Reference
Kirk Erickson
The widely quoted finding that a year of walking grew the hippocampus by about 2% is from the trial he led.
Erickson led a randomised trial in which 120 older adults either walked three times a week for a year or did a stretching and toning programme instead. Anterior hippocampal volume rose by about 2% in the walking group and fell by about 1.4% in the comparison group, which is roughly the amount this part of the brain is otherwise expected to lose in a year or two at that age.
What the trial is usually made to say goes further than what it showed. A letter published in the same journal argued that the memory improvement could not be attributed either to the aerobic training or to the change in hippocampal volume, because the two groups did not differ significantly on the memory measure and the volume change did not track memory within the exercise group. We cite the structural finding, which is the part that held, and not the headline that a year of walking makes you remember better.
Referenced work
- Exercise training increases size of hippocampus and improves memory (PNAS, February 2011) reference
- Failure to demonstrate that memory improvement is due either to aerobic exercise or increased hippocampal volume (PNAS, reply to the above) reference
Elsewhere
Listed here because we name Kirk Erickson in our writing. We are not affiliated with them and this page is our summary, not theirs.