BONE MASS, MUSCLE STRENGTH, AND DIFFERENT BODY CONSTITUTIONAL PARAMETERS IN ADOLESCENT BOYS WITH A LOW OR MODERATE EXERCISE LEVEL

This study was conducted to evaluate the association between muscle st rength of the thigh, different body constitutional parameters, and bon e mineral density (BMD) in adolescents. The subjects were 26 healthy a dolescent boys, age 15.9 +/- 0.3 measured in total body, head, humerus , spine, femur, and tibia/fibula. Univariate correlations were measure d between the explanatory parameters height, weight, body mass index ( BMI), fat mass, lean body mass, quadriceps strength, hamstrings streng th, and each BMD site using Pearson's coefficient of correlation. The explanatory variables were also used in a multivariate analysis to exp lain each BMD site. There was a high degree of concordance when compar ing the two methods of analysis, Using the multivariate analysis, quad riceps strength and lean body mass showed significant independent corr elations to all BMD sites measured, the correlations being stronger fo r the adjacent femur and tibia/fibula than for the distant humerus and head, Hamstrings strength correlated significantly and independently with tibia/fibula BMD and spine BMD. Fat mass, BMI, and weight correla ted significantly and independently to all BMD sites except femur. Thi s study demonstrates a general relationship between BMD and different body constitutional parameters and muscle strength of the thigh. We su ggest that this association is due to equivalent increase in bone mass and other body constitutional parameters and muscle strength during n ormal puberty. This suggestion was supported by the fact that pubertal stage was significantly correlated to all body constitutional paramet ers, muscle strength of the thigh, and all BMD sites except femur. The study also provides support for a site-specific relationship between BMD and muscle strength in adolescent boys with a low or normal activi ty level.