Purpose To examine synergistic associations between developmental trajectories of motor competence, perceived motor competence, cardiorespiratory fitness, moderate-to-vigorous physical activity (MVPA), and body mass index (BMI) from late childhood to adolescence.

Methods In this three-year follow-up study, motor competence, perceived motor competence, cardiorespiratory fitness, MVPA, and BMI were assessed in 1 167 Finnish school-aged children (girls = 583, boys = 565; Mage = 11.27 ± 0.33). MVPA was measured using hip-mounted accelerometers. Developmental trajectories were analyzed using latent growth curve modeling.

Results The development of motor competence, cardiorespiratory fitness and BMI was positive over time, whereas the development of perceived motor competence and physical activity was negative. The development of BMI was inversely associated with the development of cardiorespiratory fitness and physical activity.

Conclusion In the transition from late childhood to adolescence, motor competence, cardiorespiratory fitness, and BMI increased, and perceived motor competence and physical activity decreased. However, individual variance in the developmental trajectories was significant. Moreover, children with a greater increase in BMI showed a greater decrease in cardiorespiratory fitness and physical activity from late childhood to adolescence.