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Background and Aim: Osteoporosis is a complex disease characterized by  loss of bone mass, resulting in bone weakness and an increase in susceptibility to fractures. The aim of the current study was to determine skeletal changes induced by two progressive loading training programs on the bone properties of osteoporotic male rats.

Materials and Methods: This experimental study was done on 30 Wistar male rats having mean weight of 180-200 g. They were divided into .5 equal groups. In the experimental group, osteoporosis was induced through intraperitoneal injection of 20% ethanol solution (3g/kg/day) for four consecutive days for 3 weeks. The rest of the groups were  baseline group (pre test), resistance training, endurance training, and the control. The two training groups completed 12 five-day weeks of training program. according to resistance or endurance protocols. The other 6 rats were considered as the healthy group without any intervention . At the end of the intervention, the animals were killed and their bone mineral density (BMD) of the femur and  L4, L5 were measured. Tensile max load of the left tibia and compression of the L5 vertebra were measured using mechanical tests.

Results: The endurance (P= 0.035) and resistance (P= 0.001) groups femur BMD had significantly increased compared to that of the control . L4, L5 BMD in resistance training and control was significantly greater than that of endurance group (P= 0.001,P= 0.001). The tensile maximum load of the tibia and compression of the L5 in the resistance group was significantly greater than the control (P=0.01,P=0.03).

Conclusion: Resistance training, compared to endurance training, can induce more effective favourable changes in bone mineral status and bone strength.