7 ms·

Daily Step Count and All-Cause Mortality: A Dose-Response Meta-analysis

76 points by caaqil 5y ago

toxik 5y ago
The link between walking and all cause mortality seems less interesting than, say, stress levels. People don’t go for a walk to cheat death, it’s because they’re in need of a breather.
- stephen_g 5y ago
  I know lots of people who walk regularly because they know it's good for their general health and wellbeing... It is true though that it can be really enjoyable and help to de-stress too, but that's not the only reasons people do it.
  - toxik 5y ago
    Right, so the link to general health and well-being would be interesting - not all-cause mortality.
    - pjerem 5y ago
      General health and well-being is probably highly correlated with average longevity though. Stress is a pretty high factor mortality risk, so if walking reduces it, it's probably a real win.
      - toxik 5y ago
        There you snuck that word in- 'probably'. Maybe. But that's not what the paper looked at.
    - stephen_g 5y ago
      "So I don't die early" is a large part of "general health and wellbeing" for the purposes of my comment.
- LorenPechtel 5y ago
  A breather? Most of the time when I'm walking it's with a pack on my back heading into the wilderness.
anovikov 5y ago
What if the difference is because of pre-existing health state and conditions of those people i.e. those who's health is poor enough they are likely to die soon, just don't have energy to walk a lot? Meaning, this may be a classic case of correlation which is not a causation. I would speculate that in particular case of the U.S., there is also a social factor in play that is, people with different health outcomes and longevity are also people from different social classes who may or may not have time and space/environment appropriate for these activities?
- EugeneG 5y ago
  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.
  - stephen_g 5y ago
    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.
    - scotty79 5y ago
      Healthier people might have more reasons and energy to move beyond what's necessary
  - watwut 5y ago
    > 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?
scotty79 5y ago
It's really hard to report on correlation without implying causality. So whenever you see research popping up in your news feed just flip the order of statements in the title. "People at greater risk of dying walk less" Then read the paper carefully for any signs of something that doesn't fit this flipped version. "Correlation consists even when controlled for smoking and comorbidities" It still can be true because smoking is just one factor out of thousands factors contributing to early deaths, and comorbidities probably bunched up so many unrelated stuff together that you could control for some random stuff and get really close results. And even if they accounted for all the comorbidities precisely still people with each might be in different condition and those farther from death might want to walk more.
- danuker 5y ago
  Agree. But even this meta-study of 175370 person-years only encountered 2310 deaths. Imagine what it would cost to make an interventional study and track how accurately people report they are walking. But even the credibility of this is somewhat higher than a pure "correlation" or cross-section study, because the dying is in the future, compared to when the walking is counted ("prospective" cohort studies). And there is no possible blind study, because the participants know they are walking, and you can't have a "placebo walk".
  - feral 5y ago
    > no possible blind study, Not sure I agree with this. I am definitely not saying this should be done, but as a thought experiment: Imagine you worked for Fitbit, and could choose to undercount steps slightly. You have a cohort of users who will walk each day until they reach 10k steps. You undercount steps for a random subset so that they end up walking 10.5k. You repeat this experiment so you make the folks with a 5k goal actually walk 5.5k, etc This is a pretty good blinded study. The difference is slight enough that the users don't notice the extra increase in distance consciously. (Obviously you have to take into account the risk of churning people from the service somehow.) If you were to check all cause mortality somehow (look up public death records? Some other way?) That would seem like a pretty good study design. Again, perhaps unethical to do this without consent; but not impossible; you could ask a cohort of users to opt in to this sort of study. If the claim is that it's distant dependent, this would likely take you a lot closer to causality.
reedf1 5y ago
It is frustrating to link this to a unit as unspecific as "steps". It's like modern day "hands" or something. I would think it would be incredibly difficult to come to any conclusion before decoupling weight, terrain, shoe material, stride, altitude, etc. In addition, I've seen people get more unhealthy after taking up the dogma of "steps" as they are now tracking their normal-everyday-routine and using it to justify their lack of medium/high-intensity exercise. "Bing! I closed a ring. I can skip the gym today."
- Tenoke 5y ago
  Steps doesn't seem to be a bad measurement as it naturally partially controls for height, and is easy to measure. Not to mention the results are there even when they account for "body mass index, alcohol drinking, smoking status, step intensity, and pre-existing comorbidities" and more. Sure, the results will be noisy but you should still expect to see the effect with a large sample size which this has. Also, I'm somewhat doubtful that it's common for people to do less exercise after starting to count steps and if anything I'd expect a positive correlation between people becoming more active by walking more and picking up other forms of exercise.
  - netizen-936824 5y ago
    Where does height come into play if it was not controlled for
    - thejteam 5y ago
      If the study were asking for distance instead of steps, then taller people will naturally go further in fewer steps. But, at least according to these studies, it is the act of stepping that improves health and not traveling distance.
      - netizen-936824 5y ago
        My apologies, I think in phrased that poorly. The parent comment I replied to stated: >Steps doesn't seem to be a bad measurement as it naturally partially controls for height My question is why would height matter at all in this context if it were not controlled for? Is height associated with mortality?
stefs 5y ago
for a summary and thoughts on matters of sports and health like this i trust greg nuckols on strongerbyscience: https://www.strongerbyscience.com/research-spotlight-walking/ https://www.strongerbyscience.com/research-spotlight-walking...
linsomniac 5y ago
As someone who, over the last year, has gone from sedentary, in front of the computer lifestyle, to jogging 5K 3 times a week on the treadmill and getting 10K steps per day half the days in the last month... My wife and I both feel 20 years younger. The change brought on through a number of lifestyle changes has been dramatic and basically entirely positive. Yes, steps is only one component of it. But: I could also see that steps probably do correlate with other healthy lifestyle choices. Just making time in the day for a half hour walk or an hour on the treadmill is an indicator of prioritizing some health choices over other things.
- stephen_g 5y ago
  Yes, I agree! I've gone from not doing enough exercise to a level where I'm pretty happy too (hope to work up to doing 10K at a decent pace but I can do 5K without too much difficulty now). I'm really enjoying doing swimming (1.5 to 2K a week), jogging not as much at first but it's growing on me as I'm getting fitter! Having made the effort myself over the last year and a half, it's pretty surprising seeing so many 'correlation is not necessarily causation' people here (yes, we all understand the concept) basically imply that everybody probably does as much exercise as they possibly can for their level of health, so it might all just be a correlation... It seems quite clear from general observation that a huge proportion of the population could exercise much more than they do, but don't. (I definitely didn't!). It also seems surprising because that argument basically seems to dispute the idea that exercise makes you healthier... There's definitely both correlation and causation happening. But walking and jogging is really good for health, people shouldn't just write it off! Here's a good study on walking interventions and positive health outcomes, for example - https://pubmed.ncbi.nlm.nih.gov/25601182/ https://pubmed.ncbi.nlm.nih.gov/25601182/
tuukkah 5y ago
Lots of focus on the step count while IMT/IMST breathing muscle training seems much more convincing (for the young and healthy as well as for the frail): "5-minute breathing exercise lowers blood pressure better than working out, medication" https://news.ycombinator.com/item?id=27747943 https://news.ycombinator.com/item?id=27747943 "Thanks HN: For Me, Breathing exercise for High Blood Pressure is Working" https://news.ycombinator.com/item?id=27980060 https://news.ycombinator.com/item?id=27980060
- tuukkah 5y ago
  Breathing resistance training might even reduce the need of Covid emergency care and the long Covid symptoms: "Respiratory Muscle Performance Screening for Infectious Disease Management Following COVID-19: A Highly Pressurized Situation" https://www.amjmed.com/article/S0002-9343(20)30347-8/fulltext https://www.amjmed.com/article/S0002-9343(20)30347-8/fulltex...
- Tenoke 5y ago
  The IMT study this is based on is tiny compared to the meta-analysis for steps. It also only tested blood pressure and for a short amount of time compared to all-cause mortality over years in the meta-analysis.
mleonhard 5y ago
Other possible sources of bias: People who walk more live in more walkable neighborhoods and are likely more wealthy, live in places with less air pollution, have less traffic noise disturbing their sleep, and travel fewer miles in cars thereby reducing risk of car accidents.
- nerdponx 5y ago
  And wealth also possibly means access to better nutrition, better healthcare, and lower stress overall.

76 points by caaqil 5y ago

The link between walking and all cause mortality seems less interesting than, say, stress levels. People don’t go for a walk to cheat death, it’s because they’re in need of a breather.

stephen_g 5y ago
I know lots of people who walk regularly because they know it's good for their general health and wellbeing... It is true though that it can be really enjoyable and help to de-stress too, but that's not the only reasons people do it.
- toxik 5y ago
  Right, so the link to general health and well-being would be interesting - not all-cause mortality.
  - pjerem 5y ago
    General health and well-being is probably highly correlated with average longevity though. Stress is a pretty high factor mortality risk, so if walking reduces it, it's probably a real win.
    - toxik 5y ago
      There you snuck that word in- 'probably'. Maybe. But that's not what the paper looked at.
  - stephen_g 5y ago
    "So I don't die early" is a large part of "general health and wellbeing" for the purposes of my comment.
LorenPechtel 5y ago
A breather? Most of the time when I'm walking it's with a pack on my back heading into the wilderness.

anovikov 5y ago

What if the difference is because of pre-existing health state and conditions of those people i.e. those who's health is poor enough they are likely to die soon, just don't have energy to walk a lot? Meaning, this may be a classic case of correlation which is not a causation. I would speculate that in particular case of the U.S., there is also a social factor in play that is, people with different health outcomes and longevity are also people from different social classes who may or may not have time and space/environment appropriate for these activities?

EugeneG 5y ago
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.
- stephen_g 5y ago
  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.
  - scotty79 5y ago
    Healthier people might have more reasons and energy to move beyond what's necessary
- watwut 5y ago
  > 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?

scotty79 5y ago

It's really hard to report on correlation without implying causality. So whenever you see research popping up in your news feed just flip the order of statements in the title. "People at greater risk of dying walk less" Then read the paper carefully for any signs of something that doesn't fit this flipped version. "Correlation consists even when controlled for smoking and comorbidities" It still can be true because smoking is just one factor out of thousands factors contributing to early deaths, and comorbidities probably bunched up so many unrelated stuff together that you could control for some random stuff and get really close results. And even if they accounted for all the comorbidities precisely still people with each might be in different condition and those farther from death might want to walk more.

danuker 5y ago
Agree. But even this meta-study of 175370 person-years only encountered 2310 deaths. Imagine what it would cost to make an interventional study and track how accurately people report they are walking. But even the credibility of this is somewhat higher than a pure "correlation" or cross-section study, because the dying is in the future, compared to when the walking is counted ("prospective" cohort studies). And there is no possible blind study, because the participants know they are walking, and you can't have a "placebo walk".
- feral 5y ago
  > no possible blind study, Not sure I agree with this. I am definitely not saying this should be done, but as a thought experiment: Imagine you worked for Fitbit, and could choose to undercount steps slightly. You have a cohort of users who will walk each day until they reach 10k steps. You undercount steps for a random subset so that they end up walking 10.5k. You repeat this experiment so you make the folks with a 5k goal actually walk 5.5k, etc This is a pretty good blinded study. The difference is slight enough that the users don't notice the extra increase in distance consciously. (Obviously you have to take into account the risk of churning people from the service somehow.) If you were to check all cause mortality somehow (look up public death records? Some other way?) That would seem like a pretty good study design. Again, perhaps unethical to do this without consent; but not impossible; you could ask a cohort of users to opt in to this sort of study. If the claim is that it's distant dependent, this would likely take you a lot closer to causality.

reedf1 5y ago

It is frustrating to link this to a unit as unspecific as "steps". It's like modern day "hands" or something. I would think it would be incredibly difficult to come to any conclusion before decoupling weight, terrain, shoe material, stride, altitude, etc. In addition, I've seen people get more unhealthy after taking up the dogma of "steps" as they are now tracking their normal-everyday-routine and using it to justify their lack of medium/high-intensity exercise. "Bing! I closed a ring. I can skip the gym today."

Tenoke 5y ago
Steps doesn't seem to be a bad measurement as it naturally partially controls for height, and is easy to measure. Not to mention the results are there even when they account for "body mass index, alcohol drinking, smoking status, step intensity, and pre-existing comorbidities" and more. Sure, the results will be noisy but you should still expect to see the effect with a large sample size which this has. Also, I'm somewhat doubtful that it's common for people to do less exercise after starting to count steps and if anything I'd expect a positive correlation between people becoming more active by walking more and picking up other forms of exercise.
- netizen-936824 5y ago
  Where does height come into play if it was not controlled for
  - thejteam 5y ago
    If the study were asking for distance instead of steps, then taller people will naturally go further in fewer steps. But, at least according to these studies, it is the act of stepping that improves health and not traveling distance.
    - netizen-936824 5y ago
      My apologies, I think in phrased that poorly. The parent comment I replied to stated: >Steps doesn't seem to be a bad measurement as it naturally partially controls for height My question is why would height matter at all in this context if it were not controlled for? Is height associated with mortality?

stefs 5y ago

for a summary and thoughts on matters of sports and health like this i trust greg nuckols on strongerbyscience: https://www.strongerbyscience.com/research-spotlight-walking/ https://www.strongerbyscience.com/research-spotlight-walking...

linsomniac 5y ago

As someone who, over the last year, has gone from sedentary, in front of the computer lifestyle, to jogging 5K 3 times a week on the treadmill and getting 10K steps per day half the days in the last month... My wife and I both feel 20 years younger. The change brought on through a number of lifestyle changes has been dramatic and basically entirely positive. Yes, steps is only one component of it. But: I could also see that steps probably do correlate with other healthy lifestyle choices. Just making time in the day for a half hour walk or an hour on the treadmill is an indicator of prioritizing some health choices over other things.

stephen_g 5y ago
Yes, I agree! I've gone from not doing enough exercise to a level where I'm pretty happy too (hope to work up to doing 10K at a decent pace but I can do 5K without too much difficulty now). I'm really enjoying doing swimming (1.5 to 2K a week), jogging not as much at first but it's growing on me as I'm getting fitter! Having made the effort myself over the last year and a half, it's pretty surprising seeing so many 'correlation is not necessarily causation' people here (yes, we all understand the concept) basically imply that everybody probably does as much exercise as they possibly can for their level of health, so it might all just be a correlation... It seems quite clear from general observation that a huge proportion of the population could exercise much more than they do, but don't. (I definitely didn't!). It also seems surprising because that argument basically seems to dispute the idea that exercise makes you healthier... There's definitely both correlation and causation happening. But walking and jogging is really good for health, people shouldn't just write it off! Here's a good study on walking interventions and positive health outcomes, for example - https://pubmed.ncbi.nlm.nih.gov/25601182/ https://pubmed.ncbi.nlm.nih.gov/25601182/

tuukkah 5y ago

Lots of focus on the step count while IMT/IMST breathing muscle training seems much more convincing (for the young and healthy as well as for the frail): "5-minute breathing exercise lowers blood pressure better than working out, medication" https://news.ycombinator.com/item?id=27747943 https://news.ycombinator.com/item?id=27747943 "Thanks HN: For Me, Breathing exercise for High Blood Pressure is Working" https://news.ycombinator.com/item?id=27980060 https://news.ycombinator.com/item?id=27980060

tuukkah 5y ago
Breathing resistance training might even reduce the need of Covid emergency care and the long Covid symptoms: "Respiratory Muscle Performance Screening for Infectious Disease Management Following COVID-19: A Highly Pressurized Situation" https://www.amjmed.com/article/S0002-9343(20)30347-8/fulltext https://www.amjmed.com/article/S0002-9343(20)30347-8/fulltex...
Tenoke 5y ago
The IMT study this is based on is tiny compared to the meta-analysis for steps. It also only tested blood pressure and for a short amount of time compared to all-cause mortality over years in the meta-analysis.

mleonhard 5y ago

Other possible sources of bias: People who walk more live in more walkable neighborhoods and are likely more wealthy, live in places with less air pollution, have less traffic noise disturbing their sleep, and travel fewer miles in cars thereby reducing risk of car accidents.

nerdponx 5y ago
And wealth also possibly means access to better nutrition, better healthcare, and lower stress overall.