Bone remodeling can be stimulated by mechanical forces present in normal physical activities. In the present research, we investigated the mechanical behavior of the proximal femur of rats previously maintained in tail suspension and later, submitted to physical exercise on a treadmill. Sixty-six Wistar rats were used. Firstly, the animals were raised until the age of ninety days and then divided into five groups (two control groups and three experimental groups). The animals allocated to Control I group were killed at 118 days of age. In the S group, the animals were suspended by tail for 28 days. In Control II group, the animals were killed at 139 days of age. In group S-L (suspended and released) the rats were kept free for 21 days after tail suspension. In group S-T (suspended and trained), after tail suspension period, the rats were trained in a treadmill for 21 days. For analysis of the mechanical behavior of the bone, force was applied on the femoral head until failure. The fracture was evaluated by x-ray. Suspension caused a decrease of the maximum load and, treadmill training and post-suspension release caused the recovery of mechanical properties. But, the fracture line pattern did not show any difference among the experimental groups.
Weightlessness Simulation; Physical Conditioning; Animal; Biomechanics; Femur; Rats
