New Study shows Shod running more efficient??

Oh I get what you are saying with that TJ, my issue with it is all in what the study is looking at. Its more efficient to run on roads than trails too, yet you don't see me trying to run on trails on a regular basis. I'm nearly certain its more efficient to run on asphalt than packed dirt but it hurts like hell so I'm not going to do it. Its more efficient to run on flat surfaces than hilly ones, yet people like running hills for the different muscle work. Regardless of the problems in the study, who knows it might be quite possible that running in shoes is a bit more efficient. However, if something is even 10% more efficient, but causes injuries is everyone going to go to the more to the more efficient thing? Well of course not, because the time you are going to spent injured and recovering completely cancels out the efficiency increase. So instead people will do the safe way to train and then put on shoes if its more efficient for the sake of races. I don't think a 3% decrease in efficiency is enough to cancel out the benefits that we all see. Its not that I don't care if people are putting out bad information about it, I just think they should focus on what is most important to most people first.
 
I took another look at the study, mainly to answer some questions folks were asking me...

ahcuah, I like reading your posts but but I'm still not following your reasoning re shorter stride length/higher turnover equating to higher energy usage/reduced "efficiency". A longer stride requires more energy per stride than a shorter one. Take one big step or two small steps, if you cover the same distance, you've burned virtually the exact same amount of calories (all other factors being equal).

I suspect that could also be demonstrated on a stationary, reclined bike. Lower the resistance but increase the turnover or raise the resistance and lower the turnover... the biker should cover a mile with the same calorie count in both cases.

A huge factor affecting this in runners though, would be experience. A shod runner taking off his shoes and doing the higher turnover/shorter stride thing would at first feel awkward and tense and thus waste more fuel than an experienced BF'er who can just relax and ejnoy the ride.

Likewise, if the test subjects here were given a good month or two to really get used to running under the test conditions, to the point where it was second nature to them, then the results could have been different. (By that I mean, have a runner run exclusively in the weighted half-shoe sock thing on a treadmill for a month, and then test his "efficiency". Then have him do the same with the Nike Mayfly, come back and test, and he'll probably have the same results. Do that with 100 runners to get a good sampling, and there ya go).
 
OK. Let me try to explain what I am thinking. I don't claim that it is necessarily correct.

First, let me say that I don't agree at all with relating this to any sort of bicycle. Bicycles are smooth (even if there is some non-constant effect from pedals going up and down and affecting power output); running has these abrupt transitions. To exaggerate: you jump into the air, you land and provide a bit of forward thrust to make up mostly for air resistance, and then you jump into the air again. I'm pretty sure most of the energy you use is in that jump. (Forward momentum means you don't need to supply much energy to keep moving, at least compared to getting off the ground and effecting a graceful landing.)

Suppose you run in place. In that case your O2/mile approaches infinity. As you slowly add forward motion (increasing stride length; keeping your cadence constant), your O2/mile comes down. So the stride length definitely affects how efficient you are. Yes, at some point that curve will turn around as you start straining for distance in the stride (and air resistance), but as long as you have not reached that point, a longer stride will be more efficient than a shorter stride.

Similarly, if you are trying to go a constant speed, if you shorten your stride, you are jumping up into the air more often (and again, I think this is where most of the energy is expended) and thus expending more energy.

Hope this helps. (Hope this doesn't sound too stupid.)
 
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Similarly, if you are trying to go a constant speed, if you shorten your stride, you are jumping up into the air more often...

...but not as far. Meaning, each stride is less strenuous. It seems very simple to me. Perhaps too simple.

Obviously the pace has to be constant when making any kind of comparison, otherwise you're comparing energy usage at, uh, different paces. Your idea of starting at 0min/mi doesn't make sense to me because as soon as you begin to move forward, you've upped the pace, so to speak,and thrown the numbers off.
 
...but not as far. Meaning, each stride is less strenuous. It seems very simple to me. Perhaps too simple.

I don't know how to explain it any better. If all of your energy is used in jumping into the air (as a gross simplification), what matters then is how often you jump into the air, not how far you jump. In that case, every stride is equally strenuous, so all that matters is how often you take a stride.

In real life, all of your energy isn't used, but the approximation is close enough that a 3% decrease in stride length could easily result in a 3% increase in energy used (particularly when operating in the middle of our normal range).

Do other folks understand what I am saying here? Or am I full of it?

I suppose I could produce a mathematical model and draw graphs, but that just seems like overkill.
 
I don't know how to explain it any better. If all of your energy is used in jumping into the air (as a gross simplification), what matters then is how often you jump into the air, not how far you jump. In that case, every stride is equally strenuous, so all that matters is how often you take a stride.

That really makes sense to you? Think about it some more... How can a stride of one meter be equally strenuous as a stride of half a meter? That's impossible (would be nice if it were true because we could all just run twice as fast with no extra effort).

Note: all of this stuff depends strictly on an even pace. That's the problem with your running-in-place analogy - you're going from 0min/mi to ann actual forward pace - can't really compare the two.
 
OK, let me try with a very simple model. I know it doesn't capture everything (by a long shot), but I hope it has the essentials.

Suppose your energy use depends on how often you "jump" and also how far you jump (stride length).

Let L = your step length (use step length so we count each jump)
Let F = the frequency of your jumps

Then your velocity V is L*F.

Your energy used is

E = A*F + B*L

where A and B are constants that measure the relative effort of jumping versus how far you go on each jump.

Can we agree that A is quite a bit larger than B?

Now, if we want a constant V and focus on the step length, then we have to rewrite that as

E = A*V/L + B*L

If you graph that, it has an asymptote at L=0, goes down to a minimum, and then slowly rises again (almost linearly).

Also, in the region we are talking about V is about 3 meter/sec and L is about 1 meter. So F is about 3 steps/sec.

If jumping uses 9 times the energy as striding, then we can use A=9 and B=1, and E=27/L + L. You can play with the numbers to see that we are in the downward sloping region, so that decreasing the step length really does increase the energy used.

That holds even if you choose A=3 and B=1, or even A=1 and B=1.

I hope this explains what I am trying to say. I don't think we run in that other part of the curve, just because I think jumping uses more energy than reaching a bit further on each jump. Obviously, eventually it makes a difference, but not here.
 
The way I've understood good running form is that vertical motion is bad which makes higher turnover superior at just about any pace in terms of efficiency. At any given frequency and ground contact time your vertical motion will be the same regardless of speed, right? I guess what I'm trying to say here, Ahcuah, is that I don't believe A is that much larger than B in your example. A and F should also be fixed and not change significantly from running in place to almost sprinting given reasonably good form. In fact, I have a feeling that most of the energy expended while running is used to propel you forward so B is likely much larger than A, at least I think so.

Apologies if this is incoherent or unclear, I'm about to head to bed so my mind isn't at it's sharpest at the moment. I'll gladly explain it all in the morning.
 
If you are trying to maintain a constant speed (as in the study) and L decreases, F has to increase, so it cannot be fixed. Conservation of momentum will mean that B is fairly small. While I use the word "jump" to refer to A, what it really encompasses is all of the energy expenditures that depend on frequency of steps, not stride length. Given that, I don't see how B can be larger than A, and it fact I suspect it has to be much smaller than A.

If anybody has data that says otherwise, I'd love to see it.
 
I actually do care. It's bad enough we have so much negativity surrounding our way of running, but then BS like this starts to propagate and makes us look like fools who have no clue. I am no fool, although the scars on my feet from running in shoes once made me one. Fool me once shame on you! Fool me twice, shame on me!

We don't need a bunch of bogus, bad info circulating around convincing people who would otherwise benefit from barefoot running. It's defeating, and if we don't voice our disagreement and point out the flaws of this study, then it's self-defeating.

Check out the story on the home page about this: http://thebarefootrunners.org/threads/debunking-the-university-of-colorado-barefoot-running-study-“unmaking”-the-case-for-running-shoes.6088/

TJ,

I agree that it's frustrating, and you are diligent in calling out those who are trying to distract and deceive the general public. It is important to fight back. But as you've said before, the best argument we can make is just to get out there and run barefoot ourselves -- that's the best way to promote it.

Have any of you noticed any changes in the rate or nature of comments you get when you run barefoot? I haven't -- still about the same on all fronts, as if these controversies in the media only reach a small fraction of runners and non-runners.
 
I agree, for casual runners and non-runners alike, these studies mean nothing and are probably seldom even read. I know I ran for several years without ever reading about running. I sometimes wonder why I read now.
The comments have remained the same for me too, something to the effect of how hardcore or courageous I am to be running barefoot. I always reply that it's a lot easier than it looks (if not necessarily more efficient :) ).
 
If you are trying to maintain a constant speed (as in the study) and L decreases, F has to increase, so it cannot be fixed. Conservation of momentum will mean that B is fairly small. While I use the word "jump" to refer to A, what it really encompasses is all of the energy expenditures that depend on frequency of steps, not stride length. Given that, I don't see how B can be larger than A, and it fact I suspect it has to be much smaller than A.

As you can probably tell, I just like thinking about and understanding this stuff. I agree with others that this research really doesn't have much to do with any average runners, though, either barefoot or shod. But I still find it fun.

Thinking about my model above, it obviously fails to capture anything like the true effect of lengthening stride. Clearly, at some point lengthening a stride has to asymptote out since it takes all of one's energy to leap that far. But I still think a similar model can be enlightening. Clearly, there is a part about efficiency related to step frequency (and I suspect the model captures that pretty well), and there is a part related to step length. I suspect the true curve looks more like this:

step.jpg


I also did some research of the literature and it does support what I say about shortening the stride is generally less efficient. In fact, it seems to be fairly well-known that experienced runners tend to choose the most efficient stride length based upon their individual physiologies. So varying off of that in any direction is less efficient. (Hey, that's some research that average runners might even be interested in!)

But note that that is experienced runners. If they are going barefoot and they are not experienced at that, they might then choose the less efficient stride length. If they are wearing yoga socks and have a fear of slipping, they might choose a stride length to address that, and again choose something less efficient.

I think this can explain the results of the Franz study as well as anything.
 
I also did some research of the literature and it does support what I say about shortening the stride is generally less efficient..

Still not buying the argument, lol. According to your information, we should actually by lengthening our strides and slowing our turnover rates but that is absolutely not good advice, honest! Regardless of the numbers you crunch, get out there and run with a loping 160-ish turnover rate, then work on getting that up into the 190 range and tell me how much worse you feel.

Consensus on the issue has been consistent for decades. Increasing turnover rate is one of the building blocks, the cornerstone even, of improving running form. Of course you can overdo it and become awkward and unnatural, but for the majority of runners trying to improve their form (with "efficiency" being one of the secondary benefits along with injury reduction) bumping that turnover rate into the 180-190 range is the easiest and most effective method available.

And for us barefooters, the magic number is 200. No kidding.

End of my statements on the subject, lol

:barefoot:
 
Willie, while I agree partially I also will say not everyone is the same. For me, running any higher than 180 and I get tired super fast and feel like I am straining really hard. Same can be said when I run below 170. For me being in between these zones is my own personal comfort zone. When I run faster my stride does actually elongate as well, just not out in front of me but more behind me, although my cadence does stay right in the same range. When I go slow up a hill my cadence is the same but my strides are incredibly short. I can't maintain a 200 cadence, probably couldn't even make it the mile down the hill from my house at that rate. Drop my cadence to 180 and I am golden for hours though.
 
I can't keep a 180 or above either, Nick. I suck. That's just me though. Doesn't mean I can't run comfortably below that cadence, barefoot or shod though.
 
Please ignore what I said about Ahcuah's math being off earlier. I was tired and not thinking straight, it happens from time to time. :rolleyes:
 
I can't maintain a 200 cadence, probably couldn't even make it the mile down the hill from my house at that rate..

Nick - You might simply be running faster when you bump up the turnover rate, which obviously means you wear out quicker. Have you ever tried running with a metronome? It's a good training tool.
 
I also did some research of the literature and it does support what I say about shortening the stride is generally less efficient. In fact, it seems to be fairly well-known that experienced runners tend to choose the most efficient stride length based upon their individual physiologies.

Aren't these two sentences contradictory ? If I'm chosing the most efficient stride length for me, doesn't shorter vs longer become moot ?

Isn't the question simply, what is the optimal stride length at a given velocity, factoring in the physiology of the runner ? To me it's not about whether longer or shorter strides are more or less efficient, as neither is true in their extremes. You're trying to propel yourself forward as efficiently as possible (least wasted energy) so minimizing upward movement (required for longer strides) and minimizing drag (efficiency of transition) seem to me the key ingredients. Any breaking during foot transition, or unneeded vertical motion is energy lost in forward propulsion that needs to be made up for by the runner. If my cadence remains constant, and my stride simply shortens or lengthens, that seems to me to be most efficient. However, that optimal cadence is tied to my physiology (factors including leg length). My understanding was that higher cadences (generally) create a more efficient foot transition (less breaking, less foot time on the ground)....
 

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