining international learning effort (ILE) as a mediator and two domestic market environmental factors (i.e., environmental dynamism and competitive intensity) as important contingencies. We test our moderated mediation model using primary data gathered from 211 new ventures from Ghana. We found that ILE mediates the relationship between IVs and new venture internationalization and that both environmental dynamism and competitive intensity moderate the indirect relationship between home-country IVs and new venture internationalization. We discuss the theoretical and practical implications of this study.     

不同CSR分担模式下的闭环供应链销售努力与定价决策

本文研究考虑企业社会责任(CSR)闭环供应链的定价及销售努力问题,在制造商、零售商以及二者联合承担CSR三种模式下,分析了CSR行为对闭环供应链销售努力及定价策略的影响。研究表明,无论在何种CSR分担模式下,成员企业的CSR行为不仅有利于降低产品价格,提高零售商的销售努力水平、产品销量及废旧产品回收效果,还有效的增加了制造商的社会福利、第三方及系统的总利润。当制造商或零售商单独承担CSR时,第三方及闭环供应链整体的利润均相等且大于二者联合承担CSR时。当制造商和零售商联合承担CSR时,二者的社会福利均大于其单独承担CSR时,且主导零售商的社会福利较之制造商更大。     

A conceptual framework for the study of work and mental health

Abstract

The key features which influence mental health both in jobs and unemployment are brought together within a single perspective. Three principal axes of affective well-being are identified as warranting investigation, and it is suggested that nine environmental features are of primary importance. The impact of these features on mental health is viewed as analogous to the influence of vitamins on physical health, with an explicit non-linearity in the relationship. This ‘vitamin model’ is extended to permit examination of individual differences (for example, in terms of baseline values and specific matching characteristics), and empirical evidence is summarized. It is concluded from previous research that job features do not interact synergistically in relation to employee well-being, although this possibility may not yet have been adequately tested. The framework is suggested to be adequately comprehensive, but, as is the case with other models, it requires development in respect of the specific mechanisms operating between environmental features and mental health.     

A conceptual framework for the study of work and mental health

The key features which influence mental health both in jobs and unemployment are brought together within a single perspective. Three principal axes of affective well-being are identified as warranting investigation, and it is suggested that nine environmental features are of primary importance. The impact of these features on mental health is viewed as analogous to the influence of vitamins on physical health, with an explicit non-linearity in the relationship. This 'vitamin model' is extended to permit examination of individual differences (for example, in terms of baseline values and specific matching characteristics), and empirical evidence is summarized. It is concluded from previous research that job features do not interact synergistically in relation to employee well-being, although this possibility may not yet have been adequately tested. The framework is suggested to be adequately comprehensive, but, as is the case with other models, it requires development in respect of the specific mechanisms operating between environmental features and mental health.     

Locations and vehicle routing designs of physical distribution systems

The design of a physical distribution system (PDS) involves the determination of the number and locations of distribution centres, estimation of required vehicle numbers and design of vehicle routings. Due to the enormous numbers of possible combinatorial designs of the system, it is difficult to obtain an optimal design in acceptable computation effort on many occasions. In this paper, a new solution framework for the design of PDS by implementing the genetic algorithm (GA) is presented. With the characteristic of simultaneous optimization of a large population of configuration, the proposed methodology has been proved to be an extremely efficient optimizer. In the experimental simulation conducted in this paper, it also indicates this approach can provide a near-optimal solution to the design of PDS. To analyse the growth and decay of many schemas contained in the population, the effects of the operation of reproduction, crossover and mutation on the schema are studied. The simulation evaluation about the system performance and genetic parameters is presented along with the discussions at the end of this paper.     

Gender stereotypes explain different mental prototypes of male and female leaders

Previous research has demonstrated that social stereotypes associated with women's gender can preclude them from leadership positions. It remains unclear whether these stereotypes affect how people perceive male and female leaders, however. To examine people's stereotypes, we extracted their mental representations of male and female leaders and typical men/women (referred to as nonleaders) using reverse correlation. We then asked perceivers to rate these prototypes’ apparent leadership ability and traits related to power and warmth across contexts that represented typically masculine, feminine, or neutral domains. Leaders in a feminine context appeared more leaderlike than nonleaders, but as equally leaderlike in neutral and masculine contexts. Moreover, female leader faces appeared more powerful than female nonleader faces but male leader and nonleader faces appeared equally powerful. Male leaders were perceived as warmer than male nonleaders, however, whereas female leaders and nonleaders were perceived as equally warm. Thus, people’s gender, social stereotypes, and the context in which leaders are judged influence how people conceive of male and female leaders, with counterstereotypical attributes distinguishing leaders within their gender.     

The rise and fall? Of mental stress claims in the USA

Occupation-related mental stress has been associated with significant loss in terms of diminished productivity, higher absenteeism, and increased workers' compensation claims. The Liberty Mutual Group workers' compensation data were analysed for the years 1984-93 for mental stress-related claims. This represented over 7 million claims, over 17000 of which were identified as mental stress-related. The proportion of all stress claims was estimated for each year. The proportion by gender, age and occupation (job classification code and occupation name) was also described. Stress claims increased during the late 1980s, peaking in 1991, accounting for 0.48% of all claims and 1.69% of all claims costs, and has declined since. Even at its peak, mental stress claims were not a major portion of workers' compensation losses. However, they are expensive. The average costs of a stress claim in 1993 was about $13000. The state of California accounts for 60% of the claims reported to Liberty Mutual over this 10-year period. In 1993 women accounted for 51% of the stress claims and about 30% of all claims. The mean age of workers with stress claims was 39.3 years, with most stress claims from 30 to 34 year-olds. High-risk occupations and industries include banks, insurance companies, general labourers, management, salespersons, and drivers. The current decline in stress claims can largely be explained by a combination of changes in unemployment, increasing litigation, and changes in law in California and other states that made more stringent the requirements whereby a mental stress claim can be considered work-related. While the data presented are helpful for comparing stress claims to all claims reported to Liberty Mutual and for identifying high-risk occupations and industries, because of the uniqueness of the stress claim selection algorithm and the uncertainties with cost estimates, the cost figures are not directly comparable to other claims reporting systems.     

Stress, physical activity and coronary heart disease

Recent years have witnessed an increasing popularity of corporate fitness programmes. Regular physical activity and, in particular, high aerobic fitness are associated with a lower risk of coronary heart disease. Apart from its beneficial effects on resting levels of blood pressure and cholesterol, fitness is believed to reduce the impact of psychological stress. This hypothesis has been put to the test in 33 studies examining the physiological stress response of groups selected to differ in their fitness level. Although some evidence was found for a reduced response to stress in high fit subjects, the effects were not very strong. During 54 confrontations with a stressful task, significantly lower heart rate reactions in high fit subjects were seen in only nine tasks (17%). With nine out of 36 stressors (28%), fit subjects showed a lower diastolic blood pressure response. However, in combination with a frequently found reduction in basal levels, the high fit showed a consistently favourable cardiovascular profile under stress. This adaptation may reflect the benefits of regular exercise over a more sedentary lifestyle, but a combined influence of genetic make-up on cardiovascular reactivity and fitness cannot be ruled out.     

Job stress, satisfaction and mental health of factory workers in Bangladesh

The present study examined the relationship between job stress, job satisfaction and mental health, and attempted to assess the effects of job stress on different parameters of satisfaction and mental health in the context of two groups of Bangladeshi factory workers. There were 26 subjects in a 'high stress' group and 33 in a 'low stress' group. Individual data were collected by using the Stress and Arousal Checklist, the Job Satisfaction Scale, the General Health Questionnaire, absenteeism by sick leave, a self-esteem at work scale and heart rate monitor. Chi-square and t-tests were applied in the analyses of these data by group. The results, quite expectedly, showed that a greater number of high stress subjects were dissatisfied and had poorer mental health than low stress subjects. The results also showed that low stress subjects were significantly more satisfied and possessed better mental health than the high stress subjects. It would appear that the experience of stress plays an important role in determining the quality of working life of Bangladeshi factory workers having similar consequences in terms of health and well-being to those observed in developed countries. The dynamics of absenteeism in Bangladesh are discussed.     

The associations between work stress and mental health: A comparison of organizationally employed and self-employed workers

This study examined the associations between work stressors and mental health in organizationally employed and self-employed workers, and with the numbers of general practitioner (GP) services used by these two employment groups. The participants were selected from those already taking part in the PATH Through Life Project, in Australia. A total of 2275 men and women aged from 40 to 44 years participated in a community survey and were in the labour force at the time of the interview. Those who participated entered responses into a hand-held computer under the supervision of an interviewer. A total of 14.2% of the group identified themselves as self-employed. Respondents also provided details of their occupation and the extent to which they experienced work stressors. Some 72.6% of these participants gave consent for information on their use of GP services over a 12-month period to be obtained from national insurance records. We found that self-employed men and women reported more decision authority than the organizationally employed, while self-employed women also had more manageable job demands. Self-employment offered men no health benefit. However, women who were self-employed reported worse physical health than their organizationally employed counterparts. While work stress factors were most likely to be associated with the use of GP services by self-employed men, the use of those services by women was more strongly associated with their experiences of stress in organizational employment. Overall, self-employment was found to be associated with relatively few mental health benefits.     

Psychosocial work environment and mental health among travelling salespeople

Travelling salespeople have a rather unusual working environment, with long periods of absence from their firm and a low level of social contacts with colleagues. Furthermore, they are exposed to high demands in their work, which may conflict with a normal family life. In this paper a cross-sectional study of psychosocial work environment and mental health of Danish travelling salespeople is described. A sample of 1,306 travelling salespeople filled in a questionnaire (response rate 68%). The results indicate that poor mental health is associated with a number of demand indicators: number of working hours per week, number of customers per week, non-day work, and a high level of perceived job demands. On the other hand, the number of hours spent with customers per week is positively associated with mental health. The authors did not find the expected associations between poor mental health and several factors such as number of hours away from firm, nights away from home, and a low degree of perceived support from colleagues and superiors. It is concluded that the main stressors of travelling salespeople are long working hours, many customers, non-day work and high perceived psychological demands in general.     

Psychosocial work environment and mental health among travelling salespeople

Travelling salespeople have a rather unusual working environment, with long periods of absence from their firm and a low level of social contacts with colleagues. Furthermore, they are exposed to high demands in their work, which may conflict with a normal family life. In this paper a cross-sectional study of psychosocial work environment and mental health of Danish travelling salespeople is described. A sample of 1,306 travelling salespeople filled in a questionnaire (response rate 68%). The results indicate that poor mental health is associated with a number of demand indicators: number of working hours per week, number of customers per week, non-day work, and a high level of perceived job demands. On the other hand, the number of hours spent with customers per week is positively associated with mental health. The authors did not find the expected associations between poor mental health and several factors such as number of hours away from firm, nights away from home, and a low degree of perceived support from colleagues and superiors. It is concluded that the main stressors of travelling salespeople are long working hours, many customers, non-day work and high perceived psychological demands in general.     

Job design and levels of physical and mental strain among Australian prison officers

Over the past 15 years much has been made of the moderating influence of job discretion and support in occupations that are perceived to be high in demands. Such an effect seems to be most prevalent when subject populations are large and heterogeneous. One aim of this study was to examine the influence of subjective perceptions of these variables on strain reactions among a group of relatively homogeneous workers such as, in the present study, prison officers (n = 274). A second aim was to extend previous research and examine the joint influence of negative affectivity and perceptions of demands, discretion, and support on mental and physical well-being. It was hypothesized that those high in negative affect would be particularly strained by jobs perceived as being demanding. The hypothesized relationship between job demands, discretion and support were found to be weak and at times inconsistent. Social support, in particular, was found to have both positive and negative consequences for different aspects of well-being. Those high in negative affect were in general found to suffer lower mental well-being. More importantly, the interactive effect of negative affectivity and job demands was found to significantly predict the majority of the dependent variables used in this study. The valences of these relationships were inconsistent and are interpreted in light of Warr's (1987) vitamin model of stress.

There are several conclusions that can be drawn from the present study. Negative affectivity appears to have a truly interactive effect with job components, job demands in particular, to influence a range of variables relating to physical and mental health as well a job-related attitudes. The nature of these effects, however, suggests a dissociation in the ways that different independent variables influence a range of indices of well-being and affect. This result requires further investigation since there are important theoretical implications which will follow if the data are replicable.

In order to examine such complex effects, in addition to the need for more longitudinal studies, it is also important that standardized measures of job components are developed so that levels of stress exposure can be equated and their impact assessed across organizational settings.

Finally, the data reported in this study suggest that some effective stress management may be undertaken by adopting selection strategies which take into consideration individual characteristics. In view of the fact that individual stress management programmes are of unproven benefit (Murphy 1986, 1988) such an approach is recommended especially for those organizations which are highly constrained in the services that must be performed.     

Work and mental disorders in a German national representative sample

Abstract

Most previous studies concerning the associations between work and mental ill-health have used dimensional self-report questionnaires for mental health problems (e.g., depressive symptoms). This study contributes to occupational health research by providing standardized clinical diagnoses based on DSM-IV criteria. A total of 2329 employees (age 18–65 years) took part in a structured, computer-assisted clinical interview (DIA-X/M-CIDI). Further, they specified whether their job was characterized by physical workload, overtime, or stress, and evaluated whether they feel impaired by each job characteristic. Results show that substance abuse/dependence (including nicotine dependence) was the highest prevalent mental disorder in German employees (12 month prevalence: 14.4%; only alcohol and illicit substance abuse/dependence: 4.9%) followed by anxiety (12.0%) somatoform (9.7%), and affective (9.3%) disorders. Sequential logistic regression analyses showed significant associations between the presence of stress at work and affective and somatoform disorders. Furthermore, feeling impaired by stress at work was strongly associated with anxiety, affective, somatoform disorders, and substance abuse/dependence. Beside work, personal characteristics, primarily gender, were associated with mental disorders in employees. However, except for affective disorders, gender did not modify the association between job characteristics and mental disorders. Taken together, results corroborate the necessity of considering mental disorders at work. Further studies to define the relation between work and mental disorders in employees are strongly recommended and should include objective analyses of job characteristics.