Effect of High-Impact Aerobics and Strength Training on BMD in Young Women Aged 20-35 Years

To evaluate the effects of a 12-month exercise intervention using either high-impact step aerobic exercise or moderate-intensity strength training on areal bone mineral density (aBMD) we studied 51 untrained women, aged 20-35 years, for this study. Whole body and heel and wrist aBMD were measured by dual-energy X-ray absorptiometry (DXA, Hologic or PIXI Lunar). Subjects were randomly assigned to: impact-loaded step aerobic exercise (SA, n = 15), moderate-intensity lower body strength training (ST, n = 16) or non-exercise control (CON, n = 20). Data analysis only included those who completed 95% of each training routine and attended at least 80% of all sessions. Group differences in aBMD, leg press strength and urinary cross-link deoxypridinoline (mu DPD) were analysed using analysis of variance. After a 12-month intervention, the SA elicited an increase in aBMD of the heel (4.4%, p < 0.05) and leg press strength (15%, p < 0.05), relative to baseline. Meanwhile, the ST showed an increase in leg press strength (48%, p < 0.05) with no significant increase in aBMD at any measured site. Similar and unchanged mu DPD was observed in all 3 groups at baseline, 6 and 12 months. In conclusion, a 12-month high-impact step aerobic exercise resulted in a significant increase in the heel aBMD in untrained young women, who complied with the exercise regimen. A moderate intensity strength training intervention of similar duration had no effect on aBMD although leg strength increased significantly.