The impact of job strain on the predictive validity of the theory of planned behaviour: an investigation of exercise and healthy eating

Development, internal reliability and preliminary construct validity of the Dutch Dietary Intention Evaluation Tool for In-patients (DIETI)

BACKGROUND AND AIMS

Diet is important in prevention and management of non-communicable disease and in particular, cardiovascular disease. Recently, more hospitals gear towards healthier dietary policies, however, a tool to assess the effect of these interventions in patient populations is currently lacking. The Theory of Planned Behavior (TPB) is generally used to assess health-related behavior and offers a framework for development of questionnaires. In this study, we aim to evaluate the reliability, internal consistency and preliminary construct validity of the newly developed Dietary Intention Evaluation Tool for In-hospital patients (DIETI) which is based on the TPB.

METHODS AND RESULTS

An expert panel constructed the item list of the DIETI. A total of 312 patients admitted to the cardiology ward filled out the DIETI. Explanatory- and confirmatory factor analysis showed that our tool adequately discerns five TPB-consistent factors regarding a healthy diet in hospitalized patients. (N = 312, for the CFA model χ² = 313.072 (df = 160, p < 0.001, CFI = 0.939, RMSEA = 0.058). Subsequent analysis of reliability showed satisfactory to strong internal consistency of the questionnaire as a whole and all subscales (Cronbach's alpha for the subscales ranging between 0.65 and 0.88).

CONCLUSIONS

We conclude that the DIETI is an internally reliable tool to assess behavioral intentions regarding a healthy diet of in-hospital patients. Thus, this questionnaire can be used to evaluate the effect of dietary interventions aimed at hospitalized patients.

Theory of planned behaviour, psychological stressors and intention to avoid violating traffic rules: A Multi-Level modelling analysis

This study applies a multilevel model approach to test the predictive effect of the theory of planned behaviour (TPB) plus moral norm, past behaviour and crash history to account for intentions to avoid traffic violations within the context of commuting to or from work. This study also extended the theory by adding psychological stressors of perceived stress and work-family conflict. In this study, we systematically tested the direct and mediated models. A sample of Malaysian drivers (N = 482; 44.6% were men and 55.4% women), with the average age of 36.7 years (SD = 10.0) was surveyed. The self-report questionnaire contained multiple observations nested within individual drivers, with respect to 3 different driving violations. As predicted, multi-level modelling showed that within-person predictor variables of all the TPB components emerged as independent predictors, with injunctive norm being the most predictive variable, followed by self-efficacy and cognitive attitude. Intention was also predicted by moral norms and crash history. Between-person variables, gender, commuting hours and work-family conflict also had direct influences on intention (i.e., men and those with longer commuting hours and higher work-family conflict reported lower intentions). Substantial support for the mediation model was found, confirming that stressors indirectly influence intentions through effects on the social cognitive components. The implications of the linkage between the social cognition and stressors for developing potential broader interventions focusing on multiple violation behaviours and designing appropriate safety policies to reduce commuting crashes are discussed.

The Dyadic Health Influence Model

Relationship partners affect one another's health outcomes through their health behaviors, yet how this occurs is not well understood. To fill this gap, we present the Dyadic Health Influence Model (DHIM). The DHIM identifies three routes through which a person (the agent) can impact the health beliefs and behavior of their partner (the target). An agent may (a) model health behaviors and shape the shared environment, (b) enact behaviors that promote their relationship, and/or (c) employ strategies to intentionally influence the target's health behavior. A central premise of the DHIM is that agents act based on their beliefs about their partner's health and their relationship. In turn, their actions have consequences not only for targets' health behavior but also for their relationship. We review theoretical and empirical research that provides initial support for the routes and offer testable predictions at the intersection of health behavior change research and relationship science.

Determinants of Fast-Food Consumption in Romania: An Application of the Theory of Planned Behavior

This study explores drivers of fast-food consumption in Romania using the Theory of Planned Behavior. We analyze 532 responses to an online survey and use partial least squares path modeling to estimate the relationships between the intention to consume fast food and its possible determinants. Our results show that the most significant predictor is the subjective norms (injunctive norms: β = 0.218, p < 0.001; descriptive norms: β = 0.192, p < 0.001). Among the affective and cognitive attitudes, only the latter is statistically significant in predicting the intention (β = 0.088, p = 0.020), while perceived behavioral control is not significantly associated with intention toward fast-food consumption. We explain how our results can help policymakers to design better interventions on public health concerns about fast-food consumption and population obesity, especially children obesity.

The mediating role of unhealthy behaviors and body mass index in the relationship between high job strain and self-rated poor health among lower educated workers

Objectives

The objective of this study is to examine the mediating role of unhealthy behaviors and body mass index (BMI) in the relationship between high job strain and self-rated poor health in workers with a low education.

Methods

A total of 8369 low educated workers, who participated in the Lifelines cohort study during the period 2012–2017, were included. Self-reported job strain, health behaviors (smoking, physical activity, and fruit and vegetable consumption), and BMI were assessed at baseline, and self-rated health after 2 years. To assess mediation by the health behaviors and BMI, structural equation modeling with logistic and multinomial regression analyses were performed.

Results

Workers with high job strain had a higher odds of poor health (OR 1.34; 95% CI 1.13–1.60) compared to those with low job strain. Workers with high job strain were more likely to have a lack of physical activity (OR 1.14; 95% CI 1.01–1.28), but were not more likely to smoke, to be overweight or obese, or to have a low fruit or vegetable consumption. Workers who smoke, have a lack of physical activity or are overweight or obese are more likely to report poor health (OR 1.37; 95% CI 1.16–1.60, OR 1.25; 95% CI 1.08–1.43, OR 1.37; 95% CI 1.16–1.61, OR 2.25; 95% CI 1.86–2.72). Indirect (mediating) effects of unhealthy behaviors and BMI in the relationship between high job strain and poor health were small and not statistically significant.

Conclusions

No mediating effects of unhealthy behaviors or BMI were found in the relationship between high job strain and self-rated poor health among workers with a low educational level.

Work and sport: relationships between specific job stressors and sports participation

This study examines the relationships between different job stressors and sports participation. Based on a large-scale representative sample (N = 1935), the paper tested if the number of different job stressors encountered in a job is related to sports participation. Moreover, we examined the relative impact of different stressors on sport participation. As predicted, the number of stressors encountered at work is negatively associated with leisure-time sports participation. When testing the relative effects of different job stressors, intense physical labour, shift and night work, and job insecurity (i.e. having a fixed-term contract or fearing unemployment) are negatively related to sports participation, whereas hazardous exposure (i.e. noise), bad working atmosphere, and long working hours are not related to sports participation. Hence, the total number of job stressors, but also the specificity of job stressors, should be taken into account by professionals in the fields of health research and physical activity promotion. Practioner summary: In a large-scale representative sample, we examined if different adverse job conditions are negatively related to sports participation. We found that the number of different job stressors was negatively related to sports participation. In particular, intense physical labour, shift and night work as well as job insecurity had an impact.

Factors Influencing Nutritional Behavior Among Patients With Metabolic Syndrome

Introduction. Lifestyle modification and adherence to healthy diet is crucial in the prevention and management of metabolic syndrome (MetS). Aim: The aim of the current study was to identify factors affecting healthy nutritional behaviors among patients with MetS. Methods: In this cross-sectional study, a total of 322 adults with a mean age of 40.55 ± 5.97 years were included. The diagnosis of MetS was based on the criteria suggested by the International Diabetes Federation. Nutritional attitudes, subjective norms, intention, and nutritional behaviors were assessed through a questionnaire designed by researchers. Results: The finding indicated that nutritional attitude and gender of participants were predicting factors of behavioral intention. Furthermore, nutritional attitude, behavioral intention, gender, and level of education could predict nutritional behavior in patients. However, subjective norm was a weak predictor of behavioral intention and nutritional behavior. Conclusions: The findings suggest that attitude and intention, but not subjective norms, along with some sociodemographic variables were able to predict the nutritional behavior of MetS patients that could be a basis for designing educational interventions for health promotion among them.

"That is an Awful Lot of Fruit and Veg to Be Eating". Focus Group Study on Motivations for the Consumption of 5 a Day in British Young Men

Young men do not consume enough fruit and vegetables, increasing their risk for future ill health. To understand what motivates their food choice, a novel conceptual framework that included key concepts from the theory of planned behavior and risk theory was developed. Thirty-four British men (18-24 years) took part in focus groups, where innovative visual qualitative methods provided insight into participants' motivations for fruit and vegetable consumption. Based on information from food diaries, participants were described as high (4+ portions) or low (up to 3 portions) consumers. Interviews were coded thematically into concepts and characteristics of the conceptual framework. Young men were generally unaware of the UK government's recommendation to consume 5 portions of fruit and vegetable a day and chronic health risks associated with low consumption. High consumers were motivated by perceived risk, perceived behavioral control, and health-conscious self-identity. They held internalized, holistic beliefs about diet and health, whereas low consumers' beliefs were externalized, based on physical appearances. Low consumers were driven by social influences to consume cheap, easily available convenience foods. The conceptual framework differentiated levels of fruit and vegetable consumption between the two groups and provided new information about young men's motivations for fruit and vegetable consumption.

Association Between Work-Related Factors and Diet: A Review of the Literature

The quality of workers' dietary intake could be influenced by their working conditions. This review aimed to summarize the published literature examining the association between work-related factors, such as work hours, shift work, physical strain, mental strain, job strain, support, and diet quality. The literature search, conducted in PubMed, was limited to articles published from 2000 to 2017, written in English, available online, and among workers employed in high-income countries. The search resulted in 16 articles that met the criteria. Although there was some evidence of unhealthy diet among shift workers, data on the diet quality in association with other work-related factors, such as number of hours worked, physical, mental, and job strain, and worksite support were scarce. Further studies are need for purposes better defining the association between work-related factors and quality of workers' diet.

Work Factors, Work-Family Conflict, the Theory of Planned Behaviour and Healthy Intentions: A Cross-Cultural Study

The present study examined the roles of work factors (i.e. job demands and job resources), work-family conflicts and culture on predictors of healthy intentions (fruit and vegetable consumption, low-fat diet and physical activity) within the framework of the theory of planned behaviour (TPB). Employees from the United Kingdom (N = 278) and Malaysia (N = 325) participated in the study. Results indicated that higher job demands were significantly related to lower intentions to eat a low-fat diet. Women reported higher intentions to eat a low-fat diet than men did, while participants from the United Kingdom had lower intentions to engage in physical activity compared with those from Malaysia. The efficacy of TPB variables in explaining intentions was verified, with perceived behavioural control (i.e. self-efficacy), attitudes and descriptive norms combined with past behaviour predictive across the samples. The results also suggest the roles of culture and work interference with family variables in moderating TPB-intention relationships and confirm that TPB variables mediate the effects of job demands and job resources on intentions. Practically, to promote health, identifying strategies to reduce stress factors; specifying important cognitive factors affecting work factors and thus, healthy intentions; and acknowledging cultural-specific determinants of healthy intentions are recommended. Copyright © 2015 John Wiley & Sons, Ltd.

The effects of stress on physical activity and exercise

BACKGROUND

Psychological stress and physical activity (PA) are believed to be reciprocally related; however, most research examining the relationship between these constructs is devoted to the study of exercise and/or PA as an instrument to mitigate distress.

OBJECTIVE

The aim of this paper was to review the literature investigating the influence of stress on indicators of PA and exercise.

METHODS

A systematic search of Web of Science, PubMed, and SPORTDiscus was employed to find all relevant studies focusing on human participants. Search terms included "stress", "exercise", and "physical activity". A rating scale (0-9) modified for this study was utilized to assess the quality of all studies with multiple time points.

RESULTS

The literature search found 168 studies that examined the influence of stress on PA. Studies varied widely in their theoretical orientation and included perceived stress, distress, life events, job strain, role strain, and work-family conflict but not lifetime cumulative adversity. To more clearly address the question, prospective studies (n = 55) were considered for further review, the majority of which indicated that psychological stress predicts less PA (behavioral inhibition) and/or exercise or more sedentary behavior (76.4 %). Both objective (i.e., life events) and subjective (i.e., distress) measures of stress related to reduced PA. Prospective studies investigating the effects of objective markers of stress nearly all agreed (six of seven studies) that stress has a negative effect on PA. This was true for research examining (a) PA at periods of objectively varying levels of stress (i.e., final examinations vs. a control time point) and (b) chronically stressed populations (e.g., caregivers, parents of children with a cancer diagnosis) that were less likely to be active than controls over time. Studies examining older adults (>50 years), cohorts with both men and women, and larger sample sizes (n > 100) were more likely to show an inverse association. 85.7 % of higher-quality prospective research (≥ 7 on a 9-point scale) showed the same trend. Interestingly, some prospective studies (18.2 %) report evidence that PA was positively impacted by stress (behavioral activation). This should not be surprising as some individuals utilize exercise to cope with stress. Several other factors may moderate stress and PA relationships, such as stages of change for exercise. Habitually active individuals exercise more in the face of stress, and those in beginning stages exercise less. Consequently, stress may have a differential impact on exercise adoption, maintenance, and relapse. Preliminary evidence suggests that combining stress management programming with exercise interventions may allay stress-related reductions in PA, though rigorous testing of these techniques has yet to be produced.

CONCLUSIONS

Overall, the majority of the literature finds that the experience of stress impairs efforts to be physically active. Future work should center on the development of a theory explaining the mechanisms underlying the multifarious influences of stress on PA behaviors.

An Integrative Review

The purpose of this review is to synthesize the research evidence for the role of the work environment—workplace physical activity policies and resources and job strain factors—in explaining physical activity in white-collar workers. White-collar workers are at risk for developing a sedentary lifestyle, which contributes to all-cause mortality. Understanding how work environment can influence worker physical activity is important for the development of effective interventions. We reviewed 15 research articles that describe the relationship between work environment factors and physical activity in predominantly white-collar workers. Relatively consistent evidence was found for the effects of supportive workplace policies and resources. Weak evidence was found for the effects of job strain. Both work environment factors have the potential to influence physical activity but require further exploration to fully understand their contribution to physical activity in white-collar workers. Limitations and implications are discussed.

Job strain as a risk factor for leisure-time physical inactivity: an individual-participant meta-analysis of up to 170,000 men and women: the IPD-Work Consortium

Unfavorable work characteristics, such as low job control and too high or too low job demands, have been suggested to increase the likelihood of physical inactivity during leisure time, but this has not been verified in large-scale studies. The authors combined individual-level data from 14 European cohort studies (baseline years from 1985–1988 to 2006–2008) to examine the association between unfavorable work characteristics and leisure-time physical inactivity in a total of 170,162 employees (50% women; mean age, 43.5 years). Of these employees, 56,735 were reexamined after 2–9 years. In cross-sectional analyses, the odds for physical inactivity were 26% higher (odds ratio = 1.26, 95% confidence interval: 1.15, 1.38) for employees with high-strain jobs (low control/high demands) and 21% higher (odds ratio = 1.21, 95% confidence interval: 1.11, 1.31) for those with passive jobs (low control/low demands) compared with employees in low-strain jobs (high control/low demands). In prospective analyses restricted to physically active participants, the odds of becoming physically inactive during follow-up were 21% and 20% higher for those with high-strain (odds ratio = 1.21, 95% confidence interval: 1.11, 1.32) and passive (odds ratio = 1.20, 95% confidence interval: 1.11, 1.30) jobs at baseline. These data suggest that unfavorable work characteristics may have a spillover effect on leisure-time physical activity.

Employees’ perceptions of the impact of work on health behaviours

Research examining the impact of work on health behaviours has rarely provided a complete picture of the impact across health behaviours. Twenty-four employees were interviewed about their smoking, drinking, exercise and eating. Themes included the impact of the work environment, including policy, convenience and workplace cultural norms; business events effecting one’s routine and again convenience and workplace cultural norms; being busy at work effecting time and energy for healthy behaviour; and work stress leading to health behaviours being used as coping responses on bad and good days. The impact of work is similar across health behaviours and is primarily detrimental.

Work environment and psychosocial factors affecting physical activity among Taiwanese information technology professionals: a structural equation modeling approach

OBJECTIVE

To examine the relationships among work environment, psychosocial factors, and physical activity (PA) among information technology (IT) professionals.

METHODS

This was a cross-sectional survey of 576 IT professionals from three IT companies in Taiwan. Structural equation modeling was used to test a theoretically supported model using social cognitive theory, incorporating variables from the demand-control model.

RESULTS

Higher levels of PA were positively associated with supportive workplace environments, positive outcome expectations, and self-efficacy for PA. Self-efficacy partially mediated the effects of supportive workplace environments on PA. Job strain had an indirect effect on PA through self-efficacy. The final model accounted for 31% of the variance in PA.

CONCLUSIONS

Work environment and psychosocial factors are both important. Workplace PA interventions directed toward individuals' self-efficacy and outcome expectations in the context of supportive environments may be useful.

The role of context stability and behavioural stability in the mere measurement effect: An examination across six behaviours

Asking about intentions and behaviour may alter future reports of health behaviours due to the stability of the behaviours (behavioural stability hypothesis), or changes in performance context (context stability hypothesis). Two studies ( Ns = 116, 177) confirmed the distinction between stable and unstable behaviours and explored context stability for six health-related behaviours. Study 3 used a longitudinal intervention design in which the intervention group ( N time 1 = 292, N time 2 = 149) reported their intentions and past-behaviours at time 1 while the non-intervention group ( N = 118) did not. The context stability hypothesis was supported.

Determinants of fast-food consumption. An application of the Theory of Planned Behaviour

This study applied and extended the Theory of Planned Behaviour (TPB; Ajzen, 1988) in an examination of the variables influencing fast-food consumption in an Australian sample. Four hundred and four participants responded to items measuring TPB constructs and retrospective and prospective measures of fast-food consumption. Additional independent variables included: Consideration of Future Consequences (Strathman, Gleicher, Boninger, & Edwards, 1994), Fear of Negative Evaluation (Leary, 1983), and Self-Identification as a Healthy Eater Scale (Armitage & Conner, 1999a). Structural Equation Modeling (SEM) was used to examine predictors of consumption. SEM indicated that the TPB successfully predicted fast-food consumption. Factor analyses assisted in the definition of constructs that underlay attitudes towards fast foods. These constructs were included in an 'extended' TPB model which then provided a richer source of information regarding the nature of the variables influencing fast-food consumption. Findings suggest that fast-food consumption is influenced by specific referent groups as well as a general demand for meals that are tasty, satisfying, and convenient. These factors reflect immediate needs and appear to override concerns about longer-term health risks associated with fast food. Results are discussed in the context of possible applications.

The benefits of sustained leisure-time physical activity on job strain

BACKGROUND

The long-term effects of leisure-time physical activity (LTPA) on job strain have not been assessed in a large prospective population-based cohort study.

AIMS

To examine the relationship between the LTPA and the prevalence of job strain.

METHODS

The participants were 861 full-time employees (406 men and 455 women), aged 24-39 years in 2001, from the ongoing Cardiovascular Risk in Young Finns Study. LTPA was assessed using a self-report questionnaire in 1992 and in 2001. The participants were grouped into four categories according to tertiles of LTPA index at two time points: persistently active, increasingly active, decreasingly active and persistently inactive. Job strain was measured in 2001 by indicators of job demands and job control.

RESULTS

Baseline LTPA was inversely associated with job strain (P < 0.001) and job demands (P < 0.05) and directly associated with job control (P < 0.05) in both sexes in a model adjusted for the change in 9-year LTPA, age, educational level, occupational status and smoking. Compared with persistently active participants, persistently inactive participants had a 4.0-fold higher job strain after adjustment for the confounders. Similarly, persistently inactive participants had a 2.7-fold higher job demands and a 1.8-fold lower job control. Decreasing physical activity was independently associated with high job strain (P < 0.01) and with low job control (P < 0.01).

CONCLUSIONS

Participation in regular LTPA during leisure may help young adults to cope with job strain. A long-term benefit of LTPA may play a role in the development of mental well-being.

Psychosocial determinants of fruit and vegetable intake in adult population: a systematic review

BACKGROUND

Accumulating evidence suggests that fruit and vegetable intake (FVI) plays a protective role against major diseases. Despite this protective role and the obesity pandemic context, populations in Western countries usually eat far less than five servings of fruits and vegetables per day. In order to increase the efficiency of interventions, they should be tailored to the most important determinants or mediators of FVI. The objective was to systematically review social cognitive theory-based studies of FVI and to identify its main psychosocial determinants.

METHODS

Published papers were systematically sought using Current Contents (2007-2009) and Medline, Embase, PsycINFO, Proquest and Thesis, as well as Cinhal (1980-2009). Additional studies were identified by a manual search in the bibliographies. Search terms included fruit, vegetable, behaviour, intention, as well as names of specific theories. Only studies predicting FVI or intention to eat fruits and vegetables in the general population and using a social cognitive theory were included. Independent extraction of information was carried out by two persons using predefined data fields, including study quality criteria.

RESULTS

A total of 23 studies were identified and included, 15 studying only the determinants of FVI, seven studying the determinants of FVI and intention and one studying only the determinants of intention. All pooled analyses were based on random-effects models. The random-effect R2 observed for the prediction of FVI was 0.23 and it was 0.34 for the prediction of intention. Multicomponent theoretical frameworks and the theory of planned behaviour (TPB) were most often used. A number of methodological moderators influenced the efficacy of prediction of FVI. The most consistent variables predicting behaviour were habit, motivation and goals, beliefs about capabilities, knowledge and taste; those explaining intention were beliefs about capabilities, beliefs about consequences and perceived social influences.

CONCLUSIONS

Our results suggest that the TPB and social cognitive theory (SCT) are the preferable social cognitive theories to predict behaviour and TPB to explain intention. Efficacy of prediction was nonetheless negatively affected by methodological factors such as the study design and the quality of psychosocial and behavioural measures.

Association of workplace chronic and acute stressors with employee weight status: data from worksites in turmoil

OBJECTIVES

To examine the independent and joint effects of psychosocial chronic and acute stressors with weight status and to report the intraclass correlation coefficient for body mass index (BMI).

METHODS

Baseline data on 2782 employees from a group-randomized weight gain prevention intervention were examined to investigate the effect of high job strain and job insecurity on BMI and on the odds of overweight/obesity including potential confounders and mediating variables. Data were analyzed using mixed models.

RESULTS

The mediating variables removed the effect of high job strain on weight (beta = 0.68, P = 0.07; odds ratios = 1.34, confidence interval = 1.00 to 1.80) whereas job insecurity was never significant. Intraclass correlation coefficient for BMI is 0.0195, 0.0193, and 0.0346 overall, for men and women, respectively.

CONCLUSION

Worksite wellness should target health enhancing behaviors to minimize the health effects of psychosocial work conditions.

Predicting breakfast consumption: an application of the theory of planned behaviour and the investigation of past behaviour and executive function

OBJECTIVES

The objective of the current study is to examine the determinants of breakfast consumption with the application of the Theory of Planned Behaviour (TPB; 1991) and investigate the additional variables of past behaviour and executive function.

DESIGN

A prospective 1-week study investigating the predictive ability of TPB variables, past behaviour and executive function was utilized.

METHODS

Ninety-six participants were administered two measures of executive function (response inhibition and planning) and completed self-report questionnaires regarding their attitudes, subjective norms, perceived control, intentions and past behaviour of breakfast consumption. One week later, participants returned a follow-up questionnaire on their behaviour.

RESULTS

The result of the study showed that the TPB significantly predicted intentions and prospective behaviour of breakfast consumption, however, past behaviour was found to be the strongest predictor of future behaviour. Considering executive function, response inhibition was not found to predict behaviour, however, planning ability explained unique variance in behaviour and moderated the association between intention and behaviour.

CONCLUSIONS

The findings support the use of the TPB in explaining breakfast eating habits, and suggest that executive function of planning may be somewhat useful to predict this behaviour. The significance of past behaviour also suggests that breakfast consumption may commonly be a stable, habitual behaviour that may undermine the need for self-regulation. Implications for creating behavioural-change interventions are discussed.

Moderators of the intention-behaviour and perceived behavioural control-behaviour relationships for leisure-time physical activity

BACKGROUND

Intention is a key determinant of action. However, there is a gap between intention and behavioural performance that remains to be explained. Therefore, the aim of this study was to identify moderators of the intention-behaviour and perceived behavioural control (PBC)- behaviour relationships for leisure-time physical activity.

METHOD

This was tested in reference to Ajzen's Theory of Planned Behaviour. A sample of 300 volunteers, 192 women and 108 men, aged 18 to 55, participated in the study. At baseline, the participants completed a self-administrated psychosocial questionnaire assessing Ajzen's theory variables (i.e., intention and perceived behavioural control). The behavioural measure was obtained by mail three months later.

RESULTS

Multiple hierarchical regression analyses indicated that age and annual income moderated the intention-behaviour and PBC-behaviour relationships. However, in the final model predicting behaviour (R2 = .46), only the interaction term of PBC by annual income (beta = .24, p = 0.0003) significantly contributed to the prediction of behaviour along with intention (beta = .49, p = 0.0009) and past behaviour (beta = .44, p < 0.0001).

CONCLUSION

Physical activity promotion programs would benefit not only from focusing on increasing the intention of low intenders, but also from targeting factors that moderate the perceived behavioural control-behaviour relationships.

Genetic influences on exercise participation in 37,051 twin pairs from seven countries

BACKGROUND

A sedentary lifestyle remains a major threat to health in contemporary societies. To get more insight in the relative contribution of genetic and environmental influences on individual differences in exercise participation, twin samples from seven countries participating in the GenomEUtwin project were used.

METHODOLOGY

Self-reported data on leisure time exercise behavior from Australia, Denmark, Finland, Norway, The Netherlands, Sweden and United Kingdom were used to create a comparable index of exercise participation in each country (60 minutes weekly at a minimum intensity of four metabolic equivalents).

PRINCIPAL FINDINGS

Modest geographical variation in exercise participation was revealed in 85,198 subjects, aged 19-40 years. Modeling of monozygotic and dizygotic twin resemblance showed that genetic effects play an important role in explaining individual differences in exercise participation in each country. Shared environmental effects played no role except for Norwegian males. Heritability of exercise participation in males and females was similar and ranged from 48% to 71% (excluding Norwegian males).

CONCLUSIONS

Genetic variation is important in individual exercise behavior and may involve genes influencing the acute mood effects of exercise, high exercise ability, high weight loss ability, and personality. This collaborative study suggests that attempts to find genes influencing exercise participation can pool exercise data across multiple countries and different instruments.

Psychometric properties of the healthful eating belief scales for persons at risk of diabetes

OBJECTIVE

To examine the validity and reliability of Theory of Planned Behavior (TPB) scales for healthful eating for persons at risk for diabetes.

DESIGN

Cross-sectional, using a self-administered questionnaire.

SETTING

Community in the Midwest.

PARTICIPANTS

106 adults who self-identified based on one or more American Diabetes Association diabetes risks.

VARIABLES MEASURED

Behavioral, normative, and control beliefs; and attitude, subjective norm, perceived behavioral control, and intention to eat a healthful diet.

ANALYSIS

Construct validity was assessed with factor analyses and measurement and structural models using structural equation modeling. Reliability of the scales was assessed with Cronbach alpha and a 2-month test-retest.

RESULTS

Factor analysis loadings were greater than .37. Cronbach alphas for the behavioral, normative, and control belief scales were .80, .91, and .84, respectively. The measurement model revealed that the measures were significant estimates for the TPB constructs, and they fit well as indirect measures of attitude, subjective norm, and perceived behavioral control in predicting intention to eat a healthful diet. Test-retest revealed 2-month stability of the scales.

CONCLUSIONS AND IMPLICATIONS

Scales for measuring TPB behavioral, normative, and control beliefs were valid and reliable for use with adults at risk for diabetes. Further examination with minority persons is warranted.