This is how I look for what you're looking for:

> A human CNS study comparing individuals with high versus low or high versus medium lifetime activity^16 were the first and third top matches

There's a PDF of citation 16: https://mind.uci.edu/wp-content/uploads/2019/06/1-s2.0-S0197458019300594-main.pdf

...in which:

> All tissues were obtained from the midhippocampus region containing all hippocampal subfields. Participants were diagnosed as cognitively intact based on annual assessment of cognitive status using a battery of 19 cognitive tests, at which time they were additionally assessed for other lifestyle factors including cognitive frequency, social frequency, and depression, among other variables (Bennett et al., 2012). Participants underwent annual assessment of physical activity using actigraphs worn continuously over multiple days

...and here we find the full text of Bennett et al., 2012: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3439198/

but there's no actigraphy data included in the paper, so likely the authors just had it on hand from this earlier data collection, and used it for the parent study that was posted.

The most you can glean from this is that having a high level of physical activity confers some benefit compared to sedentary behavior.