Bone Abstracts

The literature has suggested that bone mineral content is modulated by muscle mass and activity. We investigated the relationship between DXA assessed total body bone mineral content, total body lean mass, appendicular lean mass and obesity (a possible marker of inactivity) in a population of 73 boys between the age of 7 and 19 using a Norland XR-46 system.

Regression analysis shows that in these growing boys there is a strong positive relationship between total body bone mineral content and either total body lean mass (y=0.0503x+396.09; r=0.9718; P<0.001) or appendicular lean mass (y=395.62x – 415.69; r=0.8737; P<0.001). Analysis of covariance for total body bone mineral to total body lean mass regressions in groups with normal or low (<7.26 kg/m²) appendicular lean mass showed that regression slopes did not differ but that subjects with low appendicular lean mass also had lower bone mineral content. When analysis of covariance was carried out on total body bone mineral to total body lean mass regressions for DXA assessed obese and non-obese subjects no difference was seen in regression slopes or in values.

In conclusion, the data show that there is a strong positive relationship between total body lean mass and bone mineral content that is also reflected in calculated appendicular lean mass. The study also shows that, in this population, this relationship is not altered by zero.