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An association between distance to a green space and health and health-related quality of life was found. Further, the results indicate awareness among Danes that green spaces may be of importance in managing stress and that green spaces may play an important role as health-promoting environments.

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Purpose Understanding factors that influence accurate assessment of physical activity (PA) and sedentary behavior (SB) is important to measurement development, epidemiologic studies, and interventions. This study examined agreement between self-reported (International Physical Activity Questionnaire – Long Form, IPAQ-LF) and accelerometry-based estimates of PA and SB across six countries, and identified correlates of between-method agreement. Methods Self-report and objective (accelerometry-based) PA and SB data were collected in 2002-2011 from 3,865 adult participants in eight cities from six countries (Belgium, Czech Republic, Denmark, Spain, UK, and USA). Between-method relative agreement (correlation) and absolute disagreement (mean difference between conceptually- and intensity-matched IPAQ-LF and accelerometry-based PA and SB variables) were estimated. Also, socio-demographic characteristics and PA patterns were examined as correlates of between-method agreement. Results Observed relative agreement (relationships of IPAQ-LF with accelerometry-based PA and SB variables) was small to moderate (r=0.05-0.37) and was moderated by socio-demographic (age, sex, weight status, education) and behavioral (PA-types) factors. The absolute disagreement was large, with participants self-reporting higher PA intensity and total time in moderate-to-vigorous PA than accelerometry. Also, self-reported sitting time was lower than accelerometry-based sedentary behavior. After adjusting for socio-demographic and behavioral factors, the absolute disagreement between pairs of IPAQ-LF and accelerometry-based PA variables remained significantly different across cities/countries. Conclusions Present findings suggest systematic cultural and/or linguistic and socio-demographic differences in absolute agreement between the IPAQ-LF and accelerometry-based PA and SB variables. These results have implications for the interpretation of international PA and SB data and correlates/determinants studies. They call for further efforts to improve such measures.

BackgroundAccelerometry is increasingly being recognized as an accurate and reliable method to assess free-living physical activity (PA) in children and adolescents. However, accelerometer data reduction criteria remain inconsistent, and the consequences of excluding participants in for example intervention studies are not well described. In this study, we investigated how different data reduction criteria changed the composition of the adolescent population retained in accelerometer data analysis.MethodsAccelerometer data (Actigraph GT3X), anthropometric measures and survey data were obtained from 1348 adolescents aged 11–14 years enrolled in the Danish SPACE for physical activity study. Accelerometer data were analysed using different settings for each of the three key data reduction criteria: (1) number of valid days; (2) daily wear time; and (3) non-wear time. The effects of the selected setting on sample retention and PA counts were investigated and compared. Ordinal logistic regression and multilevel mixed-effect linear regression models were used to analyse the impact of differing non-wear time definitions in different subgroups defined by body mass index, age, sex, and self-reported PA and sedentary levels.ResultsIncreasing the minimum requirements for daily wear time and the number of valid days and applying shorter non-wear definitions, resulted in fewer adolescents retained in the dataset. Moreover, the different settings for non-wear time significantly influenced which participants would be retained in the accelerometer data analyses. Adolescents with a higher BMI (OR:0.93, CI:0.87-0.98, p=0.015) and older adolescents (OR:0.68, CI:0.49-0.95, p=0.025) were more likely to be excluded from analysis using 10 minutes of non-wear compared to longer non-wear time periods. Overweight and older adolescents accumulated more daily non-wear time if the non-wear time setting was short, and the relative difference between groups changed depending on the non-wear setting. Overweight and older adolescents did also accumulate more sedentary time, but this was not significant correlated to the non-wear setting used.ConclusionsEven small differences in accelerometer data reduction criteria can have substantial impact on sample size and PA and sedentary outcomes. This study highlighted the risk of introducing bias with more overweight and older adolescents excluded from the analysis when using short non-wear time definitions.