Effects of swimming exercise on the extinction of fear memory in rats.

We investigated the relation between swimming exercise and fear memory extinction. Rats that performed regular swimming exercise over 6 wk underwent fear conditioning. Twenty-eight days later, they were submitted to extinction tests. Swimming rats had enhanced extinction process throughout the 5 days of the extinction test compared with sedentary rats. This suggests that the swimming exercise accelerated the process of aversive memory extinction, reducing the expression of conditioned fear behavior. These results encourage further studies addressing the anxiolytic effects of exercise, with potential implications for anxiety disorders such as posttraumatic stress disorder. NEW & NOTEWORTHY We have shown that rats that performed regular swimming exercise over 6 wk had enhanced extinction process compared with sedentary animals. The swimming exercise may accelerate the process of aversive memory extinction, reducing the expression of conditioned fear behavior.