Table 3.

Changes in social and motivational influences on breaking up classroom sitting time every 15 min (mean ± SD) and impact on the intervention group relative to the control group at T2.

	Intervention group mean (SD)a		Comparison group mean (SD)a		Group differences b
	T0	T2	T0	T2	b (95%CI)	β	p
Habit strength (score)	9.0 ± 5.7	9.8 ± 5.7	7.4 ± 4.0	6.1 ± 3.0	2.8 (0.9, 4.8)	0.3	0.004
Self-efficacy for regular breaks in sitting	7.1 ± 3.0	7.4 ± 2.7	5.5 ± 3.2	4.6 ± 3.4	2.3 (1.0, 3.5)	0.3	0.000
Influences on breaking up classroom sitting time every 15 min
Having a teacher/classmate remind me	4.2 ± 1.7	4.4 ± 1.7	3.5 ± 2.0	2.9 ± 1.8	0.9 (0.1, 1.6)	0.2	0.027
Having class activities as “standing activities”	4.4 ± 1.6	4.0 ± 1.7	3.1 ± 1.8	2.9 ± 1.8	0.1 (–0.7, 0.8)	0.0	0.509
Hard if friends/classmates were not doing it	3.7 ± 1.7	3.6 ± 1.7	3.4 ± 1.8	3.1 ± 2.0	0.2 (–0.6, 1.1)	0.1	0.625
Low priority	3.2 ± 1.6	3.3 ± 1.5	3.2 ± 1.6	2.7 ± 1.8	0.6 (–0.1, 1.3)	0.2	0.157
Don't have motivation	3.1 ± 1.8	3.1 ± 1.7	2.8 ± 1.5	2.9 ± 1.9	0.4 (–0.4, 1.2)	0.1	0.344
Too much classwork	3.1 ± 1.8	2.9 ± 1.5	2.9 ± 1.6	2.8 ± 1.9	–0.1 (–0.9, 0.6)	–0.0	0.723
Not enough energy	2.6 ± 1.8	2.8 ± 1.6	2.6 ± 1.4	2.5 ± 1.7	0.5 (–0.3, 1.2)	0.1	0.210
Wouldn't benefit my ability to complete work	3.0 ± 1.9	2.8 ± 1.4	3.2 ± 1.6	2.4 ± 1.7	0.4 (–0.3, 1.1)	0.1	0.305
Feel too self-conscious doing so	2.5 ± 1.6	2.5 ± 1.6	2.7 ± 1.7	2.6 ± 1.8	–0.1 (–0.8, 0.6)	–0.0	0.815
Don't believe it would benefit my health	2.3 ± 1.6	2.4 ± 1.3	2.8 ± 1.4	2.3 ± 1.7	0.4 (–0.3, 1.0)	0.1	0.268

Notes: T0 = baseline; T2 = 17 weeks post-baseline.

^aMeans and standard deviation (SD) come from all available data (before the last case was carried forward).

^bResults from intention to treat linear mixed models comparing intervention and comparisons groups (coefficients (b), 95%CI, p value, standardized beta weights(β)), adjusted for baseline level of outcome, age, and sex.

Abbreviation: 95%CI = 95% confidence interval.