Table 1

Physical activity measurements and characteristics (Mean (SD) of study participants included in the analysis at the four time points)

Boys Girls
Age 7
(n=217)
Age 9
(n=209)
Age 12
(n=176)
Age 15
(n=131)
Age 7
(n=214)
Age 9
(n=219)
Age 12
(n=209)
Age 15
(n=147)
Age (years)7.5 (0.5)9.3 (0.4)12.5 (0.3)15.2 (0.4)7.5 (0.4)9.3 (0.4)12.5 (0.3)15.2 (0.4)
Anthropometry
Height (cm)125.5 (5.7)135.9 (6.3)154.2 (8.7)171.6 (8.1)124.7 (5.8)135.4 (6.3)155.2 (7.3)163.0 (6.2)
Weight (kg)26.5 (5.5)33.0 (7.2)48.3 (11.863.4 (14.5)26.7 (5.9)33.8 (7.7)51.0 (12.4)61.8 (14.4)
BMI (kg/m2)16.7 (2.4)17.7 (2.8)20.1 (3.7)21.4 (4.0)17.1 (2.6)18.3 (3.0)21.0 (4.0)23.2 (4.6)
BMI z-score0.4 (1.2)0.5 (1.2)0.7 (1.2)†‡0.5 (1.3)§0.4 (1.1)0.6 (1.1)0.7 (1.1)†‡0.8 (1.1)†‡
Fat mass (kg)6.5 (3.2)8.7 (5.0)12.0 (8.4)14.2 (10.6)6.3 (3.6)9.2 (5.0)14.2 (8.621.8 (11.5)
Accelerometer data
Wear time (min/day)672 (74.5)673 (77.6)712 (87.6725 (88.4)667 (70.9)671 (75.6)718 (82.8)720 (87.2)
Days worn6.4 (1.0)5.9 (1.3)5.8 (1.45.3 (1.6)6.2 (1.2)5.9 (1.3)5.7 (1.5)5.4 (1.7)
Total physical activity (cpm)780 (223)‡§*715 (192))§*558 (189)*482 (154)746 (222)‡§653 (193)§*469 (191)§*400 (156)
MVPA (min/day)75.5 (25.5)‡§*70.0 (23.9)§*60.3 (24.4)*51.4 (22.4)63.4 (20.9‡§*56.4 (19.8)§*47.4 (20.9)*41.0 (16.8)
  • BMI, body mass index; cpm, accelerometer counts per min, a measure of the total amount of physical activity (light intensity physical activity and MVPA combined); MVPA, moderate-to-vigorous intensity physical activity, adjusted for season (winter vs summer) at age 15 years

  • †, significantly higher than age 7 years; ‡, significantly higher than age 9 years; §, significantly higher than age 12 years; ¶, Estimated marginal means derived from linear mixed model analysis; *, significantly higher than age 15 years.