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Comment by rjknight | Hacker News Reader

This is not saying that adopting a faster gait speed will cause you to live longer. It's saying that a person's gait speed is a good indicator of how much longer they're likely to live. To me, it seems likelier that there's a common factor which causes both slower gait speed and death, so how fast you try to walk isn't the important factor.

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My guess would be the common factor is likely a person's general cumulative state of health (e.g. obesity level, presence of chronic injury, respiratory efficiency, etc). Would be fascinating to study this more.

But what if by walking faster you improve the common factor? What if it's just that gait speed is a symptom of poor heath, but by attempting to walk faster (maybe even by going for more walks) you actually improve your health?

The questions you ask are interesting, but not answered in any way by the linked study.

Unlikely. Or the effect might be minimal.

It's pretty common-sense that healthy people will already have a faster gait. I mean for lots of people who are about to die, their gait speed is probably zero because you can't even walk. Your average person doesn't even spend much time exercising, and this study is about average folks, so it's saying that average folks with a faster gait live longer. Most of them don't even exercise.

Exercise doesn't have to be intentional. I think this is probably partly causal: https://news.ycombinator.com/item?id=5914630

Pop media is awful about these correlation versus causality studies.

I was planning to post a sarcastic "Great! Now I can live longer just by walking fast!" comment, but your comment makes that pointless. Damn.

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