The Effect of 8 Mos of Twice-Weekly Low- or Higher Intensity Whole Body Vibration on Risk Factors for Postmenopausal Hip Fracture

Abstract

Objective: Whole-body vibration (WBV) is a potential therapy for age-related loss of musculoskeletal competence. Vibration has improved bone in animal models but human evidence is limited. Relative efficacy of low versus high intensity WBV is also unknown. Our goal was to observe the effect of brief low (LoWBV) and higher intensity WBV (HiWBV) on risk factors for hip fracture in postmenopausal women. Design: We utilized an 8-month randomized controlled trial design to examine the influence of twice-weekly LoWBV (15mins, 30Hz, 0.3g) or HiWBV (2x3mins, 12.5Hz, 1g) on anthropometrics, bone (whole body, hip, spine, forearm, heel), muscle (wall squat, chair rise), and balance (tandem walk, single leg stance). Physical activity, daily calcium and compliance were recorded. Effects were examined by repeated measures ANCOVA, controlling for age, height, weight, calcium, physical activity, compliance, and baseline values. Results: 47 women (71.5?9.0 years) completed the trial. There were no between-group differences in any measure at 8 months, but within-group effects were evident. Controls lost bone at the trochanter (-6%, p=0.03) and lumbar spine (-6.6%, p=0.02) while WBV groups did not. WBV subjects improved wall squat (up to 120%, p=0.004) and chair rise performance (up to 10.5%, p=0.05). Conclusions: 8 months of twice-weekly WBV may reduce bone loss at the hip and spine and improve lower extremity muscle function. These changes may translate to a decreased risk of falls and hip fracture.