The Effect of Eight Weeks of Moderate and High Intensity Endurance Training On Biomechanical Properties of Femur in Old Male Wistar Rats

Physical activity reduces the risk of bone fractures by decelerating the bone loss and enhancing muscle strength. Such activities promote the bone strength and bone density through bone stimulation. The present study aimed to compare the effect of endurance training with varying intensities on the selected biomechanical properties of femurs in old male Wistar rats. 24 male Wistar rats (23 months old) with an average weight of 441.75 grams were randomly divided into 2 experimental and one control grpups: Moderate intensity continuous training (MICT, n = 8), high intensity Interval training (HIIT, n = 8), and control group (CG, n = 8). Moderate and high intensity endurance training sessions were held five days a week with 60-70% and   80-110% of the maximum speed) and high (maximum speed) for eight weeks, respectively. In the MICT and HIET groups, the duration and distance (volume of training) were the same and only the intensity of training differed. Forty-eight hours after the last training session, the rats underwent surgery and their femur removed. Three–point bending flexural test was used to determine the effects of training on modulation, maximum endurance, fracture energy, and femur strength in the rats. The statistical analysis was performed using one-way ANOVA test at P <0.05. The study results indicated that eight weeks of endurance training with varying intensities had no significant effect on modulation (p=0.198), bone strength (p=0.24), fracture energy (p=0.204), deformation-to-maximum strength (p=0.89), and femur strength (p=0.31), and that no significant difference was observed among the three groups. The biomechanical changes of the bone by such exercises require longer periods of training, which could be examined in future studies.