Table 1.
Descriptive characteristics of the study sample by sex (mean ± SD unless otherwise specified).
| All | Girls | Boys | Sig. | |
|---|---|---|---|---|
| n (%) | n (%) | n (%) | p | |
| Demographics | 1139 (100) | 580 (51.0) | 558 (49.0) | |
| Age (year) | 13.4 ± 0.3 | 13.4 ± 0.3 | 13.4 ± 0.4 | 0.147 |
| Parental education, ≥12 years n (%) | 695 (71.6) | 353 (71.0) | 341 (72.2) | 0.674 |
| Participant country of birth, Sweden n (%) | 967 (85.7) | 490 (84.9) | 476 (86.4) | 0.758 |
| Height | n = 1137 | n = 580 | n = 557 | |
| Height (cm) | 161.7 | 161.1 | 162.3 | 0.007 |
| Weight | n = 1134 | n = 580 | n = 554 | |
| Weight (kg) | 52.8 | 53.1 | 52.6 | 0.491 |
| BMI | n = 1134 | n = 580 | n = 554 | |
| BMI | 20.10 ± 3.6 | 20.40 ± 3.5 | 19.80 ± 3.6 | 0.005 |
| BMI sds | 0.36 ± 1.23 | 0.45 ± 1.11 | 0.26 ± 1.35 | 0.012 |
| BMI Categories | 0.203 | |||
| Underweight n (%) | 89 (7.8) | 38 (6.6) | 51 (9.2) | |
| Normal weight n (%) | 815 (71.8) | 430 (74.1) | 384 (69.3) | |
| Overweight n (%) | 179 (15.8) | 89 (15.3) | 90 (16.2) | |
| Obese n (%) | 52 (4.6) | 23 (4.0) | 29 (5.2) | |
| Body composition | n = 1131 | n = 580 | n = 551 | <0.001 |
| Body fat (%) | 22.6 | 25.7 | 19.3 | |
| Physical activity | n = 903 | n = 490 | n = 413 | |
| SED (min/day) | 602.0 ± 66.6 | 608.9 ± 62.65 | 593.7 ± 70.2 | <0.001 |
| MVPA (min/day) | 52.0 ± 19.0 | 49.5 ± 17.7 | 54.9 ± 20.1 | <0.001 |
| Light (min/day) | 138.6 ± 30.2 | 137.5 ± 27.1 | 139.9 ± 33.6 | 0.231 |
| Accelerometer wear time (min/day) | 792.6 ± 60.8 | 796.0 ± 58.1 | 788.5 ± 63.8 | 0.067 |
| Total valid days included for accelerometer | 6.0 ± 1.1 | 6.2 ± 1.0 | 5.8 ± 1.1 | <0.001 |
| Reached the PA recommendations N (%) | 273 (30.2) | 121 (24.7) | 152 (36.8) | <0.001 |
| Organised sports | ||||
| Participated in organised sports N (%) | 787 (72.0) | 396 (71.4) | 391 (72.7) | 0.626 |
| Participation rate (per week) | 0.064 | |||
| 1–2 times N (%) | 217 (28.0) | 121 (30.9) | 96 (25.0) | |
| 3–4 times N (%) | 356 (45.9) | 181 (46.2) | 175 (45.6) | |
| ≥5 times or more N (%) | 203 (26.2) | 90(23.0) | 113 (29.4) | |
| Screen time weekdays | n = 1125 | n = 575 | n = 550 | 0.842 |
| ≤2 h N (%) | 359 (31.9) | 179 (31.1) | 180 (32.7) | |
| 3–4 h N (%) | 515 (46.0) | 267 (46.4) | 248 (45.1) | |
| ≥5 h N (%) | 251 (22.3) | 129 (22.4) | 122 (22.2) | |
| Screen time weekend | n = 1122 | n = 576 | n = 546 | <0.001 |
| ≤2 h N (%) | 178 (15.9) | 70 (12.2) | 108 (19.8) | |
| 3–4 h N (%) | 411 (36.6) | 238 (41.3) | 173 (31.7) | |
| ≥5 h N (%) | 533 (47.5) | 268 (46.5) | 265 (48.5) | |
| Fitness | n = 1020 | n = 569 | n = 451 | |
| Estimated Vo2max (mL/kg/min) | 49.5 ± 10.1 | 44.8 ± 8.5 | 55.5 ± 8.9 | <0.001 |
| Estimated Vo2max (L/min) | 2.6 ± 0.02 | 2.3 ± 0.01 | 2.9 ± 0.03 | <0.001 |
| Puberty | n = 1041 | n = 537 | n = 504 | 0.346 |
| Tanner score | 3.26 ± 0.85 | 3.28 ± 0.79 | 3.23 ± 0.91 |
BMI status according to IOTF 2012, BMI sds Karlberg et al., 2001. MVPA moderate-to-vigorous physical activity, PA physical activity. p are in bold to indicate significance (p < 0.05).