Trajectories of objectively measured physical activity and childhood overweight: longitudinal analysis of the IDEFICS/I.Family cohort.

BACKGROUND: Since only few longitudinal studies with appropriate study designs investigated the relationship between objectively measured physical activity (PA) and overweight, the degree PA can prevent excess weight gain in children, remains unclear. Moreover, evidence is limited on how childhood overweight determines PA during childhood. Therefore, we analyzed longitudinal trajectories of objectively measured PA and their bi-directional association with weight trajectories of children at 2- and 6-year follow-ups. METHODS: Longitudinal data of three subsequent measurements from the IDEFICS/I.Family cohort study were used to analyze the bi-directional association between moderate-to-vigorous PA (MVPA) and weight status by means of multilevel regression models. Analyses comprised 3393 (2-year follow-up) and 1899 (6-year follow-up) children aged 2-15.9 years from eight European countries with valid accelerometer data and body mass index (BMI) measurements. For categorized analyses, children's weight status was categorized as normal weight or overweight (cutoff: 90th percentile of BMI) and children's PA as (in-) sufficiently active (cutoffs: 30, 45 and 60 min of MVPA per day). RESULTS: Children engaging in at least 60 min MVPA daily at baseline and follow-ups had a lower odds of becoming overweight (odds ratio [OR] at 2-year follow-up: 0.546, 95% CI: 0.378, 0.789 and 6-year follow-up: 0.393, 95% CI: 0.242, 0.638), compared to less active children. Similar associations were found for 45 min MVPA daily. On the other side, children who became overweight had the lowest odds to achieve 45 or 60 min MVPA daily (ORs: 0.459 to 0.634), compared to normal weight children. CONCLUSIONS: Bi-directional associations between MVPA and weight status were observed. In summary, at least 60 min MVPA are still recommended for the prevention of childhood overweight. To prevent excess weight gain, 45 min MVPA per day also showed preventive effects.

Effects of Installing Height-Adjustable Standing Desks on Daily and Domain-Specific Duration of Standing, Sitting, and Stepping in 3rd Grade Primary School Children.

Background: Aim of this intervention study was to evaluate whether availability of standing desks in classrooms may reduce sitting time and enhance standing and stepping time during lessons and breaks. Further, we evaluated if differences in standing desk use differed by physical fitness (PF) levels of children. Methods: To assess sitting, standing and stepping during a typical school week in 3rd grade primary school children (N = 52), activPAL monitors were used at baseline: T0, 1st follow-up: T1 and 2nd follow-up: T2. At baseline, PF was measured using the standing long jump and the 6-min jog-walk to assign children as having low PF (LPF) or high PF (HPF). Standing desks were assigned randomly to intervention and control groups at T1 (group 1) and T2 (group 2) with a cross-over design. Changes of sitting, standing and stepping were analyzed to investigate intervention effects at follow-up, using linear mixed models. Results: At baseline, children spent about 60 and 30% of time sitting during lessons and breaks, respectively. After installing standing desks (T1), significantly lower proportions of sitting were observed in the intervention group 1 [-13.1%, 95%-CI: (-20.5; -5.72)] and the control group 2 [-9.78%, 95%-CI: (-17.3; -2.28)]. Compared to the baseline measurement (T0), lower proportions of sitting were particularly expressed during school breaks in group 1 and 2 after intervention in T1 [group 1: -10.3%, 95%-CI: (-16.4; -4.25)] or in T2 [group 2: -8.59%, 95%-CI: (-15.2; -1.94)]. In general, children with higher physical fitness were less sedentary and more active, but intervention effects did not differ by fitness levels. Conclusion: Standing desks provide an opportunity to reduce sedentary time during lessons and breaks at school in primary school children, but do not directly increase PA of high intensity such as stepping. Future studies should consider potential bandwagon effects caused by structural interventions.

Variations in accelerometry measured physical activity and sedentary time across Europe - harmonized analyses of 47,497 children and adolescents.

BACKGROUND: Levels of physical activity and variation in physical activity and sedentary time by place and person in European children and adolescents are largely unknown. The objective of the study was to assess the variations in objectively measured physical activity and sedentary time in children and adolescents across Europe. METHODS: Six databases were systematically searched to identify pan-European and national data sets on physical activity and sedentary time assessed by the same accelerometer in children (2 to 9.9 years) and adolescents (≥10 to 18 years). We harmonized individual-level data by reprocessing hip-worn raw accelerometer data files from 30 different studies conducted between 1997 and 2014, representing 47,497 individuals (2-18 years) from 18 different European countries. RESULTS: Overall, a maximum of 29% (95% CI: 25, 33) of children and 29% (95% CI: 25, 32) of adolescents were categorized as sufficiently physically active. We observed substantial country- and region-specific differences in physical activity and sedentary time, with lower physical activity levels and prevalence estimates in Southern European countries. Boys were more active and less sedentary in all age-categories. The onset of age-related lowering or leveling-off of physical activity and increase in sedentary time seems to become apparent at around 6 to 7 years of age. CONCLUSIONS: Two third of European children and adolescents are not sufficiently active. Our findings suggest substantial gender-, country- and region-specific differences in physical activity. These results should encourage policymakers, governments, and local and national stakeholders to take action to facilitate an increase in the physical activity levels of young people across Europe.

[Measuring physical fitness in the German National Cohort-methods, quality assurance, and first descriptive results]. / Messung der körperlichen Fitness in der NAKO Gesundheitsstudie ­ Methoden, Qualitätssicherung und erste deskriptive Ergebnisse.

Physical fitness is defined as an individual's ability to be physically active. The main components are cardiorespiratory fitness (CRF), muscle strength, and flexibility. Regardless of physical activity level, physical fitness is an important determinant of morbidity and mortality.The aim of the current study was to describe the physical fitness assessment methodology in the German National Cohort (NAKO) and to present initial descriptive results in a subsample of the cohort.In the NAKO, hand grip strength (GS) and CRF as physical fitness components were assessed at baseline using a hand dynamometer and a submaximal bicycle ergometer test, respectively. Maximum oxygen uptake (VO2max) was estimated as a result of the bicycle ergometer test. The results of a total of 99,068 GS measurements and 3094 CRF measurements are based on a data set at halftime of the NAKO baseline survey (age 20-73 years, 47% men).Males showed higher values of physical fitness compared to women (males: GS = 47.8 kg, VO2max = 36.4 ml·min-1 · kg-1; females: GS = 29.9 kg, VO2max = 32.3 ml · min-1 · kg-1). GS declined from the age of 50 onwards, whereas VO2max levels decreased continuously between the age groups of 20-29 and ≥60 years. GS and VO2max showed a linear positive association after adjustment for body weight (males ß = 0.21; females ß = 0.35).These results indicate that the physical fitness measured in the NAKO are comparable to other population-based studies. Future analyses in this study will focus on examining the independent relations of GS and CRF with risk of morbidity and mortality.

[Physical activity in the German National Cohort (NAKO): use of multiple assessment tools and initial results]. / Körperliche Aktivität in der NAKO Gesundheitsstudie: erste Ergebnisse des multimodalen Erhebungskonzepts.

BACKGROUND: Physical activity is a complex behavior that is difficult to measure validly and reliably in large, population-based studies. Data on physical activity are available for the initial 100,000 participants of the German National Cohort. OBJECTIVES: To describe the baseline physical activity assessment in the cohort and to present initial descriptive results. MATERIAL AND METHODS: Physical activity was assessed using a combination of tools, including two self-administered questionnaires, the Questionnaire on Annual Physical Activity Pattern (QUAP) and the Global Physical Activity Questionnaire (GPAQ); a computer-based 24­h physical activity recall (cpar24); and 7­day accelerometry (Actigraph GT3X/+; ActiGraph, Pensacola, FL, USA). RESULTS: The availability of data varied between assessment instruments (QUAP: n = 16,372; GPAQ: n = 90,900; cpar24: n = 23,989; accelerometry: n = 35,218). Analyses across measurement tools showed that on average, women spent 75 to 216 min/d, and men spent 73 to 224 min/d in moderate or higher intensity total physical activity. Persons aged 20-39 years spent 66 to 200 min/d, and persons aged 40-69 years spent 78 to 244 min/d in moderate or higher intensity total physical activity. CONCLUSIONS: Initial baseline analyses of physical activity in this cohort show the value of using a combination of questionnaires, 24­h recalls, and a movement sensor. The comprehensive data collection represents a valuable resource for future analyses and will improve our understanding of the association between physical activity and disease prevention.

Sports Contribute to Total Moderate to Vigorous Physical Activity in School Children.

INTRODUCTION: A third of all children spend at least 60 min·d in moderate to vigorous physical activity (MVPA) as recommended by the World Health Organization. We investigated the distribution of objectively measured physical activity (PA) intensities achieved by schoolchildren during physical education (PE) and organized youth sports (OYS) and the contribution of PE and OYS to the achievement of the PA recommendations. METHODS: In two surveys, PA of 396 children was measured using accelerometry during typical school weeks. Proportions (%) of sedentary behavior, light PA, and MVPA per day and particularly during sports were assessed in children 6-17 yr old. Adjusted odds ratios (AOR) were calculated to analyze the association between frequency (d·wk) and duration (min·wk) of PE and OYS and meeting the PA recommendations. RESULTS: Average proportions of MVPA during PE and OYS ranged between 15% and 31%. Between 68% and 74% of children (6-10 yr) and between 27% and 37% of adolescents (11-17 yr) met the PA recommendations. In both age-groups, PE and OYS on at least 2 d·wk were both significantly associated with meeting the PA recommendations (AOR for PE = 3.60, 95% confidence interval [CI] = 2.05-6.31; AOR for OYS = 3.83, 95% CI = 2.09-6.99), compared with no PE or no OYS in that week. Likewise, significant AOR values were found for >90 min of PE per week (AOR = 3.48, 95% CI = 2.03-5.98) and >120 min of OYS per week (AOR = 3.72, 95% CI = 2.01-6.89), compared with no PE or no OYS in that week, respectively. CONCLUSION: Schoolchildren spent less than one-third of PE and OYS in MVPA. PE and OYS were found to support children and adolescents to engage sufficiently in MVPA as recommended by the World Health Organization.

Food and beverage intakes according to physical activity levels in European children: the IDEFICS (Identification and prevention of Dietary and lifestyle induced health EFfects In Children and infantS) study.

OBJECTIVE: Physical activity (PA) levels and dietary habits are considered some of the most important factors associated with obesity. The present study aimed to examine the association between PA level and food and beverage consumption in European children (2-10 years old).Design/Setting/SubjectsA sample of 7229 children (49·0 % girls) from eight European countries participating in the IDEFICS (Identification and prevention of Dietary and lifestyle induced health EFfects In Children and infantS) study was included. Moderate-to-vigorous PA (MVPA) was assessed objectively with accelerometers. FFQ was used to register dietary habits. ANCOVA and binary logistic regression were applied. RESULTS: Boys who spent less time in MVPA reported lower consumption of vegetables, fruits, cereals, yoghurt, milk, bread, pasta, candies and sugar-sweetened beverages (SSB) than boys who spent more time in MVPA (P<0·05). Moreover, boys who spent less time in MVPA were more likely to consume fast foods and water than those in the highest MVPA tertile (P<0·05). Girls who spent less time in MVPA reported lower consumption frequencies of vegetables, pasta, bread, yoghurt, candies, jam/honey and SSB than girls in the highest MVPA tertile (P<0·05). Also, girls in the lowest MVPA tertile were more likely to consume fast foods and water than those with high levels of MVPA (P<0·05). CONCLUSIONS: Food intake among European children varied with different levels of daily MVPA. Low time spent in MVPA was associated with lowest consumption of both high- and low-energy-dense foods and high fast-food consumption.

Social vulnerability as a predictor of physical activity and screen time in European children.

OBJECTIVES: To examine associations between social vulnerabilities and meeting physical activity (PA) and screen time (ST) recommendations during a 2-year follow-up. METHODS: 13,891 children aged 2.0 to  < 9.9 from eight European countries were assessed at baseline and 8482 children at follow-up. Children's sports club membership, PA and ST were collected via parental questionnaires. Moderate-to-vigorous physical activity (MVPA) was objectively assessed with accelerometers. Performing at least 1 h of MVPA daily and spending less than 2 h of ST defined physically active and non-sedentary children, respectively. Vulnerable groups were defined at baseline as children whose parents had minimal social networks, from non-traditional families, with migrant origin or with unemployed parents. Logistic mixed-effects analyses were performed adjusting for classical socioeconomic indicators. RESULTS: Children whose parents had minimal social networks had a higher risk of non-compliance with PA recommendations (subjectively assessed) at baseline. Migrants and children with unemployed parents had longer ST. All vulnerable groups were less likely to be sports club members. CONCLUSIONS: Migrants and children with unemployed parents are at risk for excessive ST and all vulnerable groups have lower odds of being sports club members.

Domain-Specific Self-Reported and Objectively Measured Physical Activity in Children.

Little is known about the extent that different domains contribute to total sedentary (SED), light (LPA) and moderate-to-vigorous physical activity (MVPA). We aimed to identify domain-specific physical activity (PA) patterns in school-aged children who were assessed by questionnaire and accelerometry. For the study, 298 German school children and adolescents aged 6-17 years wore an accelerometer for one week and completed a PA recall-questionnaire for the same period. Spearman coefficients (r) were used to evaluate the agreement between self-reported and objectively measured PA in five domains (transport, school hours, physical education, leisure-time, organized sports activities). School hours mainly contributed to the total objectively measured SED, LPA and MVPA (55%, 53% and 46%, respectively), whilst sports activities contributed only 24% to total MVPA. Compared to accelerometry, the proportion of self-reported LPA and MVPA during school hours was substantially underestimated but overestimated during leisure-time. The agreement of self-reported and objectively measured PA was low for total LPA (r = 0.09, 95% CI (confidence interval): -0.03-0.20) and total MVPA (r = 0.21, 95% CI: 0.10-0.32), while moderate agreement was only found for total SED (r = 0.44, 95% CI: 0.34-0.53), LPA during transport (r = 0.59; 95% CI: 0.49-0.67) and MVPA during organized sports activities (r = 0.54; 95% CI: 0.38-0.67). Since school hours mainly contribute to total SED, LPA and MVPA and self-reported LPA and MVPA during school were importantly underestimated compared to objectively measured LPA and MVPA, the application of objective measurements is compulsory to characterize the entire activity pattern of school-aged children.

Determinant factors of physical fitness in European children.

OBJECTIVES: This study was designed to explore the determinants of physical fitness in European children aged 6-11 years, cross-sectionally and longitudinally. METHODS: There were sufficient data on 4903 children (50.6 % girls) on measured physical fitness (cardio-respiratory, muscular strength, flexibility, balance, and speed) and possible determinants related to child characteristics, child lifestyle and parental factors. Multivariate and mixed linear regression models were conducted. RESULTS: Age, sex, children's BMI and physical activity were independent and strong determinants of children's fitness. Significant but small effects were found for low maternal BMI, high psychosocial well-being and fruit and vegetable intake as protective determinants. Sleep duration, breakfast intake, parental age and education and paternal BMI did not have a consistently significant effect on physical fitness. The role of determinants depended on children's sex and the specific PF component. Longitudinal analyses especially highlighted the importance of child's BMI as physical fitness determinant, independent of physical activity. CONCLUSIONS: BMI together with physical activity, diet and psychosocial factors are modifiable targets to enhance physical fitness. This calls for policy approaches that combine these factors in a systematic way.