Movement Behaviours Relationship With Bone Mass And Strength In Adolescents From ALSPAC Study Using Compositional Analysis

PURPOSE: The overall purpose of this cross-sectional study was to investigate the combined association of time spent in physical activity and sedentary behaviours on bone mass and strength using a compositional analysis framework. METHODS: This study conducted using the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort. In total 2335 participants (56% females) who attended the clinical assessments at 15 years of age were included in the study. Waking-hour movement behaviours, sedentary time (ST), light physical activity (LPA), moderate physical activity (MPA) and vigorous physical activity (VPA) were assessed using accelerometers for seven consecutive days using 60s epoch. Bone mass and strength measured using dual-energy x-ray absorptiometry and peripheral quantitative computed tomography. A compositional analysis framework was used to analyse associations between time spent in different movement behaviours and bone outcomes. RESULTS: The highest co-dependence was found between ST and LPA (the log-ratio variance = 0.13). After adjusting for sex, pubertal stage and lean mass, the time spent in VPA relative to time in other movement behaviours was positively associated with whole body less head bone mineral content (BMC) (P < 0.001), leg BMC (P < 0.001), spine BMC (P = 0.02) and the area moment of inertia of the tibia (P = 0.04), but not associated with upper limb bone mass. CONCLUSIONS: The findings from this ALSPAC cohort using the compositional analysis approach indicate that only the time spent in VPA was postively related with bone mass and strength in adolescents. China Scholarship Council and University of Exeter PhD Scholarship