Development of accelerometer-based light to vigorous physical activity in fitness profiles of school-aged children.

This study examined the developmental trajectories of light (LPA) and moderate-to-vigorous physical activity (MVPA) in fitness profiles derived from motor competence, perceived motor competence, health-related fitness, and MVPA behavior. Locomotor, stability, and object control skills, muscular and cardiovascular fitness, and physical activity were assessed in 510 (girls 285 and boys 225) Finnish school-aged children (M  = 11.26 ± 33 years) over three years. Physical activity was measured using hip-mounted accelerometers. Fitness profiles were identified using latent profile analysis, and the development of physical activity levels across four assessments was analyzed with latent growth curve models. Results showed that (1) three homogeneous profiles were identified: At-risk, Intermediate, and Desirable; (2) the Desirable group was more physically active than the other groups, the Intermediate group was more physical active than the At-risk group; and (3) LPA decreased similarly over time, while MVPA remained stable in all three profiles. Initial more advanced motor competence, perceived motor competence, health-related fitness, and higher MVPA behavior were associated with higher levels of long-term LPA and MVPA. This finding supports the importance of motor competence skills acquisition in the early school years. Attention should also be paid to increasing engagement in light physical activities, especially in inactive or insufficiently active children with low motor competence skills.