Comparison of tibial geometry, density and strength between adult female dancers, gymnasts and runners

Abstract

Physical activity has a site-specific osteogenic effect that is known to positively improve bone health (Schoenau, 2006, Greene, 2006, Uusi-Rasi, 2006). The effect of dancing on bone health has received sparse attention and the extent of the osteogenic effect of dancing is not known. Given that dancing may be considered a medium impact activity, one would expect that the magnitude of its osteogenic effect might be between those of high impact activities such as gymnastics and cyclic low impact activities like running with the most pronounced effects in the weight bearing bones such as the tibia and femur. Thus, the purpose of this study is to compare the osteogenic effects of dance, gymnastics and middle/long-distance running in adult females, as measured by tibial geometry, density, and strength. Methods:</bold> Eleven dance majors and eleven collegiate gymnasts (ages 18-22) were recruited for the study. Runner (n=22) and control (n=19) data were obtained from the UM Laboratory of Musculoskeletal Health database (Smock et al., 2009 and Bruininks, 2009). The control subjects were young adult, sedentary females. Total cross-sectional area (ToA) was measured by peripheral quantitative computed tomography (pQCT) at the tibia (4% and 66% from its distal end); total volumetric bone mineral density (vBMD) and bone strength index (BSI) were measured at the 4% site. Polar strength-strain index (SSIp) was measured at the 66% site. </DISS_para> <DISS_para><bold>Results:</bold> After controlling for height and body mass, the distal and proximal cross-sectional areas of the tibia (ToA 4%, ToA 66%) and SSIp did not differ significantly between groups. However, total vBMD was significantly higher for dancers and gymnasts when compared to controls (p=0.01 and p=0.02, respectively). In addition, BSI was significantly higher for dancers, gymnasts, and runners when compared to controls (p=0.001, p<0.001, and p=0.03, respectively). Participants did not differ in age, weight or tibial length, assuring that the samples were not biased with respect to age and anthropometrics.Conclusion:The current results suggest that dance and gymnastics have the greatest osteogenic effects at the tibia in eumenorrheic adult females, followed by middle-long distance running, when compared to sedentary healthy controls.