Walk More, Live More?
Study review on daily step count and all cause mortality
Study reviewed: Daily Step Count and All-Cause Mortality: A Dose-Response Meta-analysis of Prospective Cohort Studies
I recently looked at a new paper that meta-analyzed (looked at a group of relevant studies) the effect between daily step count and all cause mortality.
A couple things:
This was observational data from prospective cohorts over anywhere from 4–10 years. All these subjects were free living, so this is not what we would call a controlled trial.
The researchers did stratify for certain qualities in their subjects. All studies controlled for BMI. Some were done on only men, some only on women. Most controlled for smokers or folks who averaged a certain level of alcohol intake.
With that being said, data like this is very valuable, but it is unfair for us to expect them to control all variables for these people for 10 years.
The reason why I bring this up, is because some folks over state their conclusions from observational data to infer causation. Which should not be done in most cases.
Data like this can help us make correlations, association and links. Not infer causations. So this isn’t to say walking literally causes life extension. Rather, higher step counts do correlate with reductions in all cause mortality.
Methods
This paper broke down 7 studies that all had adults above the age of 18 years old.
There was a total of 28,141 subjects spanning several countries including the USA, Japan, Norway, Australia and the UK.
The average age for all studies was either mid 50’s or early 70’s.
Subjects were measured using accelerometers or pedometers. Then, they were taken baseline step targets across 7 days for most of the studies.
After that they were followed up on between the range 4 years and 10 years.
Findings
The researchers found that past 2700 steps, there was a 12% reduction in rates of all cause mortality (death by any cause) for every 1000 additional steps up to around 16,000 steps.
This does’t mean more than 16,000 wasn’t beneficial, it’s just that they didn’t have enough subjects hitting it to get good data.
You’ll see above that the back solid line represents the dose-response between steps per day and risk of all cause mortality.
So compared to 2700 steps per day, folks who averaged 16,000 steps per day showed a 66% decrease in risk of all cause mortality.
Interpretation
This is why I brought up the first point around how to look at data like this. It would be unfair to say walking 16,000 per day causes a 66% decreased rate of death.
More so, it is linked or associated within this data set and this population.
There is also some potential for reverse causation here too.
A great example of reverse causation being misinterpreted is when people say drinking diet soda makes you overweight, it doesn’t (this may sound ludicrous, but I’ve heard it). Yes, there is an association between consuming more diet beverages and being overweight, but it’s more likely that being overweight causes you to consume more diet beverages than it is that diet beverages cause you to be overweight. As the latter would defy the laws of physics (they have zero calories) and the former is the result of the intended market of consumers (people wanting to lose weight) consuming a product that is marketed to them.
Healthier folks just might be able to walk more and have the time and ability to do so. So the walking could be a by product of better health and actually just a part of this positive feedback loop.
Affluence/socioeconomic status could also impact this.
An overstressed, single working parent in a less safe neighbourhood just might not have the luxury to go for a nice evening stroll than some other people might.
In that context, you can’t really say the lack of walking is that person’s main health concern and that walking more will just ultimately improve their health.
This is just one example of how to misconstrue observational data.
How you can best look at this is to compare to your own life.
Walking more is most likely a net positive.
This doesn’t mean you have to get 16k steps per day.
If you currently get 3000, let’s shoot for 4000 or even 5000. Based off this data, that could potentially reduce all cause mortality risk by up to 24%. That would be awesome.
It also may not just be the walking. It could be the potential feedback loop the walking could bring.
Example:
-You walk more, you expend more energy. Potentially a good thing.
-You walk more, so you get outside more and perhaps nature reduces your stress.
-Maybe you walk with a friend and feel deeper connection.
-Maybe when you walk more you reflect on your life more and practice gratitude.
-Higher activity levels has been shown to help moderate appetite, so perhaps you are more in tuned with your appetite and managing your diet better.
etc. etc.
All of these other factors could be piling on additional benefits than walking excusively could.
You get the point.
Regardless, I think this was a great study done by these researchers.
In summary, walking does have a strong inverse association with higher step counts and reductions in all cause mortality.
Specifically, this data showed a 12% reduction with every 1000 steps from 2700 to 16000.
If you can, you would probably benefit from walking more. So let’s get to stepping!
Cheers,
-Coach Dylan🍻
References:
Daily Step Count and All-Cause Mortality: A Dose-Response Meta-analysis of Prospective Cohort Studies
https://pubmed.ncbi.nlm.nih.gov/34417979/
2. Does low-energy sweetener consumption affect energy intake and body weight? A systematic review, including meta-analyses, of the evidence from human and animal studies
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4786736/