Effects of endurance exercises on microarchitecture of proximal tibia in ovariectomized rats

Background: Appropriate endurance exercise can change bone mass density and strength of weight-bearing bones in both animals and humans, but its effects on the microstructure are not known. This study aimed to determine skeletal changes induced by the treadmill running endurance in ovariectomized adult mice.Methods: twenty-seven adult female rats were divided into experimental and control groups.(Each group consisted of 9 rats) and 9 rats were killed to determine baseline values. Experimental group performed the progressive running exercise for 8 weeks, 12 to 20 m/min, 10 to 59 min, 5 times per week. Microarchitecture of dense and spongy bone tissues in the proximal tibia epiphysis were measured by using a semi-automated image analysis system. Data was analyzed using t-student tests (P<0.05).Results: Running on treadmill causes a significant increase in the thickness and volume of spongy tissue and bone tissue was dense and spongy epiphysis upper tibia (P<0.05). Compared to control, treadmill running group showed significant difference in trabecular thickness and separation. Conclusion: Ovariectomy may decrease the microarchitecture properties of cortical tissue and especially, trabecular tissue in weight-bearing bones. Increasing bone strength induced by endurance exercise is mediated by changes in bon microarchitecture.