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2012-10-07 10:06 AM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
When I started running about five years ago, I put this question to a couple that I know. Both are civil engineers, with multiple Masters degrees and a PhD in the field, between them. Both are BQers, and he is a nationally ranked masters runner and coach. They know waaaaaaaaaayyy more about engineering and running that I will ever care to know. Their advice to me was that concrete is harder and less forgiving than asphalt, and to avoid concrete as much as possible.

I took their advice, and avoid sidewalks unless its unsafe to do so.


2012-10-07 10:37 AM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
alath - 2012-10-06 9:31 PM

gsmacleod - 2012-10-06 8:04 PM
ascottweiland - 2012-10-06 7:07 PM I know I'm way late in talking on this subject.  Just signed up.  Anyway, here's the skinny on asphalt vs. concrete. Concrete = 150.01 psf  Asphalt = 140 psf  That's a 7% difference.  Since we take over 30,000 foot strikes in a marathon..... It makes a difference.
Funny that the study posted just above your post found that there was no difference. While your argument seems reasonable and would be what most people woudl give as a common sense response, the available data do not support your hypothesis. Shane

Well, to be precise, the study found no difference on the variables they investigated. What the results of the study mean depends on whether you believe those variables are the best indicators of the outcomes we care about. Until they find a reliable way of measuring Total Global Runner Happiness Factor, we will be stuck looking at a lot of different variables and wondering how well they represent what we care about.

Going the other way, it's perfectly possible that a measurable 7% difference in surface hardness is not enough difference to influence Total Global Runner Happiness (or its associated variables investigated in the linked study).

See, this is the cool thing about research - we're always getting new bits and pieces of data, without ever definitively answering the question.

That's not what he posted... he posted difference in DENSITY... which may or may not determine hardness. Lead is more dense than steel, but it certainly is not harder.

I run dirt mostly, and find no real difference between concrete and asphalt.. While anyone can look at a worn asphalt road and know it is softer than concrete.... that is meaningless between the difference in soft tissue and asphalt. To us, asphalt is quite hard indeed and the deflection we may or may not induce in it with a foot strike is negligible compared to concrete. Especially when you factor in EVA new and worn, and soft tissue... young and old.

2012-10-07 1:17 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?

FWIW, I started this thread 2.5 years ago as I was moving from a place where I ran almost 100% on asphalt to one where I would run mainly on concrete.

I don't think the change from asphalt to concrete made any difference to me in the last 2+ years.  Any injuries I had were from running on a nice, rubber, HS track, but running too fast.  I don't think that concrete running contributed.  My training volume has gone down a good bit, but I had my best Oly run this year.

Brian

 

2012-10-07 1:20 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?

dexter - 2010-04-27 12:03 PM GO put to the side walk and hit with a hammer then try doing the same on the asphalt.  You tell me which is softer. 
In hardness testing off the top of my head asphalt 6/10, concrete 9-10/10.  That is for running surfaces not minerals
Training as you race run on asphalt.

Then hit the bottom of your shoes with the hammer and tell us which of the three is softest.  It will be the shoes by a huge, huge margin. 

The fallacy in thinking here (and it seems almost universal in this thread) is that the hardness difference between those two will matter.  It won't - particularly when you are wearing shoes designed with cushioning orders of magnitude softer.  The give will be 99.9+% in your shoes and muscles. 

Now, having said that I do prefer to run on asphalt as it is so much smoother in most cases.  That is where the difference many people note likely comes from.

2012-10-07 1:47 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
I like asphalt, bricks (the kind they build roads with) or cobblestones are the absolute worst.
2012-10-07 2:21 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
this thread is like arguing about whether 250 pound man is going to benefit from a bike that is one pound lighter.

asphalt is softer, yes. but seriously think about it. density of the material doesn't determine how hard the material is, or even how much "give" it has. so that argument is toast.

now for the math. each of my shoes are an approximate sole surface area of 33 square inches. i weigh 180 pounds. now, know that in proper running form you should land flat-footed that means they my surface impact is only about about 5.5 pounds per square inch. this is not accounting for my downward acceleration due to gravity, the loss for my forward acceleration and give from my knee, but those to should cancel each other out rather well, making any loss or gain from either negligible. lets just say 6 pounds per square inch. now go take a 1" square piece of rubber of the same material as your shoes and press down on it against the concrete using 6 pounds of force. do the same to asphalt. if you can see the difference i'm throughly impressed. the difference is going to be negligible, even amplified by how ever many strides you may make in your run.

unless you weigh 1000 pounds and have pegged legs it does not matter.



2012-10-07 5:05 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
ascottweiland - 2012-10-07 12:07 AM

I know I'm way late in talking on this subject.  Just signed up.  Anyway, here's the skinny on asphalt vs. concrete. Concrete = 150.01 psf  Asphalt = 140 psf  That's a 7% difference.  Since we take over 30,000 foot strikes in a marathon..... It makes a difference.  http://www.aqua-calc.com/page/density-table

You're confusing density with hardness. There's no simple (if any) correlation between the two.

BR

2012-10-07 5:09 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
sand101 - 2012-10-07 1:20 PM

dexter - 2010-04-27 12:03 PM GO put to the side walk and hit with a hammer then try doing the same on the asphalt.  You tell me which is softer. 
In hardness testing off the top of my head asphalt 6/10, concrete 9-10/10.  That is for running surfaces not minerals
Training as you race run on asphalt.

Then hit the bottom of your shoes with the hammer and tell us which of the three is softest.  It will be the shoes by a huge, huge margin. 

The fallacy in thinking here (and it seems almost universal in this thread) is that the hardness difference between those two will matter.  It won't - particularly when you are wearing shoes designed with cushioning orders of magnitude softer.  The give will be 99.9+% in your shoes and muscles. 

Now, having said that I do prefer to run on asphalt as it is so much smoother in most cases.  That is where the difference many people note likely comes from.

I'm wondering how much this plays in as well. Concrete sections on the sidewalk are more likely to vary in height, angle, etc,  from one to the next, making it that little bit trickier to judge when the impact comes. Another poster brought up the difficulties of brick & cobblestone roads.

2012-10-07 5:32 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?

I would bet that the quality of cushioning in your shoes and the conditioning of the tissue in your feet are far more important than the density of the surface you repeatedly slam that cushioning into.

I vastly prefer running on trails when I can, but most of my runs happen before the sun comes up. I have a mild personal preference for asphalt over concrete, but my dog does not like being on the asphalt when there is a concrete sidewalk available. 

2012-10-07 6:26 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
mrheathen - 2012-10-07 5:32 PM

I would bet that the quality of cushioning in your shoes and the conditioning of the tissue in your feet are far more important than the density of the surface you repeatedly slam that cushioning into.

I vastly prefer running on trails when I can, but most of my runs happen before the sun comes up. I have a mild personal preference for asphalt over concrete, but my dog does not like being on the asphalt when there is a concrete sidewalk available. 

Funny, I figured you for a brimstone kind of guy.

2012-10-08 9:24 AM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
Yes, it makes a difference. I can tell a difference in the "sound" of my footstrikes between the two. If you were to blind fold and make me run 25 yards, I could tell you what I was on in 5 steps.  I have pains after concrete that I don't have after other surfaces over same distance. Concrete is hard. I especially notice this in summer when asphalt heats up, it softens- I much prefer it.  Scientific literature to support this? I've not done any research.


2012-10-08 10:21 AM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
nolken - 2012-10-07 1:21 PM
now for the math. each of my shoes are an approximate sole surface area of 33 square inches. i weigh 180 pounds. now, know that in proper running form you should land flat-footed that means they my surface impact is only about about 5.5 pounds per square inch. this is not accounting for my downward acceleration due to gravity, the loss for my forward acceleration and give from my knee, but those to should cancel each other out rather well, making any loss or gain from either negligible. lets just say 6 pounds per square inch. now go take a 1" square piece of rubber of the same material as your shoes and press down on it against the concrete using 6 pounds of force. do the same to asphalt. if you can see the difference i'm throughly impressed. the difference is going to be negligible, even amplified by how ever many strides you may make in your run.


I see very little "math" here. Assuming the 33 sq-in surface area of your shoe is correct (I'm not looking it up), you have correctly calculated PSI for you standing in place. The rest is just speculation.
2012-10-08 10:33 AM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
RockTractor - 2012-10-08 10:21 AM

nolken - 2012-10-07 1:21 PM
now for the math. each of my shoes are an approximate sole surface area of 33 square inches. i weigh 180 pounds. now, know that in proper running form you should land flat-footed that means they my surface impact is only about about 5.5 pounds per square inch. this is not accounting for my downward acceleration due to gravity, the loss for my forward acceleration and give from my knee, but those to should cancel each other out rather well, making any loss or gain from either negligible. lets just say 6 pounds per square inch. now go take a 1" square piece of rubber of the same material as your shoes and press down on it against the concrete using 6 pounds of force. do the same to asphalt. if you can see the difference i'm throughly impressed. the difference is going to be negligible, even amplified by how ever many strides you may make in your run.


I see very little "math" here.

ha yeah when i wrote "now for the math" i was originally going to calculate impact values and such then i realized it wasn't worth my time so i just left those variables out, as they would be unimportant for the sake of argument anyways.

RockTractor - 2012-10-08 10:21 AM
Assuming the 33 sq-in surface area of your shoe is correct (I'm not looking it up), you have correctly calculated PSI for you standing in place. The rest is just speculation.


the vast majority of science is speculation. there would be no argument here if one was to not speculate. really the only variable that i see making a huge difference is the runner's form

Edited by nolken 2012-10-08 10:33 AM
2012-10-08 10:50 AM
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Subject: RE: Asphalt vs Concrete: Does it really matter?

I build roads, both concrete and asphalt.  I design them for 80,000 lb trucks, not 200 lb people.  I agree asphalt is softer.  Concrete is considered a rigid pavement, and asphalt is considered flexible.  Even a passenger car has little affect on a road surface.  Trucks are what deflect the road.  I'm not sure if this even correlates into how the road shock feels to a runner. 

Heat also affects asphalt more.  Asphalt flows much more when temps are high.  Motorcycle kick stands can even sink into asphalt on a hot day.  On a cool night, you won't see that issue.Asphalt itself is a petroleum product, similar to tar.  It is flexible and flows like a plastic.  For an example, there is usually a bump where asphalt meets concrete pavement.  This is due to asphalt flowing towards the concrete.

Another issue is traction.  Concrete is smoother.  Asphalt typically has a rougher surface, especially if it is a chip-seal surface.  Trails have loose gravel or dirt, which reduces traction even more.  I would be interested to see if traction makes a difference on stride length, etc.

A few corrections - roads have camber, but so do sidewalks.  Typical designs for roads and sidewalks have the same cross slope (2% on average).  This varies, but sidewalk tend to slope towards the curb in order for water to drain.  Also, not all asphalt has rubber in it.  Some asphalts have crumb rubber from old tires, but that is relatively new. 

I have no evidence, but I prefer running on crusher fine (really small crushed rock, almost dust) trails, then roads, then sidewalks.  My dog prefers dirt, concrete, then asphalt.  I think the 170 degree temps that roads can get to and the rougher surface texture have to do with that.



Edited by ktsdad 2012-10-08 10:51 AM
2012-10-08 12:14 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?

Concrete is cement, water and aggregate making a solid object.

Asphalt is binder and aggregate that is temperature sensitive.  The hotter it is the softer the road.  Different binders are used in the north and south.

If new to running take a few weeks before doing sprints on Concrete. 

If I remember correctly the concrete has a higher frequency of causing shin splints when starting.

If you increase by 10% a week it shouldn't matter.

2012-10-08 2:04 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
edscoville - 2012-10-08 12:14 PM

Concrete is cement, water and aggregate making a solid object.

Asphalt is binder and aggregate that is temperature sensitive.  The hotter it is the softer the road.  Different binders are used in the north and south.

If new to running take a few weeks before doing sprints on Concrete. 

If I remember correctly the concrete has a higher frequency of causing shin splints when starting.

If you increase by 10% a week it shouldn't matter.

my what a fine collection of facts and opinions that are not correlated!  I'm a civil engineer, and you probably can tell the difference about which you're running on... just like you can probably tell the difference running on different types of grass. or grass vs a dirt trail. This doesn't mean one will be more likely to cause injury.  As far as actual deformation of the surface goes; lets say you are running at a 180 foot strikes per minute cadence.  If a foot was on the ground constantly (which it isn't, you are in the air with no feet on the ground while you are running, but we can ignore that for now) each foot strike would be 1/3 of a second (60/180 = 1/3).  How much do you really think you can compress a surface with a modulus of elasticity of at least 2 MPa in .333 seconds (actually far less) with your measly 150-250 lb body?  No discernable amount by the standards of your body's ability to feel.  On top of that, the compression of your shoes is probably significantly more, and varies more step to step than the actual compression of the asphalt surface.

its all in your heads guys.



2012-10-08 2:34 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
dmiller5 - 2012-10-08 1:04 PM
my what a fine collection of facts and opinions that are not correlated!  I'm a civil engineer, and you probably can tell the difference about which you're running on... just like you can probably tell the difference running on different types of grass. or grass vs a dirt trail. This doesn't mean one will be more likely to cause injury.  As far as actual deformation of the surface goes; lets say you are running at a 180 foot strikes per minute cadence.  If a foot was on the ground constantly (which it isn't, you are in the air with no feet on the ground while you are running, but we can ignore that for now) each foot strike would be 1/3 of a second (60/180 = 1/3).  How much do you really think you can compress a surface with a modulus of elasticity of at least 2 MPa in .333 seconds (actually far less) with your measly 150-250 lb body?  No discernable amount by the standards of your body's ability to feel.  On top of that, the compression of your shoes is probably significantly more, and varies more step to step than the actual compression of the asphalt surface.

its all in your heads guys.



So.... which is it?
2012-10-08 2:40 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
RockTractor - 2012-10-08 2:34 PM
dmiller5 - 2012-10-08 1:04 PM my what a fine collection of facts and opinions that are not correlated!  I'm a civil engineer, and you probably can tell the difference about which you're running on... just like you can probably tell the difference running on different types of grass. or grass vs a dirt trail. This doesn't mean one will be more likely to cause injury.  As far as actual deformation of the surface goes; lets say you are running at a 180 foot strikes per minute cadence.  If a foot was on the ground constantly (which it isn't, you are in the air with no feet on the ground while you are running, but we can ignore that for now) each foot strike would be 1/3 of a second (60/180 = 1/3).  How much do you really think you can compress a surface with a modulus of elasticity of at least 2 MPa in .333 seconds (actually far less) with your measly 150-250 lb body?  No discernable amount by the standards of your body's ability to feel.  On top of that, the compression of your shoes is probably significantly more, and varies more step to step than the actual compression of the asphalt surface.

its all in your heads guys.

So.... which is it?

both.  you can tell the difference in surfaces based on lots of things, like texture for instance.  that doesn't mean you can feel how much you are compressing the surface

2012-10-08 3:00 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
dmiller5 - 2012-10-08 3:40 PM
RockTractor - 2012-10-08 2:34 PM
dmiller5 - 2012-10-08 1:04 PM my what a fine collection of facts and opinions that are not correlated!  I'm a civil engineer, and you probably can tell the difference about which you're running on... just like you can probably tell the difference running on different types of grass. or grass vs a dirt trail. This doesn't mean one will be more likely to cause injury.  As far as actual deformation of the surface goes; lets say you are running at a 180 foot strikes per minute cadence.  If a foot was on the ground constantly (which it isn't, you are in the air with no feet on the ground while you are running, but we can ignore that for now) each foot strike would be 1/3 of a second (60/180 = 1/3).  How much do you really think you can compress a surface with a modulus of elasticity of at least 2 MPa in .333 seconds (actually far less) with your measly 150-250 lb body?  No discernable amount by the standards of your body's ability to feel.  On top of that, the compression of your shoes is probably significantly more, and varies more step to step than the actual compression of the asphalt surface.

its all in your heads guys.

So.... which is it?

both.  you can tell the difference in surfaces based on lots of things, like texture for instance.  that doesn't mean you can feel how much you are compressing the surface

its not about compressing the surface...its about the damping coefficient and stiffness modulus. those two material/structural constants have a big role in determining the resultant forces of the impact between your shoe and the running surface.  just because the surface doesn't deform from each foot strike doesn't mean one surface isn't better at damping the force of impact and lowering the resultant forces on your joints.

2012-10-08 3:01 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?

It's not how much our bodies are compressing the surface, whether it is asphalt, concrete, or dirt....it's how much impact is transmitted to our bones, joints and soft tissues.

While in that study, there may not have been a demonstrable difference in injury rate, that didn't address whether running on a softer surface is more comfortable for a runner.

I'll chose trails or asphalt over concrete any day, when I have the choice.

2012-10-08 3:10 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
bets12 - 2012-10-08 2:01 PM
I'll chose trails or asphalt over concrete any day, when I have the choice.



X2.

I can tell the difference. So, regardless of whether it's the physics or my mindset (or both) behind my perception of comfort - that's enough for me.


2012-10-08 3:17 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
Clempson - 2012-10-08 3:00 PM
dmiller5 - 2012-10-08 3:40 PM
RockTractor - 2012-10-08 2:34 PM
dmiller5 - 2012-10-08 1:04 PM my what a fine collection of facts and opinions that are not correlated!  I'm a civil engineer, and you probably can tell the difference about which you're running on... just like you can probably tell the difference running on different types of grass. or grass vs a dirt trail. This doesn't mean one will be more likely to cause injury.  As far as actual deformation of the surface goes; lets say you are running at a 180 foot strikes per minute cadence.  If a foot was on the ground constantly (which it isn't, you are in the air with no feet on the ground while you are running, but we can ignore that for now) each foot strike would be 1/3 of a second (60/180 = 1/3).  How much do you really think you can compress a surface with a modulus of elasticity of at least 2 MPa in .333 seconds (actually far less) with your measly 150-250 lb body?  No discernable amount by the standards of your body's ability to feel.  On top of that, the compression of your shoes is probably significantly more, and varies more step to step than the actual compression of the asphalt surface.

its all in your heads guys.

So.... which is it?

both.  you can tell the difference in surfaces based on lots of things, like texture for instance.  that doesn't mean you can feel how much you are compressing the surface

its not about compressing the surface...its about the damping coefficient and stiffness modulus. those two material/structural constants have a big role in determining the resultant forces of the impact between your shoe and the running surface.  just because the surface doesn't deform from each foot strike doesn't mean one surface isn't better at damping the force of impact and lowering the resultant forces on your joints.

I don't think you are nearly far enough along the stress strain curve for there to be a difference in the force transmitted back to the legs from the surface of the pavement.

2012-10-08 3:33 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?

famelec - 2010-04-27 11:37 AM A lot people say that running on asphalt is better than on concrete since is is "softer" and more forgiving on your joints.  My gut tells me that asphalt might give a bit for a 2,000 lb car, but is as hard as concrete for a 100-200 lb person.

Is there any scientific evidence that running on asphalt is easier on your body than running on concrete?  Any convincing anectodal evidence?

I'm moving from a place where I run 100% on asphalt to a place where I'd likely run mostly on concrete.....

Brian



 

Like lots of things - there's a difference, I'm sure, but not enough that you'll really notice after a little time making the switch.  The body will adapt.

 

So, my vote goes in the "No, it doesn't really matter" column.

 

 

2012-10-08 7:40 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?
My 2 cents.  I can run on concrete sidewalks or asphalt roads which are side by side.  I run on the asphalt because it feels "easier" to me, I just didn't know until now I was making a choice to run on the asphalt.  LOL!
2012-10-08 8:41 PM
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Subject: RE: Asphalt vs Concrete: Does it really matter?

With all due respect for science and numbers, there's something to be said for a psychological advantage and if asphalt gives it to you, then it matters.  Personally, I like running in the bike lanes on the street as much as I can.  I move to the sidewalk if/when I need to.  I don't think it feels softer but it seems smoother and there's usually less deformities in the asphalt.  Plus, I get to focus on chasing the white line when it's 430am an no one is around! 

When I run smoother, I run faster.  When I run faster, my form is better which, for me, means I'm hitting the ground with a softer touch as the cadence gets higher.  From that perspective, it'll save on impact wear and tear.  Cool

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