Lydia Kwak

Associations between physical activity, fitness, and academic achievement

OBJECTIVES To explore the associations between objectively assessed intensity levels of physical activity and academic achievement and test whether cardiovascular fitness mediates the association between physical activity and academic achievement. STUDY DESIGN Cross-sectional data were gathered in Swedish 9th-grade students (n = 232; mean age = 16 years; 52% girls). School grades, pubertal phase, skinfold thickness, cardiovascular fitness, and physical activity were measured objectively. Mothers education, family structure, and parental monitoring were self-reported. Data were analyzed with linear regression analyses. RESULTS After controlling for confounding factors, academic achievement was associated with vigorous physical activity in girls (beta = .30, P < .01; explained variance of the model 26%), which remained after inclusion of fitness (beta = .23, P < .05; explained variance 29%). The association was not mediated by fitness. In boys, academic achievement was associated with pubertal phase (beta = .25, P < .05). After inclusion of fitness, it was only associated with fitness (beta = .25, P < .05; explained variance of the model 30%). CONCLUSION In girls, academic achievement was associated with vigorous physical activity and not mediated by fitness, whereas in boys only fitness was associated with academic achievement. Further studies are necessary to investigate the potential longitudinal effect of vigorous physical activity on academic achievement, the role of fitness herein and the implications of these findings for schools.

Equity-specific effects of 26 Dutch obesity-related lifestyle interventions

CONTEXT Reducing health inequalities is a policy priority in many developed countries. Little is known about effective strategies to reduce inequalities in obesity and its underlying behaviors. The goal of the study was to investigate differential effectiveness of interventions aimed at obesity prevention, the promotion of physical activity or a healthy diet by SES. EVIDENCE ACQUISITION Subgroup analyses in 2010 and 2011 of 26 Dutch studies funded by The Netherlands Organization for Health Research and Development after 1990 (n=17) or identified by expert contact (n=9). Methodologic quality and differential effects were synthesized in harvest plots, subdivided by setting, age group, intensity, and time to follow-up. EVIDENCE SYNTHESIS Seven lifestyle interventions were rated more effective and four less effective in groups with high SES; for 15 studies no differential effects could be demonstrated. One study in the healthcare setting showed comparable effects in both socioeconomic groups. The only mass media campaign provided modest evidence for higher effectiveness among those with high SES. Individually tailored and workplace interventions were either more effective in higher-SES groups (n=4) or no differential effects were demonstrated (n=9). School-based studies (n=7) showed mixed results. Two of six community studies provided evidence for better effectiveness in lower-SES groups; none were more effective in higher-SES groups. One high-intensity community-based study provided best evidence for higher effectiveness in low-SES groups. CONCLUSIONS Although for the majority of interventions aimed at obesity prevention, the promotion of physical activity, or a healthy diet, no differential effectiveness could be demonstrated, interventions may widen as well as reduce socioeconomic inequalities in these outcomes. Equity-specific subgroup analyses contribute to needed knowledge about what may work to reduce socioeconomic inequalities in obesity and underlying health behaviors.

A 6 year longitudinal study of accelerometer-measured physical activity and sedentary time in Swedish adults.

OBJECTIVES The aim of this study was to investigate changes over six years in physical activity and sedentary behavior assessed with accelerometry in a representative sample of Swedish adults. DESIGN A longitudinal study over six years. METHODS The cohort consisted of 1172 participants (46% males) in 2002 and 511 participants (46% males) in 2008, of which 478 (45% males) had valid data on both occasions. Mean (SD) age at baseline was 45 (15) years. To analyze changes over time, a mixed linear model for average intensity physical activity (counts/min) and time in sedentary behavior and light- and moderate- or higher-intensity physical activity was conducted, stratified for sex and age, and adjusted for BMI, education, self-rated health and Δ wear time. RESULTS Over a six year period no significant changes were seen in the total cohort for average intensity and time in moderate- or higher intensity physical activity. A significant decrease in average intensity physical activity was found for men (p=0.006) and those aged 60+ years at baseline (p<0.001). A significant increase (26 min/day) for sedentary time in the total cohort (p<0.001) and for time in moderate or higher intensity physical activity among women (p<0.001) and those aged 40-59 years at baseline (p=0.014) was found over the follow-up period. CONCLUSIONS The overall increase in sedentary time and decrease in average physical activity among men and the elderly are of concern, since they might result in an elevated risk of developing chronic diseases.

Examining differences in physical activity levels by employment status and/or job activity level: Gender-specific comparisons between the United States and Sweden

OBJECTIVES The aim of the study was to examine the relationship between employment status and job activity level with physical activity (PA) and sedentary time, stratified by gender and country. DESIGN Cross-sectional study design. METHODS Data from working age adults (18-65 years) from two cross-sectional studies, the Swedish 2001-2002 and 2007-2008 Attitude Behavior and Change Study (ABC; n=1165) and the 2003-2006 US National Health and Nutrition Examination Survey (NHANES; n=4201), were stratified by employment status (employed and not employed) and job activity level (active, sedentary and mixed). PA in counts×min(-1) and time spent in sedentary, low and moderate or higher intensity were measured with accelerometers. Analyses were conducted in 2012-2013. RESULTS In NHANES, the employed had significantly higher counts×min(-1) and spent more time in moderate or higher intensity PA than those not employed. In ABC, no significant differences were observed between employed and unemployed. Adults with active versus sedentary occupations had higher counts×min(-1) and less sedentary time in both the USA and Sweden and in both men and women. For example, counts×min(-1) were 20-40% greater in active versus sedentary jobs. CONCLUSIONS Employment status is related to PA and sedentary time among men and women in the USA but not in Sweden. Among the employed, occupational PA is associated with total PA and sedentary time for both genders and in both countries. Comparisons of PA levels based on objective measurements can refine understanding of country differences in activity.

Promoting Physical Activity and Healthy Dietary Behavior: The Role of the Occupational Health Services

Objective:Conduct a scoping review to identify and map the literature that has evaluated the effects of health promotion interventions aimed at physical activity and/or dietary behavior, implemented by the occupational health services. Methods:A search for peer-reviewed articles was conducted (up to February 2013) through electronic databases, hand searching of key journals, and reference lists. A methodological quality assessment was performed. Results:Fourteen studies were included, describing 10 interventions. The main component was counseling of individuals with known cardiovascular disease risk factors. Intervention effects were reported for dietary behavior, physical activity, sedentary behavior, and biological risk factors. Conclusions:Results are promising, especially with regard to interventions containing counseling targeting individuals at risk. High-quality studies using objective measures to assess behavioral outcomes and the (cost)-effectiveness of interventions containing counseling, PA on prescription, and multilevel interventions are needed.

Role of socio-cultural factors on changes in fitness and adiposity in youth: A 6-year follow-up study

BACKGROUND AND AIMS Optimal cardio-respiratory fitness and adiposity levels are tightly related to health in youth. We analysed changes in fitness and adiposity in young individuals from two countries, and examined the role of maternal education in these changes. METHODS AND RESULTS A 6-year follow-up study was conducted on 483 Estonian children (9 years) and 466 Swedish children (9-10 years) and adolescents (15 years). Fitness was assessed by a maximal bike test, and total and central adiposity were indirectly estimated by skinfolds (Slaughters equation for fat mass) and waist circumference. At follow-up, fitness and adiposity had increased in the children cohort (P ≤ 0.001), while small or no change occurred in the adolescent cohort. In the children cohort, Estonian participants had a lower increase in fitness and a higher increase in adiposity (total and central) than Swedish participants. Higher maternal education increased the odds of remaining fit (top quartile) by half and reduced the risk of remaining fat (top quartile) by half; odds ratios = 1.56 (1.00-2.43), 0.50 (0.32-0.77) and 0.61 (0.39-0.94) for fitness, total and central adiposity, respectively. CONCLUSIONS Our data suggest that the socioeconomic situation of a country might influence key cardiovascular risk factors (fitness and adiposity), being at higher risk for a low-middle income country (Estonia) than a higher income country (Sweden). The findings stress the role of socioeconomic status, particularly maternal education, in the maintenance of healthy fitness and adiposity levels from childhood into later life. Preventive efforts have to be taken from early age.

Replacing sedentary time with physical activity: a 15-year follow-up of mortality in a national cohort

Background Sedentary behavior is associated with health risks in adults. The potential benefits of reducing sedentary time may be dependent not only on decrease per se, but also on the type of activity it replaces. Few longitudinal studies have investigated the effects on mortality when replacing objectively assessed sedentary time with another physical activity (PA) behavior. Objective To investigate the effects of replacing objectively assessed sedentary time with time in light-intensity PA or moderate-vigorous PA (MVPA) on all-cause mortality, cardiovascular disease (CVD) mortality or cancer mortality in a cohort with 15 years follow-up time. Methods In total, 851 women and men from the population-based Sweden Attitude Behaviour and Change study were included. Time spent sedentary, in light-intensity PA and in MVPA were assessed using an Actigraph 7164 accelerometer. Mortality data were obtained from Swedish registers. Cox proportional hazards models estimated hazard ratios (HR) of mortality with 95% confidence intervals (CI) and isotemporal substitution models were used to estimate the effect of replacing sedentary behavior with PA for the same amount of time. Results Over a follow-up of 14.2 years (SD 1.9) with 12,117 person-years at risk, 79 deaths occurred, 24 deaths from CVD, 27 from cancer, and 28 from other causes. Replacing 30 minutes/day of sedentary time with light-intensity PA was associated with significant reduction in all-cause mortality risk (HR: 0.89, 95% CI: 0.81–0.98) and CVD mortality risk (HR: 0.76, 95% CI: 0.63–0.92). Replacing 10 minutes of sedentary time with MVPA was associated with reduction in CVD mortality risk (HR: 0.62, 95% CI: 0.42–0.91). No statistically significant reductions were found for cancer mortality. Conclusion This statistical modelling study suggests that replacing sedentary time with light-intensity PA could have beneficial effect on both all-cause mortality and CVD mortality. Replacing sedentary time with MVPA could reduce CVD mortality.

What incentives influence employers to engage in workplace health interventions

BackgroundTo achieve a sustainable working life it is important to know more about what could encourage employers to increase the use of preventive and health promotive interventions. The objective of the study is to explore and describe the employer perspective regarding what incentives influence their use of preventive and health promotive workplace interventions.MethodSemi-structured focus group interviews were carried out with 20 representatives from 19 employers across Sweden. The economic sectors represented were municipalities, government agencies, defence, educational, research, and development institutions, health care, manufacturing, agriculture and commercial services. The interviews were transcribed verbatim and the data were analysed using latent content analysis.ResultsVarious incentives were identified in the analysis, namely: “law and provisions”, “consequences for the workplace”, “knowledge of worker health and workplace health interventions”, “characteristics of the intervention”, “communication and collaboration with the provider”. The incentives seemed to influence the decision-making in parallel with each other and were not only related to positive incentives for engaging in workplace health interventions, but also to disincentives.ConclusionsThis study suggests that the decision to engage in workplace health interventions was influenced by several incentives. There are those incentives that lead to a desire to engage in a workplace health intervention, others pertain to aspects more related to the intervention use, such as the characteristics of the employer, the provider and the intervention. It is important to take all incentives into consideration when trying to understand the decision-making process for workplace health interventions and to bridge the gap between what is produced through research and what is used in practice.

Psychosocial Determinants and Perceived Environmental Barriers as Mediators of the Effectiveness of a Web-Based Tailored Intervention Promoting Physical Activity in Adolescents: The HELENA Activ-O-Meter

BACKGROUND The aim was to examine if psychosocial determinants (attitudes, self-efficacy, social support from a sports partner) and perceived environmental barriers (PEB) of physical activity (PA) mediated the effect of a 3-month Internet-based intervention on PA in European adolescents. METHODS A sample of 536 adolescents (51% boys) aged 12-17 years were randomly assigned to intervention or control condition. Questionnaires were used to assess different PA behaviors, psychosocial determinants and PEB at baseline and at 3-month follow-up. Mediating effects were assessed with the bootstrapping method. RESULTS PEB regarding neighborhood safety mediated the effect of the intervention on all PA indices. PEB regarding sports facilities availability at neighborhood and PEB regarding sport-related facilities availability at school mediated the effect of the intervention on moderate to vigorous PA (MVPA) and moderate PA (in leisure time and at school, respectively). Social support from a sports partner suppressed the effect of the intervention on vigorous PA and MVPA. No other factor had a mediation effect. CONCLUSIONS All PEB measures appear to mediate PA behaviors of different intensities and in different contexts. Interventions promoting PA in adolescents should also focus on improving the targeted PEB as mediators of engagement in PA to bring the desired effects in actual behaviors.

Work-related stress assessed by a text message single-item stress question

Abstract Background Given the prevalence of work stress-related ill-health in the Western world, it is important to find cost-effective, easy-to-use and valid measures which can be used both in research and in practice. Aims To examine the validity and reliability of the single-item stress question (SISQ), distributed weekly by short message service (SMS) and used for measurement of work-related stress. Methods The convergent validity was assessed through associations between the SISQ and subscales of the Job Demand–Control–Support model, the Effort–Reward Imbalance model and scales measuring depression, exhaustion and sleep. The predictive validity was assessed using SISQ data collected through SMS. The reliability was analysed by the test–retest procedure. Results Correlations between the SISQ and all the subscales except for job strain and esteem reward were significant, ranging from −0.186 to 0.627. The SISQ could also predict sick leave, depression and exhaustion at 12-month follow-up. The analysis on reliability revealed a satisfactory stability with a weighted kappa between 0.804 and 0.868. Conclusions The SISQ, administered through SMS, can be used for the screening of stress levels in a working population.