Abstract
BACKGROUND: Currently, school days are predominantly sedentary, which has negative implications for students’ physical and mental health. This study had two primary objectives: (i) to evaluate the effects of a physically active learning (PAL) intervention on physical activity (PA) levels during school hours; and (ii) to compare PA patterns during school hours and throughout the day between days with and without PAL sessions. As a secondary objective, the study analysed the intensity distribution of PA during PAL lessons. DESING AND METHODS: This randomised controlled trial included 113 students (7th -8th grade) from four secondary schools. The experimental group (n = 60) received a weekly PAL lesson for 16-weeks, while the control group (n = 53) continued with traditional teaching. PA and sedentary time were assessed by accelerometers over seven full-days before and during the last week of the intervention. Generalised linear mixed models were used to analyse the intervention’s effect on school PA and the differences in full-day and school-time PA on PAL vs. non-PAL day. Additionally, a descriptive analysis was performed to present the average distribution of PA intensities during PAL lessons. RESULTS: Although a slight reduction in sedentary time and an increase in moderate-vigorous PA (MVPA) were observed, no significant differences were found in PA levels during the overall school-time after the intervention, nor in full-day PA the day it was implemented. However, there was a significant effect on the day of implementation of a PAL lesson in MVPA levels (p < 0.001, η2 = 0.444) during school-time. CONCLUSIONS: PAL lessons can significantly increase MVPA during the school day, but these effects do not appear to persist throughout the full-day or in weekly school averages. TRIAL REGISTRATION: Clinical Trials Registry: NCT05891054. Retrospectively registered. https://clinicaltrials.gov/study/NCT05891054?cond=ACTIVE%20CLASS%20study&rank=1. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12889-026-26814-6.