> brains that looked nearly a year younger

Seems like a pretty small effect - if I'm 58 and I have the brain of a 57 year old, and to achieve that I did an entire year of exercise (as was done in this study) ... you'd have to evaluate it against many other things to decide if that was really the easiest way to achieve that result.

I'm always suspicious of small effect sizes even when they are statistically significant. It just seems like so many confounders could bring about the effect. Here I'd wonder if just the mental challenge of achieving that sustained exercise over a whole year was responsible, since generally speaking, any mental challenge you undertake on a regular bases improves overall cognition.

They try to argue their way around this:

> "Even though the difference is less than a year, prior studies suggest that each additional 'year' of brain age is associated with meaningful differences in later-life health,"

But it just begs the question, if you think that then go measure those things with your study.

Of course I'm not in any way arguing against exercise. Adding at least a baseline level of exercise into your lifestyle is the most impactful health intervention anybody can do after age 40 I believe.

>But it just begs the question, if you think that then go measure those things with your study.

Because randomized control, multi-year, longitudinal studies into behavioral interventions in human beings are incredibly annoying and expensive to run if you want to account for the risk of drop outs and/or non-compliance. They hosted twice weekly aerobic exercise classes for the experimental group (dozens of people) for a year! That’s not cheap by any means