In other words, people who can’t walk or can barely walk are likely not that healthy - is probably a more intuitive theory than walking causes better health.
> a more intuitive theory than walking causes better health.
Why? Genuine question. In todays world, people drive themselves in cars and then park themselves in chair for hours. Then, on other end there are people having physical work that is literally body destroying - or people who literally go too much all in sports.
Why would it be unintuitive that normal walking around, mild exercise related to easy day to day activity would be better for health?
Obviously that will be the case to some extent, but it doesn't necessarily explain the whole effect, given this part:
> Dose-response meta-analysis indicated a strong inverse association, wherein the risk decreased linearly from 2700 to 17,000 steps per day.
I expect (especially in the US) that many or even most people who could walk several thousand steps a day, don't. They talk about the 70+ age group separately, but most of it is talking about the general population and says the relationship holds.
Of course, this meshes with what we already know about the clear links to exercise causing better health - not just things like balance, less risk of injury, bone density etc. in older people but for anybody prevention of or improvements to things like non-alcoholic fatty liver disease (combined with diet), improvements for those with metabolic syndrome, etc. which all contribute to a lot of early mortality.
