Mechanical Stimulation in the Form of Vibration Prevents Postmenopausal Bone Loss in Ovariectomized Rats

Abstract.

Physical exercise is recommended for the prevention and treatment of osteoporosis. However, its exact role and effectiveness in adulthood is unclear. While vigorous exercise of long duration enhances bone density, few adult individuals comply with such training programs. The present study evaluates the influence of nonphysiological mechanical stimulation, in the form of low intensity vibration (frequency: 50 Hz, acceleration: 2 g, 30 min/day for 5 days/week), on the prevention of bone loss in an animal model of postmenopausal osteoporosis. In the ovariectomised groups of rats a statistically significant (p < 0.05) decrease of bone density (femur and tibia) was recorded at 5 weeks postovariectomy. This effect was maintained for the 12 week duration of the study. Vibration prevented early bone loss after ovariectomy. Vibrated ovariectomised rats showed statistically significantly higher (p < 0.05) BMD values compared to those of their ovariectomised controls at 5 weeks. Vibration did not influence the bone density of the SHAM-operated rats. Although vibration increased ultimate strength (fracture load of the rat femur) in the ovariectomised rats, this finding was not statistically significant. Our data indicate that this method of safe and easily applicable vibration, in the form of a vibrating platform, is effective in preventing early postovariectomy bone loss in an animal model.