Impact of physical activity, sedentary behaviour and muscle strength on bone stiffness in 2–10-year-old children-cross-sectional results from the IDEFICS study

Table 3 Multivariate linear regression investigating the association of reported PA data with SI, by age group

		Model 1			Model 2			Model 3^a			Model 4
		Adjusted for age, sex, country			Model 1 + adjusted for FFM, MDP, daylight duration			Model 2 + adjusted for either PA or SB			Model 3 + adjusted for muscle strength
		β	p value	R²	β	p value	R²	β	p value	R²	β	p value	R²
Preschool children (N = 1512)
Screen time (hours/week)		−0.07	0.22	17.4	−0.04	0.50	18.2	−0.04	0.50	18.4
Leisure time PA (hours/week)		0.07	0.048	17.5	0.07	0.05	18.4	0.07	0.047	18.4
WBE	Impact WBE	2.26	0.009	17.7	2.59	0.003	18.7	2.57	0.003	18.7
Reference: no exercise/WBE
School children (N = 2953)
Screen time (hours/week)		0.002	0.92	23.7	−0.01	0.63	25.3	−0.01	0.54	25.5	−0.01	0.85	25.8
Leisure time PA (hours/week)		0.05	0.023	23.8	0.05	0.019	25.5	0.05	0.020	25.5	0.04	0.037	25.8
WBE	Impact WBE	1.73	<.001	24.2	1.67	<.001	25.7	1.66	<.001	25.7	1.49	<.001	26.0
Reference: no exercise/WBE

PA physical activity, WBE weight-bearing exercise
^aIn Model 3, the independent variables were (in addition to Model 2) adjusted as follows: screen time: leisure time PA; leisure time PA and WBE: screen time

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