The associations of different recess types on physical activity and sedentary behaviour in Estonian primary school students.

Students' physical activity (PA) levels tend to decrease with increasing age; however, the school day structure can potentially influence students' PA levels. This study aimed to measure and compare objective levels of PA during recess and school time between schools with different recess types. 15 different schools were selected, and accelerometry-based PA levels of 9-13-year-old students were measured. Schools were selected based on the recess types: (i) 'daily outdoor recess'; (ii) 'irregular outdoor recess'; (iii) 'indoor recess'. The 'daily outdoor recess' group reached the highest moderate-to-vigorous PA (MVPA) during recess compared to other groups. 'Indoor recess' group had more sedentary time during recess compared to 'irregular outdoor recess' and 'daily outdoor recess' groups (43.6 ± 1.0%, 34.0 ± 1.0%, 30.8 ± 0.8%, respectively; P < .05). Time in MVPA was unchanged during recess across all grades in the 'daily outdoor recess' group (from 22.8% to 25.6%), while decreased MVPA from 27% to 17% and from 21% to 10% was found in 'irregular outdoor recess' and 'indoor recess' group, respectively; P < .05. Sedentary time increased from 34% to 52% in the 'indoor recess' group and from 26% to 43% in the 'irregular outdoor recess' group (P < .05). There was a positive association between the recess length and MVPA minutes acquired during recess; however, during a 15-25 min outdoor recess, students spent more time in MVPA compared to a 30-50 min outdoor recess (28%-30.5%, 21%-23%, respectively). The findings emphasize that unstructured outdoor recess has a high potential to maintain the MVPA levels with increasing age.