Effects of treadmill exercise training on biomechanical properties of bone in a rat model of type 2 diabetes

Objective To study the influence of different intensities of treadmill exercise training on bone biomechanical properties and the bone healing in type 2 diabetic model rats.Methods Fifty-two healthy 8-month-old male Sprague-Dawley rats were randomly divided into a control group (n =10) and a type 2 diabetic model group (n =42).Type 2 diabetes was modeled in rats of the model group by feeding feedstuff containing high glucose,fat and energy food for 4weeks,followed by a single intra-abdominal injection of streptozotocin.Thirty model rats were then randomized into 3 subgroups:type 2 diabetes group,a mild exercise group and a moderate exercise group.Different intensities of treadmill training protocols was administered accordingly for 8 weeks.The biomechanical indices of the femur bone including maximum load and stress,module and energy was measured with mechanical testing instrument.Results Compared with the control group,both maximum load and energy were decreased significantly in type2 diabetes group [(148.5±17.8)N vs (192.3±43.4)N] for maximum load,and (51.38 ±13.7)mJ vs (82.0 ± 30.8) mJ for maximum stress] (P ＜ 0.05,P ＜ 0.01).Compared with the type 2 diabetes group,maximum load and stress were increased significantly in the mild and moderate exercise groups(P ＜ 0.05,P ＜ 0.01).Maximum load and energy were improved more in the moderate exercise group than in the mild exercise group [(184.1 ± 26.6)N vs (165.4±21.5)N for maximum load and (83.59 ±29.96)mJ vs (62.33 ±14.32)mJ for maximum stress] (P ＜ 0.05).Conclusions A significant decrease of the bone biomechanical properties was observed in rats with experimental type 2 diabetes,which could be alleviated by treadmill exercise training. Key words: Aerobic exercise;  Type 2 diabetes;  Biomechanical;  Exercise intensity