Table 1 Characteristics of preschool (2- < 6 years) and school (6–10 years) children, stratified by sex
Preschool children (2- < 6 years) | Primary school children (6–10 years) | |||||
|---|---|---|---|---|---|---|
Boys | Girls | All | Boys | Girls | All | |
Mean ± SD | Mean ± SD | Mean ± SD | Mean ± SD | Mean ± SD | Mean ± SD | |
Number | 804 | 708 | 1512 | 1409 | 1544 | 2953 |
Age (years) | 4.4 ± 0.9 | 4.5 ± 0.9 | 4.4 ± 0.9 | 8.1 ± 1.2 | 8.1 ± 1.2 | 8.1 ± 1.2 |
Anthropometric measures | ||||||
Bone stiffness index | 79.3 ± 14.6 | 79.8 ± 15.5 | 79.5 ± 15.0 | 82.1 ± 12.5 | 80.5 ± 11.7 | 81.3 ± 12.1 |
Body height (cm) | 116.0 ± 9.8 | 114.7 ± 9.4 | 115.4 ± 9.7 | 135.2 ± 9.0 | 134.7 ± 9.1 | 135.0 ± 9.0 |
Body weight (kg) | 21.8 ± 5.4 | 21.1 ± 4.9 | 21.5 ± 5.2 | 32.5 ± 8.7 | 32.1 ± 8.3 | 32.3 ± 8.5 |
Fat-free mass (kg) | 15.7 ± 3.6 | 13.9 ± 3.3 | 14.9 ± 3.6 | 23.1 ± 4.1 | 21.3 ± 4.0 | 22.2 ± 4.1 |
Objectively measured PA and sedentary behaviours | ||||||
Sedentary time (hours/day) | 4.4 ± 1.5 | 4.5 ± 1.4 | 4.4 ± 1.5 | 5.6 ± 1.5 | 5.7 ± 1.5 | 5.7 ± 1.5 |
Light PA (hours/day) | 6.4 ± 1.0 | 6.4 ± 1.0 | 6.4 ± 1.0 | 5.8 ± 1.1 | 5.8 ± 1.1 | 5.8 ± 1.1 |
Moderate PA (min/day) | 38 ± 18 | 29 ± 14 | 34 ± 17 | 39 ± 19 | 29 ± 14 | 34 ± 17 |
Vigorous PA (min/day) | 7 ± 7 | 6 ± 5 | 6 ± 6 | 9 ± 8 | 7 ± 6 | 8 ± 7 |
Moderate-to-vigorous PA (min/day) | 45 ± 23 | 35 ± 18 | 40 ± 21 | 48 ± 25 | 36 ± 18 | 42 ± 23 |
PA levels (cpm) | 653 ± 171 | 586 ± 147 | 622 ± 164 | 579 ± 169 | 507 ± 139 | 541 ± 158 |
Wearing time (average hours/day) | 11.6 ± 1.7 | 11.4 ± 1.7 | 11.5 ± 1.7 | 12.2 ± 1.7 | 12.1 ± 1.7 | 12.2 ± 1.7 |
Measures of muscle strength | ||||||
Jumping distance (cm) | 121 ± 25 | 114 ± 25 | 117 ± 25 | |||
Handgrip strength (kg) | 14.4 ± 3.9 | 13.2 ± 3.5 | 13.8 ± 3.7 | |||
Potential confounding lifestyle factors | ||||||
Dairy products (frequency/week) | 22 ± 12 | 21 ± 11 | 21 ± 12 | 20 ± 12 | 19 ± 12 | 20 ± 12 |
Daylight duration (hours/week) | 11.0 ± 2.8 | 10.8 ± 2.6 | 10.9 ± 2.7 | 10.8 ± 2.6 | 10.7 ± 2.6 | 10.7 ± 2.6 |
Reported PA and sedentary behaviours | ||||||
Continuous variables | ||||||
Leisure time PA (hours/week) | 17.8 ± 10.0 | 17.6 ± 9.8 | 17.7 ± 9.9 | 18.9 ± 9.8 | 17.2 ± 9.7 | 18.0 ± 9.8 |
Screen time (hours/week) | 12.2 ± 7.0 | 10.6 ± 6.3 | 11.4 ± 6.7 | 15.2 ± 8.1 | 13.3 ± 7.2 | 14.2 ± 7.7 |
Categorical variable | N (%) | N (%) | N (%) | N (%) | N (%) | N (%) |
High-to-moderate WBE | 182 (22.6) | 222 (31.4) | 404 (26.7) | 822 (58.3) | 817 (52.9) | 1639 (55.5) |
No-impact WBE / no exercise | 622 (77.4) | 486 (68.6) | 1108 (73.3) | 587 (41.7) | 727 (47.1) | 1314 (44.5) |