The Influence of Vibration on Bone Mineral Density in Women Who Have Weak Bones After Menopause

BACKGROUND: Recent animal studies have shown that whole-body vibration increases bone mineral density. The effect of whole-body vibration on bone has been examined in only six small human studies with inconsistent results. Two of these studies have shown whole-body vibration reduces bone loss after menopause. Studies that used higher speed whole-body vibration may have produced greater reductions in bone loss. OBJECTIVE AND HYPOTHESIS: The objective of this study is to examine the effects of two whole-body vibration speeds trabecular BMD in the lower leg in osteopenic postmenopausal women. Two hundred postmenopausal women will take part in this 12-month study. Women will be randomly assigned into three groups (67 women per group) and these groups will be compared. Group 1 will receive very fast (90 Hz) whole-body vibration, Group 2 will receive fast (30 Hz) whole-body vibration, and Group 3 will not receive whole-body vibration. The hypothesis of this study is that the in comparison to Group 3 (no vibration), Groups 1 (very fast vibration, 90 Hz) and 2 (fast vibration, 30 Hz) will experience reduced bone loss over 12 months, and that the greatest reduction in bone loss will be experienced by Group 1. METHODOLOGY: Women with any clinical conditions that affect bone and those receiving drugs that affect bone will be excluded. The whole-body vibration therapy will involve standing barefoot and upright on a vibration platform daily for 20 minutes. Data will be collected at baseline, and at 12 months of follow-up. Our primary analysis will evaluate whether there are differences in changes in trabecular BMD in the lower leg (as measured by peripheral quantitative computed tomography; pQCT) between Groups 1, 2, and 3. Our secondary analyses will examine whether there are differences in changes in the following bone characteristics between Groups 1, 2, and 3: 1. trabecular bone quality in the lower leg (as measured by pQCT) 2. cortical bone BMD and quality in the lower leg (as measured by pQCT) 3. trabecular and cortical bone BMD and quality in the wrist (as measured by pQCT) 4. BMD at the hip and spine (as measured by dual x-ray absorptiometry, DXA) 5. BMD and quality at the heel (as measured by quantitative ultrasound). SIGNIFICANCE: Based on current scientific understanding of bone remodeling, vibration devices have the potential to play a significant part in maintaining bone health in postmenopausal women. The results of this study will help us determine whether low-magnitude, high-frequency WBV at different vibration rates produces variable effects on bone, hence explaining the inconsistency of the results obtained previously. This study will also lay the ground work for future large-scale randomized controlled trials that are needed to investigate the long-term effects of WBV on preventing postmenopausal bone loss. If effective, WBV can be another non-pharmaceutical strategy to decrease bone loss in postmenopausal women. This in turn will decrease the number of osteoporotic fractures and their associated morbidity and mortality.