Cross-sectional and longitudinal associations of screen time and physical activity with school performance at different types of secondary school

Table 3 Longitudinal analysis: Prediction of school grades at follow-up by the consumption of different screen-based media and different forms of physical activity at baseline

	Outcomes at follow-up: school grades in
Predictors at baseline	Mathematics		German		Physical Education
Predictors at baseline	b	CI (95%)	b	CI (95%)	b	CI (95%)
TV/video	-0.01	-0.06 - 0.05	-0.02	-0.07 - 0.03	0.07**	0.02 - 0.13
Game console	0.04	-0.02 - 0.11	0.02	-0.04 - 0.08	0.01	-0.06 - 0.07
PC/internet	0.07*	0.01 - 0.12	0.04	-0.01 - 0.09	0.02	-0.03 - 0.07
Mobile phone	0.01	-0.03 - 0.06	0.01	-0.04 - 0.04	-0.02	-0.06 - 0.02
PA organized	-0.01	-0.04 - 0.03	-0.02	-0.05 - 0.01	-0.03	-0.06 - 0.01
PA non-organized	0.03	-0.01 - 0.05	-0.01	-0.03 - 0.02	-0.07***	-0.11 - -0.04^a

Better school achievement is reflected by lower school grades (following the German grading system). All associations are adjusted for gender, age, SES, year of data assessment, BMI, type of school, the other predictors, and grades at baseline.
b = regression coefficient, non-standardized, PA physical activity
^ain girls only, as revealed by a significant interaction between non-organized PA and grades in Physical Education
* p < 0.05, ** p < 0.01, *** p < .001.

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