Volumetric bone mineral density is an important tool when interpreting bone mineralization in healthy children

In adults, it is well known that gender influences bone mass, but studies in children have shown contradictory results. Also, conflicting results have been reported regarding bone mineral density in obese children. Objective: To investigate bone parameters in healthy 8-year-old children and relate them to anthropometry and self-reported physical activity (PA). Design: Bone measurements were performed with dual X-ray absorptiometry in 96 children, and questionnaires were used to assess self-reported PA. Results: Bone mineral content and density differed by gender. Eighteen percent of the children were overweight/obese and they had higher bone mineral content and density than children with normal weight. Bone mineral apparent density (g/cm(3)) of the lumbar spine did not differ, since the vertebral size differed, as was also the case between genders. Self-reported weight-bearing PA influenced bone mass in the hip. Conclusion: PA influenced bone mineralization at this age. The differences in bone mineral content and density in healthy children would mainly be explained by the differences in bone size, reflected in body height and the width of the vertebrae. This indicates the importance of determining volumetric bone mineralization in children.