In French primary schools, children participate in 3 compulsory hours of physical education (PE) each week unless they have a medical contra-indication. But, there is no scientific evidence (randomized trial) that a weekly physical activity splitting up of these 3 hours of PE brings or not the same effects, particularly to prevent overweight or obesity.

Regul'aps is a cluster randomized controlled trial which wants to evaluate whether splitting up the 3 hours into 3 or 4 sessions (vs. 1-2 sessions) of PE per week has an effect on speed of a BMI increase and on health-related quality of life (HRQoL) over the school year.

Study hypothesis: reduction of speed of increase of BMI and an increase of HRQoL

Inclusion Criteria:

• All teachers under the cover of the headmasters in charge of classes from grades 2 to 5 in 2 counties in the Lorraine region of France (Meurthe-et-Moselle and Vosges [District of Golbey])
• headmasters or teachers had to agree to modify the organisation of PE sessions

Exclusion Criteria:

• Classes composed only of 2d grade
• Set schedule of physical educational sessions