Bone Abstracts

Objectives: Maximising peak bone mass (PBM) during growth is an essential part in the prevention of fractures and osteoporosis later in life. Two of the most important modifiable factors influencing PBM are diet and physical activity (PA). These factors can have either a direct or indirect effect on bone. For example, increasing PA would increase loads directly to the bone or cause muscle changes which would drive changes in bone. This study aimed to assess whether there was a direct association between lifestyle factors (dairy consumption, PA and sedentary behaviour (SB)) and bone size and density that was not explained by body composition.

Methods: Measurements of bone (pQCT), body composition (BodPod), food consumption and PA (accelerometry) were collected in 160 children (6–12 years). A novel statistical approach based on Sequences of Regressions, a subclass of Graphical Markov models, was used to investigate the role of lifestyle factors and body composition on bone outcomes.

Results: SB had a direct, inverse association with cross-sectional area (CSA) and vBMD at the distal tibia but not with diaphyseal parameters. No direct associations were found between vigorous PA (VPA) and bone parameters. However, VPA was associated with both lean mass (LM) and fat mass, which were directly associated with bone parameters. LM had a direct beneficial impact on all bone parameters, except cortical vBMD at the diaphyseal tibia. Dairy consumption was not associated with any outcome.

Conclusion: This paediatric study indicated that SB showed a direct inverse association with CSA at the distal tibia, whereas VPA was indirectly associated with bone outcomes via its association with body composition. This investigation contributes to the understanding of the role of SB and VPA in bone development which are important to consider when translating these findings into messages promoting healthy bone growth.

Disclosure: The authors declared no competing interests.