Intensity of commonly-reported classroom-based physical activity opportunities in public schools

•Most physical activity in classrooms occurs at the moderate intensity level.•A higher proportion of physical activity is offered in the fall compared to spring.•Physical activity opportunities offered decrease at higher grade levels.

The purpose of this study was to examine the intensity levels of PA opportunities offered in public school classrooms. Schools (N = 101) in school districts (N = 25) reported PA opportunities offered in classrooms using an online data collection tool over a two-year period (2014-2016). Using a randomized sampling technique, 20-30% of teachers in each school were selected each week to report PA in their classroom. These responses resulted in N = 18,210 usable responses. A researcher determined the intensity of PA opportunities using the 2011 Compendium of Physical Activities as a guideline; two additional researchers confirmed the coded categories. A descriptive analysis of PA opportunities was conducted to describe the proportion of opportunities whose intensity levels were light (LPA), moderate (MPA), vigorous (VPA), sedentary (SED), and those of unknown intensity. Chi-square analyses were utilized to examine differences between proportions of intensity levels offered by semester. Kruskal-Wallace tests were utilized to examine differences in proportion of physical activity opportunity intensity offered by grade level. Most PA opportunities were MPA (58.7%), followed by VPA (17.6%) and LPA (11.5%). Few responses were SED (0.5%), and 11.6% were of indeterminate intensity. A greater proportion of more physically intense activities reported during the fall versus spring semesters (p < 0.0001). Differences in the intensity levels of PA offered by grade also differed, with a trend of decreasing intensity as grade level increased (p < 0.0001). This study provides insight into the PA actually occurring in classrooms; a previously underexplored construct of school-based PA.