The impact of school-time activity on total physical activity: the activitystat hypothesis (EarlyBird 46)

To explore the activitystat hypothesis in primary school children by asking whether more physical activity (PA) in school time is compensated for by less PA at other times.

Observational, repeated measures (four consecutive occasions over a 12-month period).

South-west England.

A total of 206 children (115 boys, aged 8-10 years) from 3 primary schools (S1, S2 and S3), which recorded large differences in PA during school time.

Total PA (TPA) and its moderate-and-vigorous component were recorded weekly by accelerometry, in school and out of school, and adjusted for local daily rainfall and daylight hours. Habitual PA was assessed by linear mixed-effects modelling on repeated measures.

S1 children recorded 64% more in-school PA, but S2 and S3 children compensated with correspondingly more out-of-school PA, so that TPA between the three schools was no different: 35.6 (34.3-36.9), 37.3 (36.0-38.6) and 36.2 (34.9-37.5) Units, respectively (P=0.38).

The PA of children seems to compensate in such a way that more activity at one time is met with less activity at another. The failure of PA programmes to reduce childhood obesity could be attributable to this compensation.