Abstract: Objective To investigate the effects of aerobic exercise pre-treatment combined with hyperbaric oxygen (HBO) on cognition,blood brain barrier and oxygen free radicals after cerebral isehemia reperfusion in rats.Methods Seventy-five male Sprague-Dawley rats were randomly divided into 5 groups:the sham group,the model group,the aerobic exercise pre-treatment group,the HBO group,and the aerobic exercise pretreatment + HBO group,each consisting of 15 animals.The cerebral ischemia-reperfusion model was established by using the modified Pulsinelli four-blood-vessel-occlusion method.The water maze test was used to evaluate the cognitive function of rats in each group,and the Evans blue (EB) method and Zo-1 expression level were used to evaluate blood brain barrier permeability,and the activity of superoxide dismutase (SOD) and malondialdehyde (MDA) level in hippocampus were measured with the hydroxylamine method and TBA method.Results The cognitive function of the rats in the model group was impaired,as compared with that of the sham group(P <0.05),EB concentration and the expression level of Zo-1 were increased,and SOD activity was decreased and MDA level was increased (P < 0.05).Aerobic exercise pre-treatment plus HBO exposure could significantly improve the cognitive function of rats,reduce the concentration of EB,as well as the expression level of Zo-1.Furthermore,it could increase SOD activity,and and MDA concentration,plus best effects were achieved in the aerobic exercise pretreatment + hyperbaric oxygen treatment group(P < 0.01).Conclusions Moderate or proper aerobic exercise combined with HBO therapy before establishment of the cerebral ischemia-reperfusion model could significantly improve cognitive function and blood brain barrier,inhibit oxidative stress,and best effects were seen in the aerobic exercise pretreatment + hyperbaric oxygen treatment group.