Effectiveness of the Let's Move It multi-level vocational school-based intervention on physical activity and...

Low levels of physical activity (PA), more prevalent among those with low education, require effective interventions. Fewer trials have tested interventions to decrease sedentary behavior (SB). No school-based interventions have shown lasting effects on PA or SB in vocational schools.

To examine whether the Let's Move It intervention has effects on behavioral and clinical outcomes among vocational students after 2 and 14 months.

A cluster randomized trial in 6 school units in vocational education in Finland (N = 1112) (mean age 18.5 years, range 15-46). The multi-component intervention targeted in-class activity opportunities (eg, teacher-led activity breaks, equipment in classrooms), and students' motivation and self-regulation (eg, 6 group sessions, à 45-60 min, during the intensive intervention period of 2 months). Valid (≥ 4 days, ≥ 10 h/day) accelerometer data were obtained from 741 students at baseline, 521 (70.3%) at 2 months, and 406 (54.8%) at 14 months.

No evidence of a significant intervention effect on the co-primary outcomes (moderate-to-vigorous PA, SB, breaks in SB) was found. Participants in the intervention arm reduced their total daily SB time by 32 min (95% CI, -43.2 to -20.8) on weekdays, compared with the control arm's reduction of 8.6 (95% CI, -19.5 to 2.3) and engaged in more accelerometer-measured light PA during school time. Few differences were found in secondary outcomes. The fidelity of intervention delivery was relatively good.

This school-based intervention did not affect leisure-time activity. Despite a positive outcome on school-time light PA, more comprehensive or intensive environmental changes may be needed to meaningfully improve vocational students' total activity.