Abstract
We evaluated the effectiveness of a 15-week intervention that increased from three to five lessons of physical education (PE) a week on 7-year-old boys' and girls' physical fitness (PF), physical activity (PA) and sedentary behaviour on week and weekend days. A total of 212 first grade pupils (mean age 6.95 ± 0.43) from two urban schools in Poznań were randomly assigned to the experimental or control groups. The PF was measured with a battery of field tests, while health-related behaviours were assessed with the Healthy Children in Sound Communities questionnaire. There were some interaction effects noticed in the PF scores in the case of a 20-min run for boys (F(2,196) = 5.29, p = 0.0058) and for girls (F(2,220) = 3.31, p = 0.0382) and the sit-ups test for boys (F(2,196) = 1.93, p = 0.1478) and for girls (F(2,220) = 3.98, p = 0.0201) and for the sit and reach test in the case of girls (F(2,220) = 3.98, p = 0.0201). In terms of outdoor PA levels, there were no major differences between any of the examined groups. Differences were found between girls from the experimental and control groups in the post-test (p = 0.0107) and follow-up (p = 0.0390) during the weekdays, with no differences between the groups of boys. Despite the moderate effects of the extended PE time programme right after the intervention, there were some indications of progress in the follow-up experiments.