Introduction: Osteoporosis is defined as a systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, resulting in increased risk of fracture. However, appropriate exercise for the prevention and treatment of osteoporosis has not been determined. The aim of this study was to determine the effects of two progressive loading training program on the bone properties of Osteoporotic rat models.

Materials & methods:  Among 30 male rats, 6 rats were separated as healthy group, Then Osteoporosis was induced in remaining rats by intraperitoneal injection of 20% ethanol solution (3g/kg/day) for four consecutive days for 3 weeks. 24 Osteoporotic rats were divided into 4 groups (n=6): baseline (As the baseline of the experimental groups), resistance training, endurance training and control. The two training groups completed 12 weeks of training program, 5 days a week according to protocol. The Endurance protocol includes running exercise on a treadmill for, 12 m/min, 10 to up 64 min/ day. The Resistance protocol consisted of 8 series of climbs on the 110-cm vertical ladder angled at 80º with weight tied to animal tail that was increased from the 50% of the body mass of the animal in the first series to 100% in the eighth series. At the end of the intervention, the animals were euthanized and the Bone mineral density (BMD) of the femur and the L4 +L5 were measured using dual energy x-ray absorptiometry (DXA). Microarchitectures of the proximal tibia metaphysis tissue were measured by using standard histomorphometric methods and with the motic software.

Findings: The endurance (p= 0.035) and resistance (p= 0.001) groups had significantly increased femur BMD compared to controls. L4+L5 BMD in resistance training and control was significantly greater than endurance group (p= 0.001,p= 0.001). only the resistance training had significantly increased the trabeculare percent (p= 0.018) and cortical thickness (p= 0.009) and had significantly decreased trabecular separation percent (p= 0.02)compared to controls. A number of osteocyte in both endurance and resistance groups was significantly greater than that in control group (p= 0.03, p= 0.002).

Discussion & Conclusions: Resistance training induces more effective favourable changes in bone mineral status and pathology as compared to endurance training in osteoporotic male rats.