Trajectories of osteogenic physical activity in children and adolescents: A 3-year cohort study

We explored the latent profiles based on locomotor skills and cardiorespiratory fitness in Finnish schoolchildren and examined their associations with latent growth curves of osteogenic physical activity (PA) over three years.

Prospective cohort study.

Altogether 1147 Finnish adolescents aged 11-13 years participated in the study. Osteogenic PA in terms of osteogenic index (OI) was calculated based on acceleration peak histograms using all of the peaks with acceleration >1.3 g. Locomotor skills were assessed using the five-leap and side-to-side jumping tests and cardiorespiratory fitness (CRF) using 20-metre shuttle run test. The latent growth curve models for the locomotor skills and cardiorespiratory fitness profiles were tested to examine the longitudinal development of OI scores over time three years (from T0 to T3).

OI scores were lower amongst children in the "Low locomotor profile" compared with "Moderate" and "High locomotor" profiles. The OI scores linearly decreased from T0 to T3 in each locomotor profile and the decrease was similar in all the profiles. Moreover, OI scores were lower in the "Low CRF profile" compared with "Moderate" and "High CRF" profiles. The OI scores decreased in each profile over time, but the decrease was steepest in the "Low CRF profile", whereas "Moderate" and "High CRF profiles" had similar developmental trajectories.

Children with the highest locomotor skills and higher CRF accumulate more osteogenic PA than their least skilful and fit peers, which can have important implications on bone health in this critical period for bone growth.