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.
Søren Brage, Niels Wedderkopp, Lars Bo Andersen and Karsten Froberg
Jakob Tarp, Anna Bugge, Niels Christian Møller, Heidi Klakk, Christina Trifonov Rexen, Anders Grøntved and Niels Wedderkopp
Background: The role of muscle fitness in controlling cardiometabolic risk factors during childhood is incompletely understood. Methods: A prospective observational design including 6- to 11-year-old children (n = 512) was used to study associations between 1.5-year changes in handgrip strength, standing vertical jump displacement, the short shuttle run, and a composite of these with changes in composite and single cardiometabolic risk markers. The authors modeled sequential mixed linear regressions controlling for changes in cardiorespiratory fitness, waist circumference, and other putative confounding variables. Results: Statistically significant associations, standardized beta (95% confidence intervals), were observed between changes in composite muscle fitness −0.19 (−0.30 to −0.07), muscular strength −0.15 (−0.25 to −0.06), and agility 0.14 (0.04 to 0.23), but not muscular power −0.06 (−0.14 to 0.03) with changes in the composite risk score. In sex-stratified analysis, associations were robust in girls, but not in boys. Control for changes in cardiorespiratory fitness and waist circumference greatly attenuated associations. Changes in muscle fitness were strongly associated with changes in waist circumference in both girls −0.21 (−0.37 to −0.05) and boys −0.23 (−0.35 to −0.11) after controlling for cardiorespiratory fitness. Conclusions: Our data support a unique role of muscle fitness in the promotion of metabolic health and prevention of excess adipose tissue accumulation in children.
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.
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.
Alison M. McMinn, Esther M.F. van Sluijs, Niels Wedderkopp, Karsten Froberg and Simon J. Griffin
Cross-sectional associations between sociocultural factors and objectively-measured physical activity in a sample of 397 children (aged 9) and 213 adolescents (aged 15) were investigated. Associations with children’s physical activity were found for mothers’ physical activity (β=80,p < .01), parental participation (β=67,p = .01), mother’s age (β=−8,p < .01) and, in girls, fathers’ physical activity (β=73, p = .045; R2 for final model: 10.6%). No sociocultural factors were significantly associated with adolescents’ physical activity. Parental factors might be important targets for interventions to increase children’s physical activity but other factors may have greater influence. For adolescents’ physical activity, factors from other domains may be more important to target.
Chris Riddoch, Dawn Edwards, Angie Page, Karsten Froberg, Sigmund A. Anderssen, Niels Wedderkopp, Søren Brage, Ashley R. Cooper, Luis B. Sardinha, Maarike Harro, Lena Klasson-Heggebø, Willem van Mechelen, Colin Boreham, Ulf Ekelund, Lars Bo Andersen and The European Youth Heart Study Team
The aim of the European Youth Heart Study (EYHS) is to establish the nature, strength, and interactions between personal, environmental, and lifestyle influences on cardiovascular disease (CVD) risk factors in European children.
The EYHS is an international study measuring CVD risk factors, and their associated influences, in children. Relationships between these independent factors and risk of disease will inform the design of CVD interventions in children. A minimum of 1000 boys and girls ages 9 and 15 y were recruited from four European countries—Denmark, Estonia, Norway, and Portugal. Variables measured included physical, biochemical, lifestyle, psychosocial, and sociodemographic data.
Of the 5664 children invited to participate, 4169 (74%) accepted. Response rates for most individual tests were moderate to high. All test protocols were well received by the children.
EYHS protocols are valid, reliable, acceptable to children, and feasible for use in large, field-based studies.