Novel, high-frequency, low-strain mechanical loading for premenopausal women with low bone mass: early findings

Universally safe and effective methods of mechanically loading the skeleton to improve strength and prevent fracture have yet to be identified. To be osteogenic, mechanical strains must either be of substantial magnitude or applied at high frequency (>15 Hz). High-magnitude loads place frail bones at risk of fracture. Active loading can rarely be achieved at a frequency faster than 2-3 Hz. A 12-month, uncontrolled, prospective, pilot intervention trial was conducted with five premenopausal Caucasian women with low bone mass. Subjects stood on a vibrating platform (Optimass model 1000 Mechanical Strain Device) and received a 0.2-g stimulus at 30 Hz, 2 x 10 min/day, for 12 months. Bone mineral density (BMD) was measured at the whole body, lumbar spine, proximal femora (PF), and distal radius at baseline and 6 and 12 months by DXA (Hologic QDR-1000/W). Blood and urine were collected at baseline and 3, 6, 9 and 12 months for markers of bone resorption and formation. A mean percent BMD increase of 2.03% +/- 0.33% (P < 0.02) was detected at the non-dominant PF after 12 months. Trends for increases were observed at all other sites with the exception of the dominant PF. No uniform trends were observed in bone resorption and formation markers. One subject, on Fosamax, increased BMD by 6% at the lumbar spine and 4.4% at the distal radius. Preliminary findings provide evidence of a possible positive response of regions of low bone mass to brief daily bouts of in-home, passive, noninvasive, low-strain, high-frequency, mechanical loading.