Linear/nonlinear relations of activity and fitness with children’s academic achievement

A growing research base suggests that the benefits of physical activity (PA) and aerobic fitness for children extend beyond overall health/well-being to include academic achievement (AA). The majority of research studies on relations of PA and fitness with AA have used linear-only analytic approaches, thereby precluding the possibility that PA and fitness could have a differing effect on AA for those more/less active or fit. OBJECTIVE: This study aimed to evaluate both linear and nonlinear associations of PA and aerobic fitness with children's AA among a sample of 687 second and third grade students from 17 Midwest schools. STUDY DESIGN: Using baseline data (fall 2011) from a larger 3-yr intervention trial, multilevel regression analyses examined the linear and nonlinear associations of AA with PA and with progressive aerobic cardiovascular endurance run (PACER) laps (i.e., aerobic fitness), controlling for relevant covariates. RESULTS: Fitness, but not PA, had a significant quadratic