The effect of two types exercise therapy on bone mineral density and mechanical strength of osteoporotic male rats

Introduction: Osteoporosis is a systemic skeletal disease with a consequent increase in bone fracture. The purpose of this study was to determine skeletal changes induced by two types of exercise therapy in osteoporotic rats. Materials and methods: Among 30 male rats, 6 of them were selected as healthy group, Then Osteoporosis induced in other rats by intraperitoneal injection of 20% ethanol solution (3g/kg/day) for 3 weeks. Osteoporotic rats divided into 4 groups: Baseline, resistance, endurance and control (n=6). The two exercise groups completed 12 weeks of training, 5 days/week according to protocols. Endurance protocol included running exercise on a treadmill for, 12 m/min, 10 to 64 min/ day. The Resistance training protocol consisted of 8 series of climbing on the 110cm vertical ladder angled at 80º with weights tied to animal tail that was increased from the 50% of the body mass of the animal in the first series to100% in the eighth series. At the end of the training, the animals were euthanized, and the BMD of the femur and the L4 + L5 vertebrae were measured using DXA and tensile max load of the tibia and compression max load of the L5 were measured applying Zwick 2.5 machine. The collected data was analyzed using paired t and one way ANOVA tests. Results: The two groups of the exercises had significantly increased femur BMD compared to controls (P=0.035, P=0.001). L4+L5 BMD in resistance training and control groups was significantly greater than endurance group (P=0.001, P=0.001). The tibia tensile maximum load and L5 maximum load in resistance group were significantly greater than control (P=0.01, P=0.03). Conclusion: Resistance training induces more effective favorable changes in bone mineral status and bone strength as compared to endurance exercise in osteoporotic male rat.