Objectively measured physical activity during primary school physical education predicts intrinsic motivation independently of academic achievement level

Background: Children's participation in physical education (PE) is seen as important for developing an active lifestyle and has been positively linked to academic achievement. Physical activity (PA) levels during PE are thought to be linked to PE-motivation, although this relation is poorly understood. Aims: This study examined (1) whether children's PA-levels during PE were predictive of their PE-motivation and (2) whether the relation between PA-levels and motivation was moderated by children's academic achievement. Where previous studies focused on moderate-to-vigorous physical activity (MVPA), disregarding the potential beneficial role of lower intensities of PA, we included MVPA, light-intensity physical activity (LPA) and sedentary behaviour (SED). Sample: In total, 891 primary school students participated (mean age = 9.2 years). Methods: During one regular PE-lesson, PA-levels (using accelerometers) and PE-motivation (Intrinsic Motivation Inventory) were measured. Academic achievement in reading, mathematics and spelling was measured with standardized tests. Results: A structural equation model revealed that LPA, MVPA and academic achievement positively predicted PE-motivation. The interaction between academic achievement and PA-levels was not related to PE-motivation. SED was excluded from the models due to multicollinearity. Conclusion: Children who are more engaged in LPA and MVPA and who perform better academically generally seem to be more motivated for PE, suggesting that PA-intensity levels and PE-motivation are bidirectionally linked. Results underline the importance of also examining LPA.