For six months, the women did twice weekly hour-long sessions of either aerobic exercise (brisk walking); resistance training such as weights, lunges and squats, or balance and muscle toning exercises.

Twenty-nine of the women had their hippocampus size checked again after completing these exercise programs. Those who did the full six months of aerobic training showed significant enlargement of the hippocampus, but this change did not occur in those from the other groups, according to a journal news release.

However, there was some indication that the increase in hippocampus size was associated with poorer verbal memory, the researchers reported.