Elling Bere and Lars Bo Andersen
Søren Brage, Niels Wedderkopp, Lars Bo Andersen and Karsten Froberg
Four Computer Science and Applications (CSA, Model 7164) accelerometers were validated against speed and heart rate in a field trial, consisting of two walking and two preset running speeds, and 3 min of running at freely chosen speeds. Fifteen children (9–11 years) were recruited from a suburban school in Denmark. Mean CSA output was calculated and converted to acceleration by calibration to sinusoidal accelerations in a mechanical setup, the latter variable being independent of frequency-based filtering. Mean CSA output and estimated acceleration both correlated significantly with speed (r 2 = 0.55 and r 2 = 0.76, respectively) and heart rate (r 2 = 0.60 and r 2 = 0.81, respectively), controlled for gender. ANOVA post hoc test failed to show significant differences in accelerometer output between running speeds. Inter-individual variability of CSA output and acceleration could not be explained by differences in step frequency in walking but running values correlated significantly with step frequency (r = −0.86 and r = −0.47 for CSA output and acceleration, respectively). Conversion of CSA output to average acceleration provides more precise estimates of intensity with less inter-individual variability than raw CSA output. Different running intensities, however, are generally not well differentiated with vertical accelerometry.
Line Anita Bjørkelund Børrestad, Lars Østergaard, Lars Bo Andersen and Elling Bere
To provide more accurate assessment of commuting behavior and potential health effect, it is important to have accurate methods. Therefore, the current study aimed to a) compare questionnaire reported mode of commuting with objectively measured data from accelerometer and cycle computer, b) compare moderate vigorous physical activity (MVPA) among children cycling vs. walking to school, and c) thus calculate possible underestimated MVPA, when using accelerometers to measure commuter cycling.
A total of 78 children, average age 11.4 (SD = 0.5), participated in the study. Physical activity was measured with cycle computers and accelerometers for 4 days. Mode of commuting and demographic information was self-reported in a questionnaire.
Children who reported to cycle to school spent significantly more time cycling than those who walked to school, 53.6 (SD = ± 33.9) minutes per day vs. 25.5 (SD = ± 24.6) minutes per day (P = .002) (ie, showing that MVPA, measured by accelerometers, underestimated 28.1 minutes per day among children cycling to school vs. those not cycling to school).
To provide more accurate assessment of active commuting in children and adolescents future studies should incorporate multiple methodologies such as global position systems (GPS), accelerometers, cycle computers, and self-reported measurements.
Niels Wedderkopp, Karsten Froberg, Henrik Steen Hansen, Chris Riddoch and Lars Bo Andersen
The aim of this study was to assess the association between physical fitness and clustering of cardiovascular disease (CVD) risk factors in boys and girls aged 9 years (children) and 15 years (adolescents). Subjects were 1020 randomly selected children and adolescents. Cardiorespiratory fitness was assessed by a maximal cycle ergometer test. A subject was defined as having a risk factor if he/she belonged to the upper quartile of risk within age and gender group for that risk factor. Clustering was analysed in relation to being at risk in a) three or more and b) four or more of five possible risk factors (TC:HDL ratio, insulin:glucose ratio, triglyceride, systolic BP and sum of four skinfolds. Physical fitness was weakly related to single CVD risk factors except sum of skinfolds where the relationship was strong. Low fitness increased the risk of having three or more CVD risk factors with odds ratios (OR) using the upper quartile of fitness as reference of 1.9 (95% CI: 0.8–4.1), 3.0 (95% CI: 1.4–6.3) and 11.4 (95% CI: 5.7–22.9), respectively. Using the criterion of four or more risk factors, an OR of 24.1 (95% CI 5.7–101.1) was found in the low fit group.
Stig Eiberg, Henriette Hasselstrom, Vivian Grønfeldt, Karsten Froberg, Ashley Cooper and Lars Bo Andersen
The aim of this study was to investigate whether risk factors for cardiovascular disease cluster in 6- to 7-year-old children and whether low physical fitness is a predictor of risk factor clustering. The study included 369 boys (6.8 ± 0.4 years) and 327 girls (6.7 ± 0.4 years). VO2max was directly measured during a treadmill test. The ratio of total cholesterol to high-density cholesterol, triglyceride levels, the ratio of insulin to glucose, systolic blood pressure, and the sum of four skinfolds were selected as risk factors. A child was considered at risk for individual factors if he or she had values in the least favorable quartile. The number of children with more than three cardiovascular disease cluster risk factors was not significantly different from a binominal distribution. This lack of clustering could be a result of the fact that these young children have not yet developed insulin resistance. Children in the lowest quartile of fitness had an odds ratio of 2.1 (CI: 1.0–4.4) for having three or more risk factors compared with the most fit. This is interesting with regard to prevention because it indicates that an intervention involving increased physical activity might postpone or even prevent the development of risk factors.
Russell Jago, Karsten Froberg, Ashley R. Cooper, Stig Eiberg and Lars Bo Andersen
It is not clear the extent to which change in adiposity and cardiovascular fitness (CRF) during early childhood are associated with change in cardiovascular risk factors or if associations are independent or interactive.
383 Danish children were examined at ages 6 and 9. CRF, sum of skinfolds (SSF), and blood pressure were assessed. Fasting blood samples were used to calculate total cholesterol (TC), high and low density lipoprotein cholesterol (HDL-C & LDL-C), triglycerides, insulin, glucose, and HOMA-IR. Regression models examined whether CRF change or SSF change were independently or interactively associated with risk variables.
Change in SSF was independently associated with change in TC (z =4.83, P < .0o1), LDL-C (z =4.38, P < .001), systolic (z = 3.45, P < .001), and diastolic (z = 2.45, P = .014) blood pressure. CRF change was independently associated with change in TC (z =-3.86, P < .001), HDL-C (z =3.85, P < .001), and systolic blood pressure (z = 2.06, P = .040).
Change in fitness and adiposity were independently associated with the development of cardiovascular risk factors among young children suggesting a need to increase CRF and prevent weight gain early during development to improve cardiovascular health.
Rodrigo Antunes Lima, Karin A. Pfeiffer, Niels Christian Møller, Lars Bo Andersen and Anna Bugge
Background: To analyze the longitudinal association between academic performance and moderate to vigorous physical activity (MVPA), vigorous physical activity (VPA), and sedentary (SED) in a 3-year longitudinal study. A secondary aim was to determine whether MVPA and VPA were indirectly related with academic performance via waist circumference (WC). Methods: Physical activity (PA) and SED were measured by accelerometers. Academic performance was assessed by national tests in Danish and Math. Structural equation modeling was performed to evaluate whether MVPA, VPA, and SED were associated with academic performance and the potential PA–academic performance indirect relationship via WC. Results: MVPA and VPA were associated with academic performance, mediated via WC (β = 0.036; 95% confidence interval [CI], 0.002 to 0.070 and β = 0.096; 95% CI, 0.027 to 0.164, respectively). SED was directly associated with academic performance (β = 0.124; 95% CI, 0.030 to 0.217, MVPA model and β = 0.132; 95% CI, 0.044 to 0.221, VPA model). WC was negatively associated with academic performance. Conclusions: Both PA and SED time were positively associated with academic performance. Based on this, PA should be encouraged in children and youth not only to promote physical health but also to promote academic performance. Future studies should distinguish between school-related SED and other SED activities and their relationship with academic performance.
Glen Nielsen, Anna Bugge, Bianca Hermansen, Jesper Svensson and Lars Bo Andersen
This study investigates the influence of school playground facilities on children’s daily physical activity.
Participants were 594 school children measured at preschool (age 6 to 7 years) and 3 years later in third grade (518 children age 9 to 10 years) from 18 schools in 2 suburban municipalities in Denmark. Physical activity data were obtained using accelerometers. These were related to the number of permanent play facilities in school grounds and the school playground area (m2).
The number of play facilities in the school grounds was positively associated with all measures of children’s activity. In preschool every 10 additional play facilities the children had access to was associated with an increase in the average accelerometer counts of 14% (r = .273, P < .001) in school time and 6.9% (r = .195, P < .001) overall. For the children in third grade, access to 10 additional play facilities was associated with an increase in school time activity level of 26% (r = .364, P < .001) and an increase in overall activity level of 9.4% (r = .211, P < .001). School playground area did not affect activity levels independently of the number of permanent play facilities.
Increasing the number of play facilities in primary school playgrounds may increase the level of children’s daily physical activity.
Lars Bo Andersen, Niels Wedderkopp, Peter Kristensen, Niels Christian Moller, Karsten Froberg and Ashley R. Cooper
Cycling to school may potentially increase physical activity level in sedentary children. Transport to school occur twice a day and could improve cardiovascular health in children. Commuter cycling is associated with lower mortality and cardiovascular disease rate in adults, but limited evidence exists in children.
Participants were 334 children (age 9.7 ± 0.5 years) who were followed up 6 years later. Mode of travel to school was investigated by questionnaire. Cardiovascular (CVD) risk factors were compared by mode of travel to school both at baseline and at follow up and for subjects who changed mode of transportation. No difference was found between walkers and passive travelers, and these groups were merged in the analysis.
A consistent pattern of better CVD risk factor profile in commuter cyclists compared with children using other means of transport was found. Participants, who did not cycle to school at baseline, and who had changed to cycling at follow up, were fitter, had better cholesterol/HDL ratio, better glucose metabolism, and a lower composite CVD risk factor score than those who did not cycle at either time point.
Cycling to school may contribute to a better cardiovascular risk factor profile in young people.
Rodrigo Antunes Lima, Lisbeth Runge Larsen, Anna Bugge and Lars Bo Andersen
Purpose: The current investigation aimed to investigate the longitudinal association between physical fitness and academic performance over 3 years in adolescents. A secondary aim was to determine to what extent waist circumference mediated the association between physical fitness and academic performance. Methods: For the current study, 1020 students from first grade [mean age: 7.87 (0.34) y] to fifth grade [mean age: 11.87 (0.37) y] were monitored annually for 3 years (2010–2013). Physical fitness was assessed using the Andersen test, 5 × 5-m shuttle run, jump height, and grip strength tests and by constructing a composite score combining all 4 fitness tests. Academic performance was assessed by national standardized tests in Danish language and math. Generalized structural equation modeling was used to evaluate the relationships between these variables. Results: The Andersen test (standardized β = 0.15 SD), shuttle run (β = −0.18 SD), jump height (β = 0.10 SD), and the fitness composite score (β = 0.23 SD) were positively associated with academic performance over 3 years. In addition, waist circumference partially mediated the association between physical fitness and academic performance. Conclusion: Thus, physical fitness abilities should be stimulated during childhood and early adolescence because of their positive association with academic performance.