Long-term Effects of Mechanical Vibration Stimulus on the Bone Formation of Wistar Rats: An Assessment Method Based on X-rays Images.

Background Bone is a complex living tissue that adapts itself to the demands of mechanical stimuli such as physical activity and exercise. Whole-body vibration (WBV) is a type of exercise characterized by the transmission of mechanical vibration stimuli produced by a vibrating platform. This study aimed to investigated, in experimental model, the effect of WBV exercise on the bone in different frequencies through X-ray analysis. Materials and Methods Wistar rats were divided in three groups: control, exposed to WBV of 10 Hz and exposed to WBV of 20 Hz, during 8-weeks. All procedures to obtain the radiographic images were carried out before and after the experiments. The femur linear size and bone density measurements through radiographic images were performed in all animals. A factor of increase for bone density (FIBD) was determined. Results No differences were observed in the qualitative comparison between the groups, as well as radiographic bone density before the experiment. However, after the experiment the bone density increased in the rats exposed to WBV of 10 Hz and 20 Hz compared to control group. Also, the FIBD was higher in the groups exposed to WBV in comparison with control. Conclusion These findings indicate an increase of the bone density dependent of the vibration stimulus frequency. In addition, this increase suggests a possible osteogenic effect to the mechanical vibrations of 10 and 20 Hz.