We quantified the moderate-to-vigorous physical activity (MVPA, heart rate ≥140 bpm) of urban public elementary school children on school days with and school days without physical education (PE) class by using continuous heart rate monitoring. The heart rate of 81 students (93.8% black) in grades 3 and 5 was recorded in 15-second intervals. On the basis of 575 school-day observations (mean 7.1 days/student), students accumulated 44.4 (standard deviation [SD], 34.4) minutes of MVPA on days with PE and 30.6 (SD, 29.9) MVPA minutes on days without PE (P < .001). School policies should promote daily PE to help children in under-resourced areas achieve the recommended 60 minutes per day of MVPA.

The aim of this study was to explore the relationship of aerobic fitness with the elementary school environment and student characteristics among 4th and 5th grade children attending urban public schools in St. Louis, MO, USA. This cross-sectional study was conducted during 2012–2015 and included 2381 children (mean age 10.5 y) who completed the FITNESSGRAM® 20-m Progressive Aerobic Cardiovascular Endurance Run. Healthy Fitness Zone (HFZ) was defined according to FITNESSGRAM® aerobic capacity criteria. Other student-level variables included age, race, National School Lunch Program eligibility, BMI z-score, weight status, and daily pedometer steps. School environment variables included playground features and playground safety, physical education and recess practices, and school census tract data on vacant houses and median household income. Bivariate analyses with sex stratification were used to identify student-level and school-level predictors of failure to achieve the aerobic HFZ; predictors were then included in a multivariable logistic regression model. Failure to meet the aerobic HFZ was observed among 33% of boys and 57% of girls. School environment was not predictive, but higher age and fewer daily steps were: each additional year of age was associated with 41% higher odds of failing to meet the aerobic HFZ among boys and 100% higher odds among girls. Conversely, each additional 1000 daily steps was associated with 15% (boys) and 13% (girls) lower odds of failure. Obesity posed a 60% higher risk of failure to meet HFZ among girls. These results highlight the importance of childhood physical activity opportunities, especially for girls residing in low-resource areas.