Influence of physical activity on ultrasound and dual-energy X-ray absorptiometry bone measurements in peripubertal girls: A cross-sectional study

The aim of this cross-sectional study was to investigate whether two types of physical exercise affect the growing skeleton differently. We used calca neal quantitative ultrasound measurements (QUS) and dual-energy X-ray absor ptiometry (DXA) for measurement of bone mineral density (BMD), and to test how QUS values reflect the axial DXA values in these various study groups. A total of 184 peripubertal Caucasian girls aged 11-17 years (65 gymnasts, 63 runners, and 56 nonathletic controls) were studied. Weight, height, stag e of puberty, years of training, and the amount of leisure-time physical ac tivity were recorded. Broadband ultrasound attenuation (BUA) and sound of s peed (SOS) through the calcaneus were measured. The BMD of the femoral neck and the lumbar spine were measured by DXA. The differences in mean values of bone measurements among each exercise group were more evident in puberta l than prepubertal girls. The mean BUA and SOS values of the pubertal gymna sts were 13.7% (77.8 dB/MHz versus 68.4 dB/MHz, P < 0.05) and 2.7% (1607.7 m/s versus 1572.4 m/s, P < 0.001) higher than of the controls, respectively . The mean BMD of the femoral neck in the pubertal gymnasts and runners was 20%; (0.989 g/cm(2) versus 0.824 g/cm2, P < 0.001) and 9.0% (0.901 g/cm(2) versus 0.824 g/cm(2), P < 0.05) higher than in the controls, respectively. The amount of physical activity correlated weakly but statistically signif icantly with all measured BMD and ultrasonographic values in the pubertal g roup (r = 0.19-0.35). The correlation between ultrasonographic parameters a nd BMD were weak, but significant among pubertal runners (r = 0.37-0.55) an d controls (r = 0.39-0.42), whereas the DXA values of the femoral neck and the ultrasonographic parameters of the calcaneus did not correlate among hi ghly physically active gymnasts. By stepwise regression analysis, physical activity accounted for much more of the variation in the DXA values than th e ultrasonographic values. We conclude that the beneficial influence of exe rcise on bone status as measured by ultrasound and DXA was evident in these peripubertal girls. In highly active gymnasts the increase of the calcanea l ultrasonographic values did not reflect statistically significantly the B MD values of the femoral neck.