Table 1.

Descriptive characteristics of the study population (n = 1028)

Involvement in organised physical activity in grade 7, n (%)
Organised extracurricular physical activity at school
No	482 (46.9)
Yes	546 (53.1)
Organised physical activity in community
No	181 (17.6)
Yes	847 (82.4)
Any organised physical activity
No	132 (12.8)
Yes	896 (87.2)
No. physical activity sessions/week in year 1, mean ± SD
Organised extracurricular physical activity at school
No	15.7 ± 10.4
Yes	17.9 ± 12.5
Organised extracurricular physical activity in community
No	11.8 ± 6.6
Yes	17.7 ± 12.1
Any organised extracurricular physical activity
No	12.5 ± 6.9
Yes	17.5 ± 12.0
Age at baseline, mean ± sd (years)	12.8 ± 0.6
Sex (n, % female)	531 (51.7)