2. Majority of ST group signal is in the 0-0.5 Hz range, whereas in the PT group there are high amplitudes from the 0-2.5 Hz range (Figure 2)

3. The ST group lost BMD and area significantly in the lumbar spine from baseline values (Table 4), and there were no differences in the PT group (Figure 3)

4. The ST group significantly lost BMD at the total hip and femoral neck from baseline (Table 3), however between groups there was no difference (Figure 3)Discussion: Within this two-year exercise program in osteopenic post-menopausal women, differences between strength training (ST) and power training (PT) on bone mineral density were measured. Significant variations in the loading stimuli (magnitude and rate) were seen between the PT group and the ST group (Figure 1). Previous studies10 found that the ground reaction forces were significantly related to the internal forces, and bone strain is directly proportional the applied force. A higher strain rate on the bone is associated with a larger adaptive bone growth response. Similarly, an increased loading frequency as seen in the PT group compared to the ST (Figure 2), has been suggested to be associated with higher osteogenic response11. Compared to no loss in the PT group, the ST group had significant BMD loss in the lumbar spine after the 2-year period. The ST group also saw significant BMD loss in the proximal femur in comparison to the PT group. These results are consistent with the above findings, as the power training group experienced greater strain, initiating greater osteogenesis. Conclusions: This study concludes that long-term power training with high movement velocity is the superior form of weight training in maintaining bone mineral density in osteopenic postmenopausal women. References: Glaser, D. & Kaplan, F. 1997 “Osteoporosis: Definition and Clinical Presentation” Spine, vol. 22, issue 24, p. 12-16 Sambrook, PN. Seeman E. Phillips SR. & Ebeling PR. 2002 “Preventing osteoporosis: outcomes of the Australian Fracture Prevention Summit” The Medical Journal of Australia, vol. 176, issue 8, p. 1-16 Zaidi, M. et al. 2009 “Bone loss or lost bone: rationale and recommendations for the diagnosis and treatment of early postmenopausal bone loss” Current Osteoporosis Reports, vol. 7, issue 4, p. 118-126 Ho, SC. Et al. 2008 “Change in bone mineral density and its determinants in pre- and perimenopausal Chinese women: the Hong Kong Perimenopausal Women Osteoporosis Study” Osteoporosis International, vol. 19, issue 12, p. 1785-1796 Szejnfeld, V.L. 1994 “Bone density in white Brazilian women: Rapid loss at the time around the menopause” Calcified Tissue International, vol. 56, no. 3, p. 186-191 Martyn-St James, M. & Carroll, S. 2008 “A meta-analysis of impact exercise on post-menopausal bone loss: the case for mixed loading programmes” British Journal of Sports Medicine, vol. 43, p. 898-908 Torgerson, D. & Bell-Syer, S. 2001 “Hormone replacement therapy and prevention of vertebral fractures: a meta-analysis of randomised trials” BMC Musculoskeletal Disorders, vol. 2, issue 7 Shea, B. et al. 2001 “Meta-Analysis of Calcium Supplementation for the Prevention of Postmenopausal Osteoporosis” Endocrine Reviews, vol. 23, issue 4, p. 552-559 Von Stengel, S. et al. 2007 “Differential effects of strength versus power training on bone mineral density in postmenopausal women: a 2-year longitudinal study” British Journal of Sports Medicine, vol. 41, p. 649-655 Bassey, E.J. et al. 1997 “Relations between compressive axial forces in an instrumented massive femoral implant, ground reaction forces, and integrated electromyog-raphs from vastuslateralis during various “osteogenic” exercises” Journal of Biomechanics, vol. 30 p. 213-223 Turner, C.H. et al. 1994 “Mechanotransduction in bone: do bone cells act as sensors of fluid flow?” The Federation of American Societies for Experimental Biology Journal, vol. 8, p. 875-878 Table 4: Osteodensitometric and maximum muscle strength variables at baseline for subjects Table 3: Exercise components in strength and power training groups Figure 1: Force-time curves for strength-training (A) and power-training (B) groups Figure 2: Contribution of the six 0.5 Hz frequency intervals to the total loading signal in the strength and power training groups Figure 3: Percentage changes in bone mineral density (BMD) between baseline and yr 2 at the lumbar spine L1-L4 (A), the proximal femur (B) and the forearm (C) in the strength and power training groups Table 1: Subjects anthropometric and nutritional data at baseline Table 2: Exercise Interventions for Subject Groups