Descriptive characteristics of the 199 study participants
| Boys (n=114) | Girls (n=85) | |
| Physical activity | ||
| GPA (cpm), mean, SD | 747.7±236.8 | 613.8±157.5 |
| MVPA (min), mean, SD | 45.5±19.8 | 34.6±13.8 |
| Biological domain | ||
| Born January to June, n (%) | 53 (47) | 48 (57) |
| Born July to December, n (%) | 61 (53) | 37 (43) |
| Age (years) baseline, mean, SD | 7.8±0.6 | 7.8±0.6 |
| Age (years) 2-year follow-up, mean, SD | 9.8±0.6 | 9.8±0.6 |
| Height (cm), mean, SD | 129.3±6.8 | 128.4±7.3 |
| Weight (kg), mean, SD | 28.1±5.9 | 27.2±5.2 |
| Body mass index (kg/m2), mean, SD | 16.7±2.4 | 16.4±2.2 |
| Social domain | ||
| Screen time activity (hours/week), mean, SD | 12.5±5.3 | 10.8±5.0 |
| Do not partake organised leisure time PA, n (%) | 24 (21) | 21 (25) |
| Partake organised leisure time PA, n (%) | 90 (79) | 64 (75) |
| No sibling member in sport association, n (%) | 47 (41) | 32 (38) |
| Sibling member in sport association, n (%) | 67 (59) | 53 (62) |
| Parental physical activity (hours/week), mean, SD | 2.7±2.0 | 2.5±2.0 |
| No parent agreed exercise was important, n (%) | 36 (32) | 34 (40) |
| One or two parents agreed exercise was important, n (%) | 78 (68) | 51 (60) |
| No parent with postsecondary degree, n (%) | 37 (32) | 17 (20) |
| One or two parents with postsecondary degree, n (%) | 77 (68) | 68 (80) |
| Environmental domain | ||
| Allocation 200 min school PA/week, n (%) | 67 (59) | 42 (49) |
| Allocation to 60 min school PA/week, n (%) | 47 (41) | 43 (51) |
GPA, general physical activity; MVPA, moderate to vigorous physical activity; PA, physical activity.