Gait Speed and Survival in Older Adults | Hacker News Reader

Gait Speed and Survival in Older Adults

jama.jamanetwork.com

52 pointscolinprince24 comments

The basic result (old people who walk faster live longer than old people who hobble around) shouldn't come as a surprise at all: if you see two 75-year-old women at the mall, and one breezes by you like she has somewhere to be while the other shuffles past slowly, and you had to bet on which person had longer to live, you'd pick the fast one.

The interesting part is how strong the result is: "Predicted survival based on age, sex, and gait speed was as accurate as predicted based on age, sex, use of mobility aids, and self-reported function or as age, sex, chronic conditions, smoking history, blood pressure, body mass index, and hospitalization."

That's pretty remarkable. For a given age and sex, all of a person's headline medical information, taken together, is as good an indicator of longevity as their walking speed is.

Of course, the gait speed itself takes as inputs many of the rest of those factors. Smoking history, body mass index, and chronic joint or muscular conditions all pretty directly affect one's ability to walk fast. So gait speed turns out to be a very convenient, easily measured proxy for those other variables.

Right. I think the way to think of it is that in the context of survival, gait speed is a convenient and easily measured sufficient statistic for all this other stuff.

It's probably causal as well. Faster gait means walking is more convenient, so the subject does it more, so the subject gets more exercise.

Grip strength is similar predictor of longevity. Source: http://www.ncbi.nlm.nih.gov/pubmed/21541735

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.

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.

So the question becomes, to how young a person does this apply? How far back can be extrapolated? Is a slow 40something as meaningful a data point as a slow 70something year old?

I could see this becoming an interesting metric for targeted health care or health advertising, given the relative ease to determine gait speed from live video feeds. "IF gait speed < X, change display ad to 'see an orthopedist'"

My father is nearing 80 and in the last couple of years his gait his stiffened and slowed noticeably. Of course anybody has limited time left at 80, but it's interesting how much older he suddenly looked to an observer. 3 years ago he was confused with men in their 60s.

I think he suddenly felt older to himself as well, this year my parents finally decided to do a top-to-bottom review of their life-insurance, will and other estate issues.

So the takeaway from this is if you find yourself in a nursing home you better keep on trucking as fast as you can or the doctors will give up on you.

And thank you, colinprince, something that really does stimulate my intellectual curiousity, becoming a rarity on a front page that is starting to re-confirm my intellectual stances.

Walking faster now.

I wonder if they were just punning on http://en.wikipedia.org/wiki/The_Quick_and_the_Dead_%28idiom...

> Walking faster now.

Joke there, I suppose, since the authors did seem to find it applied for diagnosis (poor health slows people down, news at 11 ...).

Is it sad that my first thought before reading the article was the film with Sharon Stone?

I think it might be more interpreted as "staying vital, keeps people alive"

This reminds me of the following study, that had similar results but a better title:

  How fast does the Grim Reaper walk? 
  http://www.bmj.com/content/343/bmj.d7679

It's good to see more data backing the "more active == longer life" anecdote.

Obligatory xkcd link: http://xkcd.com/552/

(I have this one on a t-shirt.)

http://www.radiolab.org/2010/oct/08/

Radio Lab did a segment on how a cities average gait can predict many things about it.

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