[giwook]

I'm not convinced.

I may be misunderstanding how the study was conducted, but it sounds like a more reasonable conclusion to draw from the study is that those who tend to have better health outcomes and longer healthspans/lifespans are the ones who also are willing to prioritize their health and physical fitness and are willing to spend this much time on exercise.

The average age of participants in the study was 57, so you're already narrowing in on a very specific and pretty narrow subset of the population when you're looking at seniors who are also spending 10 hours a week on exercise.

While 560-610 minutes of moderate to vigorous physical activity certainly helps, I'd think these are individuals who are generally abstaining from smoking, will try to eat healthy at least moderately often, stay away from overconsumption of fast food or alcohol, etc.

Basically, it sounds like there is a degree of correlation here between habits and outcomes that is being conflated with causation.

[ianbooker]

Confounders are included and therefore controlled for, and causality can be assumed since the DV is an event/hazard. This is also the reason you end up with the seemingly high average...