To determine whether aerobic fitness is more salient than weight status in predicting performance on standardized math and reading tests in fourth- to eighth-grade students.

A cross-sectional study of data abstracted from 11 743 students in 47 public schools. Aerobic fitness was defined by entering the healthy fitness zone of Fitnessgram's Progressive Aerobic Cardiovascular Endurance Run, which has been shown to correlate highly with maximum oxygen consumption. Mixed-effects logistic regression analyses were conducted to model the student-level effect of aerobic fitness status on passing the Nebraska State Accountability (NeSA) math and reading tests after adjusting for body mass index (BMI) percentile, free/reduced lunch status, sex, race, grade level, and school type.

After adjustment, aerobically fit students had greater odds of passing the NeSA math and reading tests compared with aerobically unfit students regardless of whether the students received free/reduced lunch; however, the effect of being aerobically fit on the standardized test scores was significantly greater for students not receiving free/reduced lunch. Weight status, as measured by BMI percentile, was not a significant predictor of passing the NeSA math or reading test after including free/reduced lunch status in the model.

Aerobic fitness was a significant predictor of academic performance; weight status was not. Although decreasing BMI for an overweight or obese child undoubtedly improves overall health, results indicated all students benefit academically from being aerobically fit regardless of weight or free/reduced lunch status. Therefore, to improve academic performance, school systems should focus on the aerobic fitness of every student.