Background: Exercise can counteract the negative effects of stress, but variations in exercise protocols and intensities have generated different results. The purpose of this study was to investigate the effect of immobilization stress on cognitive performance and the moderating role of exercise.

Materials and Methods: In this experimental study, adult Albino-Wistar rats were randomly assigned to 5 groups. The animals underwent immobilization stress (2 hours per day×7 day), exercise (30 minutes per day×7 day), or no intervention. The rats were trained and tested using Morris water maze.

Results: The control group had better performance than the stress group in acquisition (p<0.01) and recall (p<0.05) in Morris water maze. There was not a significant difference between exercise-stress and control groups in water maze performance. Stress increased corticosterone levels (p<0.001), but exercise had a significant effect on decrement of corticosteron levels (p<0.001). Also, despite the absence of a significant difference between sham and exercise groups in the acquisition stage, the exercise group had a better performance in the recall stage (p<0.05).

Conclusion: Immobilization stress can impair acquisition and mild exercise has a protective effect against stress-induced negative effects. Corticosterone may be a major mediator in the protective effect of exercise against stress-induced cognitive impairment. In addition, the role of exercise in retrieval of past experiences is more prominent than their acquisition.