Relationships between areal bone mineral density and jumping height in pubertal girls with different physical activity patterns.

Aim: The aim of this study was to investigate the relationship between jumping height and bone mineral density (BMD) at femoral neck and lumbar spine in pubertal girls with different physical activity pattern.

Methods: The participants were 202 adolescent girls aged 13-15 years comprising six groups: controls (N.=43); sport games (N.=56); track sprint (N.=25); rhythmic gymnastics (N.=29); swimming (N.=32); and cross-country skiing (N.=17). Body height, sitting height, and body mass were measured. Predicted age at peak height velocity (APHV), biological maturity age (years from APHV), and pubertal status by Tanner (1962) of the participants was estimated. Femoral neck and lumbar spine (L2-L4) BMD was measured by DXA. The height of vertical jumps, i.e., countermovement jump (CMJ), and rebound jumps for 15 (RJ15s) and 30 (RJ30s) seconds was obtained.

Results: RJ15s and RJ30s tests characterized best BMD at lumbar spine and femoral neck in high-impact (i.e., gymnasts and sport games) groups. Vertical jump tests had no significant correlation with measured areal BMD values in physically inactive controls, low-impact (i.e., swimmers and cross-country skiers) and moderate-impact (i.e., sprinters) groups.

Conclusions: BMD at femoral neck appears to be more sensitive to the mechanical loading compared to the BMD at lumbar spine. Repeated jumps tests (RJ15s and RJ30s) characterize bone development better than single maximal jump (CMJ) test in pubertal girls.