Seasonal variation in objectively measured physical activity, sedentary time, cardio-respiratory fitness and sleep duration among 8–11 year-old Danish children: a repeated-measures study

Table 4 Associations between average of the three seasons of moderate-to-vigorous physical activity, sedentary time, sleep duration and cardio-respiratory fitness with potential explaining variables in 8–11 year old Danish children

Variable¹	n	Moderate-to-vigorous physical activity (min/day) (n = 635)		Sedentary time (min/day) (n = 635)		Sleep duration (min/night) (n = 523)		Cardio-respiratory fitness (ml/kg/min) (n = 492)
		B (95%CI)	P	B (95%CI)	P	B (95%CI)	P	B (95%CI)	p
Age (years)	730	−2.7 (−4.5;-0.8)	0.046³	27.8 (21.5;34.1)	<0.001	−10.2 (−13.4;-7.1)	<0.001	0.8 (0.1;1.5)	0.03
Grade	730
3rd graders	359	Reference		Reference		Reference		Reference
4th graders	371	−5.4 (−8.7;-2.1)	<0.001	32.4 (24.4;40.4)	<0.001	−13.6 (−17.5;-9.6)	<0.001	−0.1 (−1.0;0.8)	0.87
Pubertal status	706
1	464	Reference		Reference		Reference		Reference
≥2	242	−7.5 (−11.0;-3.9)	<0.001	12.0 (3.0;21.0)	0.01	−7.2 (−11.6;-2.9)	0.001	−2.5 (−3.4;-1.6)	<0.001
Gender	730
Girls	354	Reference		Reference		Reference		Reference
Boys	376	19.9 (16.9;22.9)	<0.001	−0.3 (−8.7;8.1)	0.95	−5.1 (−9.2;-1.0)	0.01	8.0 (7.5;8.5)	<0.001
Parents born in Denmark²	730
0	79	Reference		Reference		Reference		Reference
1	89	2.3 (−4.8;9.4)	0.52	12.6 (−5.2;30.4)	0.16	20.8 (11.2;30.5)	<0.001	1.3 (−0.7;3.2)	0.20
2	562	−2.4 (−8.0;3.2)	0.40	13.5 (−0.4;27.4)	0.06⁴	19.2 (11.1;30.5)	<0.001	0.1 (−1.5;1.7)	0.89
Highest education of parents²	728
≤10 years	38	Reference		Reference		Reference		Reference
11 - 12 years	228	−3.1 (−11.6;5.3)	0.46	13.0 (−7.9;34.0)	0.22	24.4 (12.9;35.9)	<0.001	0.8 (−1.3;3.0)	0.45
13 - 16 years	295	−4.0 (−12.2;4.3)	0.35	22.5 (1.9;43.1)	0.03	26.0 (14.7;37.4)	<0.001	1.1 (−1.1;3.3)	0.31
≥17 years	167	−1.3 (−9.9;7.2)	0.76	24.0 (2.7;45.3)	0.03	23.0 (11.4;34.6)	<0.001	1.5 (−0.7;3.7)	0.20

¹All dependent variables are from the baseline assessments.
²P > 0.05 between non-reference groups.
³B = −2.4 (95%CI = −5.8;1.0, P = 0.17) among children with a valid cardio-respiratory fitness test (n = 413).
⁴B = 16.6 (95%CI = 3.4;29.9, P = 0.01) if wear-time was included as covariate.

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