Effects of Aerobic Exercise on the Hippocampus in Late Adulthood After one year of regular aerobic exercise—simply walking three times a week—elderly participants (purple line) increased the size of their left and right hippocampus (brain region, highlighted in yellow) by an average of 2 percent. In contrast, the stretching-and-toning group (orange line) showed about a 1.5 percent decline in the hippocampal volume, which is normal for this age group.

Erickson et al. Exercise training increases size of hippocampus and improves memory. PNAS 2011 108 (7) 3017-3022; published ahead of print January 31, 2011, doi:10.1073/pnas.1015950108. Image courtesy Kirk Erickson.
Source: Erickson, Kirk I.; Voss, Michelle W.; Prakash, Ruchika S.; Basak, Chandramallika; Szabo, Amanda; Chaddock, Laura; & others. (2011). Exercise training increases size of hippocampus and improves memory. Proceedings of the National Academy of Sciences, 108, 3017–3022.