Background: The transition from kindergarten to first year at school is associated with a variety of psychosocial changes in children. The aim of this longitudinal study was to identify the changes in children's physical activity (PA) upon entry to first year at school; and to identify the days of the school week that exhibit low PA.
Methods: We monitored the PA levels of 176 children twice: initially in kindergarten and again in first-year classes at school. The age (mean +/- standard deviation) of children at kindergarten was 5.7 +/- 0.5 years and 6.7 +/- 0.5 years at the first year of elementary school. We evaluated PA employing the activity energy expenditure (AEE - kcal/kg/day) from Caltrac accelerometer and daily amount of steps (STEPS) from Yamax pedometer. Participants were monitored over 7 days to include a weekend.
Results: The mean AEE was 11.5 in pre-school girls and 12.9 kcal/kg/day in boys; and STEPS were 9923 steps/day in girls and 11 864 in boys on weekdays. At weekends, it was 11.5 kcal/kg/day in girls and 12.7 kcal/kg/day in boys and 10 606 steps/day in girls and 11 182 steps/day in boys. The mean AEE and STEPS in first-grade girls and boys was 9.9 and 9.8 kcal/kg/day respectively, and 7911 and 8252 steps/day respectively on weekdays, and 8.8 and 9.0 kcal/kg/day and 6872 and 7194 steps/day respectively at weekends. First-grade school children had significantly lower PA than pre-school children on weekdays (P < 0.0001) and at weekends (P < 0.0001). Decline in PA on weekdays was during time spent at school (P < 0.0001) and not during after-school children's leisure time.
Conclusion: The parts of the week when first-grade school children show low PA are the times spent in lessons and in after-school nursery and at weekends. PA needs to be promoted using intervention programmes mainly during the after-school nursery programmes and at weekends.