Sunday, August 21, 2011

Is 10k steps a day really a magic health bullet? Catrine Tudor-Locke suggests this may be the wrong question.

We hear a lot about the value of getting ten thousand steps a day. Pedometers are being sold increasingly as a way to track progress towards that magic 10k. But is there any basis in this assertion of ten thousand steps that something wonderful happens at 10k that doesn't anywhere before (or after)? And are all such steps in that 10k created equal? Are all or any of these steps the same as NEPAs or  non-exercise physical activity (overview here at nopain2.org)- the movement carried out over the course of a day that is outside deliberate exercise activity, but that seems to have significant value in helping one get and stay lean?

ResearchBlogging.orgIn July 2011 a trio of journal articles lead by  long time step/health researcher Catrine Tudor-Locke  have come out looking at the step question, literally “how many steps are enough”  - one geared at kids, the other at adults and another at elders and special populations (citations below). In this post we’re going to look over the work on steps for adults. As with just about everything, the answer to the question “is it 10k??” is “it depends.” And that perhaps more interestingly, there seems to be a gradient of effect for things like weight loss, after which more is not more.

So let’s begin with  a few terms. NEPA we’ve already met. The other is MVPA - moderate to vigerous physical activity. Both are ways of describing level of effort and are important measures when talking about the effectiveness of stepping out.

There’s a kind of interesting component to trying to figure out “how many steps is enough?” - the question might be “what is someone trying to achieve”?

How to figure out Steps
CORRELATION? So we can consider what do most people who are healthy do - measure these steps and extrapolate out from that to try to determine a correlation. Indeed this is what various mortality studies have done in various parts of the world: look at the self reports of people’s activities, compare that mortality rates and say heck folks who have these many NEPAs seem to live X% longer with Y% less incidence of these types of disease. Maybe that’s because of the walking or related effort.

DELIBERATE EFFECT? Other types of measures are to do deliberate tests: we’ll monitor how much these folks walk and eat, and we’ll ask group A to walk X steps a day and the other group, we won’t encourage to walk. At the end of a given period we’ll check a bunch of measures from blood to weight to body fat and see what difference anything made.

SELF-REPORTING VS MEASURING? One of the strategies here is also to consider different ways of measuring NEPAs or steps. Recently there has been more literature where participants have pedometers but the large-scale studies described above are based on self-reports of times and distances of various activities and estimates around these. Also, not all pedometers measure steps in quite the same ways. So there’s some fuzz in the data. Science isn’t always an exact science.

TRANSLATION? Another fuzzy strategy is to try to translate one type of activity for another. If for instance 30 mins a day of MVPA is seen as an important measure of health, into  how many steps (and at what speed) does that translate activity translate?

EQUATION?  if daily MVPA is supposed to be over and above the NEPAs, what’s the amount of NEPAs and how translate that to steps? Total steps potentially becomes two different kinds of step: NEPA + MVPA = total. 

The authors of the How Many Steps studies considered each of these components to make the best case they could for their recommendations.



Normative Data - just checking
For adults under 65, an intense review of internationally published paper came to an average of 9,448 steps/day. This surprised me. When the data is restricted to the US, the average is 5600 steps/day. That seems more familiar based on what we see of geek steps in our lab. For context, Japanese are at 7200 and Western Austrailians 9600. Ineresting, no? What information i do NOT have is how these step numbers correlate to other health markers: the studies just considered daily activity steps. Alas. But it does give us a pretty good sense of practice differences internationally.

Grading the Normative Data
The authors of the current study have been interested in steps for some time. Over the course of 2004 − 2005 they have developed and tuned a scale for understanding step ranges and have proposed

  • 1) less than 5,000 steps/day (‘sedentary’); with less than 2,500 steps/day (‘basal activity’) and 2,500-4,999 steps/day (‘limited activity’)
  • 2) 5,000-7,499 steps/day (‘low active’);
  • 3) 7,500-9,999 steps/day (‘somewhat active’);
  • 4) >10,000-12,499 steps/day (‘active’); and
  • 5) ≥12,500 steps/day (‘highly active’). 
This means, as the authors point out, the US is overall “low active”

Why bother with these Steps? Such graduation can help understanding the effects of particular interventions: if 5000 steps a day has X% incidence of cardiovascular risk, but “somewhat active” means that incidence level goes down by a factor of 10, but that between somewhat active and active there’s only a tiny difference in cardiac incidence, then one’s focus may be to get folks just to somewhat active rather than pushing to active. Indeed, 2500 steps a day improvement does seem to show modest weight loss benefit but real blood pressure improvements.

Moderate Intensity Walking - Where MVPA begins
From the controlled experiments apparently one of the attributes confirmed is that if one is hitting 100steps a minute, one is at a suitable cadence to hit the MVPA. There’s an extension peeping up here: 3000steps within 30mins is looking good for the MVPA part of the total step equation. Doing this stepping in ten minute blocks is also ok.

A great way i’ve been noticing to get up my cadence without effort is to practice barefoot walking as described in part IV of the recent discussion about barefoot running: stride changes to soften any heel striking and move more to the mid/forefoot.

Total Counts: is it 10k?
Another extension of the above gradation of walking values is a good daily step target: 3k at MVPA + the high end of “sedentary” 5K steps = a total of 8k.
that assumes a 30min/day activity level; some guidance is apparently 60mins. So we have a range of 3-6K in MVPA (100steps/min) + 5k = 8-11k steps a day, assuming the MVPA components.

As a side note, the authors show that in studies that have attached accelerometers and pedometers to people have shown that getting the right amount of MVPA seems to correlate with folks getting 7000-8000 steps a day. (accelerometers by the way are like the sensors on some smart phones that let them play light saber - detecting how fast and in what direction something is moving)  In other words, as the authors note, the original framing that set “10k” steps as “active” people, may actually start as low as at 7k a day when MVPA is added in. We are getting another validation of the 8-11k heuristic proposed for MVPA + NEPA (or “free living activity” as the authors call it).

WHY STEPS?
As the authors note, people do way more things than just walk. So why care about steps so much? The authors suggest “bipedal locomotion” as a thought. We fundamentally get around and move around by walking. Walking is also apparently the most frequently reported leisure activity.

Connection with Weight Loss

Here’s some related work that the authors note in studies around stepping patterns and BMI (body mass index). Let me quote the passage:
Krumm et al. [29] examined the relationship between pedometer-determined steps/day and body composition variables in 93 post-menopausal women. In relation to BMI, a linear relationship was observed such that women who took 5,000-7,500 steps/day had a significantly lower BMI than those who took < 5,000 steps/day. Further, women who took 7,500-9,999 steps/day had a significantly lower BMI than those who took 5,000-7,500 steps/day. There was no significant difference in BMI between women who took 7,500 -9,999 steps/day and those who took greater than 10,000 steps/day.
SO this result is pretty important: BMI is a standard measure of bodyfat associated with height and weight . There are some folks who argue reasonably that there are limitations with BMI: that someone who is really in shape packing considerable relative to body fat will show up as having a higher BMI than an average person at that height and weight. Yes, this is true. But given that, that usually indicates that person is likely also pretty healthy/active and will be using other measures than BMI to assess their health, fitness and bf%. So for more average folks (the majority of us), BMI is not a bad marker of how well one is doing in terms of weight.
What that metric about steps to bmi tells us is that there are two important ranges where one can achieve *signficant* benefit: the first area is 5000-7000 is a HUGE difference than 5k and below: women have statistically significantly lower BMIs - changes in whole bmi numbers are associated with real pounds of weight loss.To think that there is yet ANOTHER significant difference from that first group to the 7500-9999 thousand steppers is golden.

For gals then thinking about wanting to change our BMI, stepping up a level is important. Just as critically though is that there is NOT seen to be a greater benefit to bmi after hitting the 10k mark. More is not always more for everything.

Again, the 8-11k a day is sounding very beneficial for correlations with blood pressure, bmi and general health.

Enough or Too Few?
Indeed, the authors consider reframing the question of how many steps do we need, to how many steps is too few? For example, fewer than 5k steps has greater risk of  particular cardiovascular incidents.

Likewise encouraging folks who wish to see blood pressure or weight changes may be directed to seek particular increments rather than just going for a total. And similarly, it’s possible to get that 10k value without getting the 3k that seem necessary for MVPA work.


MAKING IT REAL: FitBit (and Zeo)
I’ve been focusing a lot over the past several months now on my non-excercise physical activity - how many steps do i get total; what percentage of them is MVPA vs NEPA and how do these simple totals connect with my lean down goals for right now. TO monitor this rather than kid myself with well i think i moved a lot today,  i’ve gotten a FitBit. In fact we have a bunch in our lab.

The idea with the fitbit is that it’s both a step counter in the pedometer sense and an accelerometer - so it takes into account movement that a pedometer would not track - it can assess if you’re running or going up stairs or walking. It also calculates calories burned and distance travelled, and if you have its usb antenna plugged into a computer, it will wirelessly upload the fitbit data. Oh, and it also monitors sleep - sort of - but i much prefer zeo for this (zeo discussed here and here). 

OPEN data - an aside note: zeo and fitbit both let people keep their own data. this may sound odd but try doing that with body bug - another self monitoring tool. This open data approach means that other applications can be built (like run keeper) that integrate the data from both zee and fitbit to make it easy to see how various parts of one’s performance are affecting the other.

Preliminary Conclusions with FitBit - one of the cool things about the fitbit is that if i check it and i see where i’m at - if it’s on the low side, i start to make plans for where i can get more steps in during the day and after work. If i have a workout planned for that day, i may let myself off the hook a bit. Now knowing about mvpa i can do that.

I got asked recently if FitBit counts kettlebell movements - it’s great for swings - but i’ve actually NOT been wearing it during workouts - i want to focus on movement OUTSIDE my workouts. When i’m walking and not just moving about the office for instant at work, my walking pace already is generally over the 100 steps/min -  so i can usually be assured i’m getting in that 3k minimum of MVPA - but i don’t have to trust myself - the FitBit provides a chart of exactly when my steps were taken and how many in any given block; it also estimates activity level within these blocks.

Results: i have been deliberately trying to lean out over the past few months - something i'll write about in the near future. The main thing contributing to that leaning out is food: eating strategies, combining precision nutrition food approaches with as Brad Pilon puts it occasionally stopping eating for 18-24 hours in a week. Recently this once a week fast is something John Berardi of Precision Nutrition has been trying, too while minimizing workouts as an experiment. So let's just put that one on the table as it were: what i eat or don't eat is plainly the biggest contributor to my fat carving progress.

So where do the steps come in?
I really cannot say if my progress towards lean is better for getting in 8 or more k of steps per day. I know that i was motivated to check this out when a recent t-nation article by Lonnie Lowery suggested that when someone hits a wall with lowering their caloric intake to about as low as it can safely go, the only other place left to help the fat burn along is to raise caloric burn levels, and that he noticed something that makes a difference is what happens if NEPAs start to drop below 7k a day (see the NEPA factor in this article). Ah ha, thought I.

Recall above that there are two zones of steps - both under 10k but above 5k that have best effect on BMI - why, they haven't said, but perhaps there's something special getting tweaked from that kind of activity that has a metabolic switch to it. Ok. I'll go for that.

Beyond possible contribution to fat burning, I tend to feel better generally in terms of movement; i know that if i get the steps in throughout the day rather than just end of the day i feel fresher. So i’d add that in- frequency of movement throughout the day -  as a variable beyond total steps, amount in MVPA, in figuring out quality of steps.


Conclusions:
To answer the question we started with, ten k a day is certainly a fine number for steps, but what Tudor-Locke's and Colleagues research and literature review shows us is that, more particularly, there are ranges of values and qualities within those ranges that will help yield the effects we may desire for health and wellbeing.
  • There is a way to think of steps in terms of gradations from sedentary to active
  • within these gradations are associated particular health benefits - after which these particular benefits no longer seem to accrue. That's not to say one shouldn't walk more that this level; just that the benefits for certain markers seem to tail off from that activity alone.
  • An effective target seems to be 3-6k steps in the MVPA range and another 5k in "free living activity" steps (what we might also think of as NEPAs).
  • A fitbit makes it very easy to see whether one is getting that range daily and whether one is getting that minimal MVPA 3k portion in particular. Keeping a record is a great way to measure and validate progress.
Take Home: when stepping out and up, rather than shoot for 10k right off the bat, we may want to think about milestones: first to get from basal 2500 to 5000, focusing on upping the 1000k blocks in the MVPA range. Then, for more health benefit, to get above those sedentary 5k a day towards 8000, with three k in the MVPA zone, and from there, if we wish to do the best we can with our walking health benefits, to 11k  going from 3k-6k in the MVPA zone.



Citations
Tudor-Locke C, Craig CL, Aoyagi Y, Bell RC, Croteau KA, De Bourdeaudhuij I, Ewald B, Gardner AW, Hatano Y, Lutes LD, Matsudo SM, Ramirez-Marrero FA, Rogers LQ, Rowe DA, Schmidt MD, Tully MA, & Blair SN (2011). How many steps/day are enough? For older adults and special populations. The international journal of behavioral nutrition and physical activity, 8 (1) PMID: 21798044

Tudor-Locke C, Craig CL, Aoyagi Y, Bell RC, Croteau KA, De Bourdeaudhuij I, Ewald B, Gardner AW, Hatano Y, Lutes LD, Matsudo SM, Ramirez-Marrero FA, Rogers LQ, Rowe DA, Schmidt MD, Tully MA, & Blair SN (2011). How many steps/day are enough? For older adults and special populations. The international journal of behavioral nutrition and physical activity, 8 (1) PMID: 21798044

Tudor-Locke C, Craig CL, Beets MW, Belton S, Cardon GM, Duncan S, Hatano Y, Lubans DR, Olds TS, Raustorp A, Rowe DA, Spence JC, Tanaka S, & Blair SN (2011). How Many Steps/day are Enough? For Children and Adolescents. The international journal of behavioral nutrition and physical activity, 8 (1) PMID: 21798014

4 comments:

Kyle said...

The way I see it, 10,000 steps may or may not be a magic number, it doesn't matter. But someone who is currently doing 2,000 steps and who builds them up - to whatever number - is generally going to be fitter and less likely to be obese than someone who keeps them under 2,000 steps.

I say this to new gym members who are obese and want weight loss, or who are just very unfit,

"Wear it for a week, and just do whatever you normally do. If you're doing 2,000 steps a day, okay, over the next several weeks build it up to 10,000 and then see where you are. If you're doing 12,000 steps a day, well then obviously we need more extreme measures!"

What I've seen is that a person may be underweight or overweight and do 10,000 steps a day; but they won't be obese. Either the extra steps drops some weight, or the extra weight makes the extra steps too hard and they give up.

I have seen that someone who was doing <2,000 and builds it up to around 10,000 sees many benefits. If they get benefits from going to 20,000 or so I don't really see it. Going from doing "bugger all" to doing "some stuff" helps a lot; going from "some stuff" to "a lot of stuff" doesn't seem to carry the same level of benefits.

But really you have to look at each individual. Like I said, if someone is doing very little, they can build up to doing something and then see where they are.

I couldn't guess the exact level of that "something." But if we're in the mindset of "what is the minimum to get me benefits?" well that person is unlikely to actually do that minimum. Doesn't mean we all have to be Olympic-level ambitious, but...

"How many steps do I need to do?"
"More."

mc said...

Kyle,
thanks for stopping by. It's interesting that you say "the way i see it"...

Since if you read this post, you'll see that your comments / experiences pretty much echo what the post and the research articles note: more is better than none.

As you've seen and as apparently the researchers have seen too: moving from basal (2k) to more is better.

And while you suggest that you "couldn't guess" what that exact something in the steps is, the research seems to take a grounded stab at it by correlating what changes do occur at different gradations of steps.

Have you really had people taking 20k steps a day? goodness.

What seems interesting tho, especially with your focus on the individual, is that the answer does not seem to be what you conclude finally to "how many steps" - it's not always going to be "more" - fortunately. And that's rather soothing too, don't you think?

thanks again for dropping by,

best
mc

Kyle said...

Yes, I've had people doing an average of 20,000 steps a day. That's an average, so obviously there were slower and faster days.

I've one client now who's walking 7km to and from work 3 days a week - so that's basically 60,000 steps over the 3 days even if she sits down the rest of the time.

If the person is asking "how many steps?" then the answer is always "more." It's like when people ask if they have a strong deadlift or whatever. If you have to ask, you need some more work.

mc said...

Well kyle that's great. Your clients who walk three days a week may be interested in work that shows that if we do sit down for the rest of the time, our goose may still be cooked: it seems we need movement throughout the day to manage insulin and other markers - that the one hour blast in the gym (or likely walking ) a few times a week doesn't offset this.

I've also recently become very hesitant to say "more" as a default in any context. Many folks do not know how to balance their work effort with the need for recovery - whether this is working at the office or working out; it can also be debilitating to feel like what one is doing is never enough.

That's why i'm glad to see that there is a ceiling on particular benefits from say walking - and these seem to be at the 11k zone. Not that more is bad, it's just not going to be more for weight loss or blood pressure or or or...

so perhaps, if someone is looking for more, it might be time to consider "other" rather than more. or better - like more frequent bouts rather than all at once, etc.

thanks for coming back.
best with your practice.

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