Table 1.
Descriptive statistics of the study sample
| All (N = 158) | Cohort 7th Graders (N = 98) | Cohort 9th Graders (N = 60) | ||||
|---|---|---|---|---|---|---|
| Baseline | Follow-up | Baseline (Grade 7) | Follow-up (Grade 8) | Baseline (Grade 9) | Follow-up (Grade 10) | |
| Age (years) | 13.60 ± 1.13 | 14.62 ± 1.20* | 12.79 ± 0.45 | 13.75 ± 0.42* | 14.92 ± 0.47 | 16.04 ± 0.48* |
| Sex | ||||||
| Boys | 61 (38.6 %) | 38 (38.8 %) | 23 (38.3 %) | |||
| Girls | 97 | 60 | 37 | |||
| Nationality | ||||||
| Native Dutch | 140 (88.6 %) | 88 (89.8 %) | 52 (86.7 %) | |||
| Non-native Dutch | 18 | 10 | 8 | |||
| Educational level | ||||||
| SGSE | 40 (25.3 %) | 31 (31.6 %) | 9 (15.0 %) | |||
| UPE | 118 | 67 | 51 | |||
| SES | ||||||
| Low/medium | 34 (21.9 %) | 21 (21.9 %) | 13 (22.0 %) | |||
| High | 121 | 75 | 46 | |||
| Body mass index (kg/m2) | 18.75 ± 2.82 | 19.45 ± 2.83* | 17.88 ± 2.81 | 18.72 ± 2.89* | 20.18 ± 2.21 | 20.65 ± 2.30* |
| Cardiovascular fitness (VO2max) | 51.53 ± 5.51 | 51.02 ± 6.14* | 51.81 ± 5.72 | 51.70 ± 6.19 | 51.06 ± 5.17 | 49.90 ± 5.94* |
| Total PA (Accelerometer steps) | 69908 ± 18786 | 59229 ± 15021* | 73672 ± 18208B | 58405 ± 13809*B | 63759 ± 18223B | 60573 ± 16851B |
| Depressive symptoms | 11.62 ± 9.20 | 10.21 ± 8.95* | 10.99 ± 9.01 | 9.12 ± 8.03* B | 12.65 ± 9.49 | 11.98 ± 10.10 B |
| Self-esteem | 22.02 ± 5.34 | 22.65 ± 5.30 | 22.39 ± 5.27 | 23.49 ± 4.93*B | 21.42 ± 5.45 | 21.29 ± 5.62B |
SGSE senior general secondary education, UPE university preparatory education, Total PA total amount of physical activity per week measured objectively by accelerometer, VO2max maximum oxygen consumption
* significantly different from baseline at p < .05
B indicates significant difference between 7th graders and 9th graders