Table 3 Adolescents characteristic with no accelerometer data compared to adolescents with valid accelerometer data, n = 1337 (Initial N = 1296)

Sex, % (n = 1337)

(n = 205)

(n = 1132)

0.011

Girls

40.5

50.1

Boys

59.5

49.9

Age, mean year (n = 1337)

12.7 (n = 205)

12.6 (n = 1132)

0.003

Age groups

(n = 205)

(n = 1132)

0.030

11-12 years

65.4

72.8

13-14 years

34.6

27.2

BMI, mean kg/m2 (n = 1266)

19.3 (n = 180)

18.8 (n = 1086)

0.016

Weight status (BMI thresholds)*** (n = 1266):

(n = 180)

(n = 1086)

0.200

Under-/normal weight

82.7

86.3

Overweight/obese

17.3

13.7

Self-reported PA in leisure time, % (n = 1313):

(n = 194)

(n = 1119)

0.042

- Performs sports several times a week (vigorous activity)

47.4

45.1

- Doing sport approx. once a week, and besides that physical active every day, cycling, walking, playing (moderate activity)

19.6

28.4

- Enjoy being physical active, but do not attend any sport clubs. Cycle, walk and are physical active when playing (light activity)

24.7

21.0

- Prefer to watch TV, play video games, listening to music or other sedentary behaviour (sedentary)

8.3

5.5

Self-reported sedentary leisure time, %: 4 h + of daily sedentary time (TV, computer, reading) in weekdays and weekend days (n = 1313)

66.0 (n = 194)

62.3 (n = 1119)

0.326