The Effect of Whole Body Vibration on the Mechanical Properties of the Femur and Tibia in Ovariectomized Rats

The aim of this study was to determine the effect of whole-body vibration at a constant frequency and different amplitude in femur and tibia bones in ovariectomized rats. 23 ovariectomized rats divided into two exercise groups (n=9) and a SHAM group (n=5). Six healthy and non-surgical rats formed the control group. Rats in exercise and SHAM groups were placed on vibration platform for 8 weeks on the progressive time 2-5 minutes, 3-7 set and 1-minute inter-set rest time. Mechanical properties including stiffness, stress, and energy absorption and displacement percentage of the femoral and tibial were evaluated with three-point bending test after the period of the study. Stiffness index between training groups HA (P=0.024) and LA group (P=0.006) in femur and tibia compared with the sham group showed a significant increase. Stress index significantly increased between HA groups (P=0.000) and LA group (P=0.001) relative to the sham group in tibia. Energy absorb in just LA group (P=0.006) with the sham group showed a significant increase in tibia. Significantly increased control group compared to the sham was also observed in the indices (P=0.014, 0.000, 0.011) Our findings indicate a positive effect of whole-body vibration on the mechanical properties of the bone in both low and high amplitude conditions, but it was more effective in low-amplitude than high-amplitude condition. Also, whole-body vibration training is more effective to mechanical properties of tibia. Mechanical properties of bone in ovariectomized rats were close to control group level during whole body vibration.