Table 1.

Descriptive characteristics of participants

	Total sample (N = 6229)	Boys (N = 2838)	Girls (N = 3391)
Age (year)	10.4 (0.6)	10.5 (0.6)	10.4 (0.6)
Highest parental education (%)
Did not complete high school	19.7	19.3	20.1
Completed high school or some college	42.5	43.1	41.8
Completed bachelor’s or postgraduate degree	37.8	37.6	38.1
BMI (kg/m2)	18.4 (3.4)	18.4 (3.4)	18.4 (3.5)
Obesity (%)a	12.4	15.1	10.1
Moderate-to-vigorous physical activity (min/day)	60.3 (24.8)	69.8 (25.8)	52.3 (20.9)
Screen time (h/day)	2.9 (1.7)	3.2 (1.8)	2.6 (1.6)
Outdoor time (%)
Before school
<1 h	78.8	78.6	79.0
1 h	12.4	12.3	12.5
2 h	4.5	4.8	4.3
3 h	2.0	2.0	2.0
4 h	1.1	1.1	1.0
≥5 h	1.2	1.2	1.2
After school
<1 h	32.4	30.2	34.2
1 h	24.5	23.2	25.6
2 h	20.0	20.3	19.8
3 h	11.1	12.2	10.2
4 h	6.0	7.5	4.7
≥5 h	6.0	6.6	5.5
On weekends
<1 h	12.4	11.5	13.2
1 h	14.7	12.6	16.5
2 h	21.4	20.0	22.6
3 h	18.6	18.7	18.5
4 h	14.3	15.3	13.4
≥5 h	18.6	21.9	15.8
Outdoor time (h/day)
Before school	0.77 (0.75)	0.77 (0.75)	0.77 (0.74)
After school	1.68 (1.33)	1.79 (1.37)	1.59 (1.28)
On weekends	2.69 (1.54)	2.85 (1.56)	2.57 (1.51)
Overallb	2.52 (1.45)	2.64 (1.47)	2.42 (1.42)

BMI, body mass index.

^aObesity defined according to the World Health Organization criteria.²³

^bOverall outdoor time (h/day) was calculated as [(5 × outdoor time on weekdays) + (2 × outdoor time on weekend days)]/7.

Data are shown as mean (standard deviation) unless otherwise indicated.