It’s How You Walk -- Not Just Your Step Count -- That Matters

[Northerner]

Ten thousand steps a day. I know you've heard the number. A number that reminds us to get up, move around, walk to the store instead of drive there.

Ten thousand steps is achievable, but not precisely easy, at least if you have a job that keeps you sitting in front of a computer for 8 hours a day. And, with smartphones in our pockets, knowing if you've hit that magic mark is trivial.
As far as health interventions go, encouraging people to walk 10,000 steps a day is pretty low-risk, and the price is certainly right. But the benefit is harder to tease out. That is why I got intrigued by a new study in JAMA Internal Medicine that looked at the link between steps taken and the risk for death and found something novel. It's not just how many steps you take. It's how you take them.

The study leveraged the UK Biobank cohort — a longitudinal study of British adults that collects a lot of data over time, but does not collect step counts.

So the authors emailed over 200,000 cohort participants, asking them if they'd wear a step counter — actually, a pretty fancy step counter called an Axivity AX3 accelerometer — 24 hours a day for 7 straight days.

It’s How You Walk -- Not Just Your Step Count -- That Matters

When you're trying to reach 10,000 a day, remember this.

www.medscape.com

 

[Bruce Stephens]

Here's another link https://chof360.com/its-how-you-walk-not-just-your-step-count-that-matters/

So faster steps are better than slower ones, and (perhaps the same thing) purposeful steps are better than casual ones.

(I remember being a participant in this one, and the tracker was pretty light so won't have changed behavior for that reason.)

 

[Eddy Edson]

Here's another link https://chof360.com/its-how-you-walk-not-just-your-step-count-that-matters/

So faster steps are better than slower ones, and (perhaps the same thing) purposeful steps are better than casual ones.

(I remember being a participant in this one, and the tracker was pretty light so won't have changed behavior for that reason.)

The paper: https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2796058

I looked at this a couple of days ago & just couldn't get my head around the cadence data. Eg this chart from Fig 1:



Briefly, 100 steps/min in this paper and elsewhere is taken as the cut-off for "moderate" exercise (citing the work of Tudor-Locke who seems to have a lock so to speak on this cadence stuff). At face value, the graph seems to say that it's likely better to do less-than-moderate walking. Ditch all the exercise guidelines!

And by the time you get up to about 160 steps/min it's maybe worse than being completely sedentary.

I think this raises big red flags about the data and/or the methodology.

The authors wave their hands at limited data and resultant uncertainties to explain the reversal of walking benefits they find for step counts > 10K. This raises questions about the visualisations in the paper, at least, where the only indication of flakiness for higher step counts is the widening confidence interval.

But the cadence flakiness seems to me like a much more serious issue. I would be amazed if a really robust study failed to show clear benefits of 100+ steps/day over 75 steps/day.

Also, the top tercile in this stufy had peak 30 min cadence of 109 steps/min which seems just too low. I'm no athlete and I have a completely blocked femoral artery, but my 30 min peak these days is 130 steps/min and I average 125 steps/min for about 2 hours a day. Trotting around the parks, I get overtaken by too many other walkers, damn them ...

 

[Vonny]

Interestingly my calorie burning keeps pace with my steps per 10k, eg at 15k I burn 1700 calories, 16k 1800 kcals etc up to 20k. After that the calorie burn scarcely moves. So if I walk 30k, I still only burn 2200 calories! The majority of my steps fall into the cardio zone, so quite why it slows down after 20k is beyond me. The only control over extra calorie burn seems to be between 15 and 20k.
However, as I'm in France this week I'm bound to be in calorie deficit even if I walk 50k a day...too many temptations!

 

[Eddy Edson]

Interestingly my calorie burning keeps pace with my steps per 10k, eg at 15k I burn 1700 calories, 16k 1800 kcals etc up to 20k. After that the calorie burn scarcely moves. So if I walk 30k, I still only burn 2200 calories!

That seems pretty much in-line with the theory. Plugging values for you into my little walking spreadsheet ...

1. You probably burn about 1,300 - 1,400 kcal/day just mooching around:

RMR	970
Baseline Activity	1.4
=> Baseline kcal/day	1,358

(I used https://www.niddk.nih.gov/bwp to calculate yr Resting Metabolic Rate from yr age, sex, weight, height inferred from yr BMI. Baseline calories burned before any real exercise = 1.4 X RMR is a standard guesstimate. You'd set it higher if you were doing lots of regular housework etc.)

2. How much additional you burn from walking depends on how many steps and how fast:

Steps/min	100
Walk MET	3.0
=> Walk kcal/1000-s	28
=> Walk kcal/hour	170

If you walk at 100 steps/minute then you burn about 28 additional kcal per 1,000 steps, or about 170 additional kcal per hour. That adds on to the baseline activity burn calculated above.

(Details: "MET" = "metabolic equivalent of task" is a standard way of measuring energy burned from exertion, supposed to be indpendent of weight, age, sex etc. A MET of 2.0 indicates that you're buring energy at twice the rate of your RMR etc.

A standard reference for METs corresponding to differing walking cadences is the work of Tudor-Locke. Basically she comes up with a formula: 3 + (steps per minute - 100)/10. That means 3 MET for 100 steps/min, 4 MET for 110, 5 MET for 120, 6 MET for 130.

"MET-h" = "MET hours" = exercise MET times by the number of hours exercised. If eg you walk for 2 hours at a rate delivering a MET of 3.0 then the total 6.0 MET-h.

Knowing MET-h exercised and your baseline kcal/day you can then calculate amount of additional kcal from exercise: (MET-h / 24) * Baseline. And then the total kcal burned is Baseline + additional from exercise.)

3. Putting all that together:

kcal		Steps
		10000	15000	20000	25000	30000
Walking	​	283	424	566	707	849
Total	​	1,641	1,782	1,924	2,065	2,207

Total = Walking kcal plus constant Baseline kcal.

Assuming 100 steps/minute, theoretically you should burn a total of about 1,600 kcal if you walk 10K steps; 1,800 kcal for 15K steps; 2,200 kcal for 30,000 steps.

For every additional 5,000 steps you're increasing burn by about 140 kcal, but the percentage increase naturally declines.

So pretty close to what you report (which I guess might by unsurprising if you're using an app which employs the same kind of standard calcs?).

 

[Vonny]

This is really useful thanks @Eddy Edson, I don't use any apps or spreadsheets, just the info from my fitbit which has my weight plumbed in. This explains it very well thank you.

 

[Eddy Edson]

This is really useful thanks @Eddy Edson, I don't use any apps or spreadsheets, just the info from my fitbit which has my weight plumbed in. This explains it very well thank you.

I'm pretty sure fitbit uses the same kind of calculation - just because everybody seems to.

 

[Robin]

So all the people in the funeral procession for the Queen yesterday wouldn’t have got much benefit from their slow march.