Effect of 12 Months of Whole-Body Vibration Therapy on Bone Density and Structure in Postmenopausal Women
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BACKGROUND: Although data from studies in animals demonstrated beneficial effects of whole-body vibration (WBV) therapy on bone, clinical trials in postmenopausal women showed conflicting results. OBJECTIVE: To determine whether WBV improves bone density and structure. DESIGN: A 12-month, single-center, superiority, randomized, controlled trial with 3 parallel groups. (ClinicalTrials.gov registration number: NCT00420940) SETTING: Toronto General Hospital, Ontario, Canada. PARTICIPANTS: 202 healthy postmenopausal women with bone mineral density (BMD) T-scores between -1.0 and -2.5 who were not receiving prescription bone medications. INTERVENTION: Participants were randomly assigned to 1 of 3 groups (1:1:1 ratio) by using a block-randomization scheme and sealed envelopes. They were asked to stand on a low-magnitude (0.3g) 90-Hz or 30-Hz WBV platform for 20 minutes daily or to serve as control participants; all participants received calcium and vitamin D. MEASUREMENTS: Bone outcome assessors, who were blinded to group assignment, determined trabecular volumetric BMD and other measurements of the distal tibia and distal radius with high-resolution peripheral quantitative computed tomography and areal BMD with dual-energy x-ray absorptiometry at baseline and at 12 months. RESULTS: 12 months of WBV therapy had no significant effect on any bone outcomes compared with no WBV therapy. For the primary outcome of tibial trabecular volumetric BMD, mean change from baseline was 0.4 mg/cm(3) (95% CI, -0.4 to 1.2 mg/cm(3)) in the 90-Hz WBV group, -0.1 mg/cm(3) (CI, -1.0 to 0.8 mg/cm(3)) in the 30-Hz WBV group, and -0.2 mg/cm(3) (CI, -1.1 to 0.6 mg/cm(3)) in the control group (P = 0.55). Changes in areal BMD at the femoral neck, total hip, and lumbar spine were also similar among the groups. Overall, low-magnitude WBV at both 90 and 30 Hz was well-tolerated. LIMITATIONS: Adherence to WBV ranged from 65% to 79%. Double-blinding was not possible. CONCLUSION: Whole-body vibration therapy at 0.3g and 90 or 30 Hz for 12 months did not alter BMD or bone structure in postmenopausal women who received calcium and vitamin D supplementation.
