The purpose of the present study was to reveal an appropriate model for predicting physical activity levels by
examining factors such as age, gender and body fatness using children participating in the European Youth Heart Study
(EYHS). In recent decades it has been reported that children have become less physically active. Moreover, there is
increasing evidence that even the youngest children are becoming fatter [1]. Additionally, very limited data that already
exists regarding children’s activity has been collected using objective measurement techniques.

Participants were 2185 children aged 9 (grade 3) and 15 (grade 9) years old from Denmark, Portugal, Estonia and
Norway. Physical activity levels were assessed using the MTI accelerometer model 7164 (Manufacturing Technology
Incorporated formally known as the Computer Science Applications activity monitor, Shalimar, FI). Skinfold
thicknesses were obtained with Harpenden fat callipers from four sites, at the biceps, triceps, subscapular, and suprailiac
[2] and summed for the estimation of body fatness. All statistical analysis performed using the Statistical Package for
the Social Sciences (SPSS) version 11. Linear regression analysis was conducted to evaluate if age, gender, and body
fatness predict physical activity levels in 9 and 15 year-old boys and girls. In order to identify gender and age specific
associations linear regression analysis was carried out four different times, for all four age and gender groups.

Linear regression analysis revealed that all independent variables such as age, gender and sum of four skinfolds
contributed significantly to the prediction of physical activity levels as long as children aged 9 years old (grade 3) are
concerned. More specifically, for girls grade 3, R for regression was significantly different from zero F (1,667)= 6,044,
p<0,05 while for boys grade 3, R for regression was significantly different from zero F (1,674)= 5,399, p<0,05 as well.
Table 1, below displays all the important findings. On the other hand, when 15 years old (grade 9) girls and boys were
tested no statistical significant differences in predicting physical activity levels were shown.

There is an inverse relationship observed between the younger children and physical activity levels. More precise, fatter
children tend to be less physically active. This observation is apparent in both younger boys and girls. Finally during the
adolescent years no association was found between physical activity levels and body fatness.

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