Effects of focal vibration on bone mineral density and motor performance of postmenopausal osteoporotic women

Aim. This randomized double blind controlled study is aimed at determining the effect of repeated vibratory stimuli focally applied to the contracted quadriceps muscles (repeated muscle vibration=rMV) on bone mineral density, leg power and balance of postmenopausal osteoporotic women. Methods. The study has been conducted on 40 voluntary postmenopausal osteoporotic women, randomised at 2 groups for rMV treatment and for control. The treatment group underwent rMV (100Hz, 300-500 gm; three applications per day, each lasting 10-minutes, for 3 consecutive days) applied to voluntary contracted quadriceps (VC=vibrated and contracted group). The control group, received a sham stimulation on contracted quadriceps (NV=non vibrated group). Bone mineral density T-score of proximal femur of the participants, was evaluated in two weeks before and 360 days after intervention; body balance and explosive leg power were measured 1 day before, 30 days and 360 days after treatment. Results. VC group T-score at one year didn't change significantly relative to baseline values (pretreatment: -2.61+/-0.11, post-treatment -2.62+/-0.13); conversely in NV subjects T-score decreased significantly from -2.64+/-0.15 SD down to -2.99+/-0.28 SD. A significant improvement of balance and explosive leg power was observed only in VC group at 30 and 360 days after the intervention. Conclusion. We conclude that rMV is a safe, short-lasting and non-invasive treatment that can significantly and persistently improve muscle performance and can effectively counteract progressive demineralisation in postmenopausal and osteoporotic women.