Effect Of Exercise And Caloric Restriction On Bone Density And Biomechanical Properties And Biomarkers Of Bone Metablism In Obese Rats

Objective:these findings have important implications in designing an appropriate weight-loss therapy program to offset the adverse of weight loss on bone.Methods:After the models of obesity were prepared successfully, thirty-two fat rats were randomized to 1 of 4 groups for 30 days:caloric restriction(CR) group(n=7),regular exercise(EX) group(n=8),caloric restriction + exercise group(n=8),or a control group(n=7).They were continued to be fed with high fat diet,CR rats were fed to the 80%mean daily intake of control rats.Body weight was measured every week,The exercise form is swimming and they swam for 5 weeks(6d/w,90min/d).60 hours after last exercise,all rats were killed by decapitation.Weight,Lee's index were detected.Blood samples were collected and serum was separated by centrifugation(16,000×g for 10min) and frozen at-70℃until determination of biomarkers of bone turnover.Long bones (femur) of each rat were removed,cleaned of soft tissue,wrapped in saline-soaked gauze and stored at 4℃until analyzed for bone density and biomechanical testing within 24h.Conclusion:①CR or ER can reduce the weight of the obese SD rats significantly(P＜0.01),there was an interaction between them(P＞0.05).②CR or ER is not enough to significantly reduce the length and volumetric densitometer of the obese rat's femur(P＞0.05).③The maximum load,elastic load and general energy absorption of the femur were lower in CR group then control group(P＜0.01),The maximum deformation,elastic deformation and bending rigidity coefficient of the femur were significantly affected by EX or CR and there was an interaction between EX and CR(P＜0.01 or 0.05)。④Serum P and ALP of the CR group were decreased by CR significantly(P＜0.01),but serum Ca and TRACP were not affected by CR(P＞0.05),CR reduce the bone formation of these obese rats.Serum biomarkers of bone turnover were not significantly affected by EX (P＞0.05).