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The Impossible Terrain: An Analysis Of What Cannot Be Conquered Barefoot

Posted by on Oct 19, 2011 | 14 Comments

Back in the day, I used to believe any surface could be run barefoot if you had adequate training.  The premise was backed by a simple philosophy.  Good running form would negate every potential problem a runner could encounter.

I fell into a classic trap- I took my experiences on roads, sidewalks, and minimally-technical trails and generalized those experiences to everything.  I’m going out on a limb, but those that believe it’s possible to run barefoot anywhere probably haven’t actually tried to run barefoot everywhere (cough, cough, like a certain barefoot runner that was kicked off Runners World, cough.)

I was wrong.

I found I could run on terrain that was initially nearly impossible, but training on that specific terrain eventually led to some level of proficiency.  At that point, my “extreme” conditions were limited to gravel roads, chip and seal asphalt, what I assumed were rocky trails, and temperatures between 40° and about 90°F.

At that point, I started running experimenting to see how far I could push the boundaries.  In the four or so years since the initial experimentation, I have pushed my own boundaries in regards to temperature and terrain.  I devised a list of variables that determine if any given situation can be tackled barefoot.  While individual experiences and abilities vary widely, the premise more or less holds true for all of us.  To represent this idea, I made this hastily-drawn not-to-scale graph that was introduced in a previous post:

As the graph illustrates, the more difficult the terrain and extreme the temperature, the more difficult barefoot running becomes.  Furthermore, the faster and longer you run on any given surface, the more difficult barefoot running becomes.

Walking or hiking, even on the gnarliest of terrain, is almost always possible.  Sprinting, on the other hand, becomes difficult if not impossible on all but the easiest of terrain. The question I’m interested in exploring- where is that possible/impossible line?

We know humans have definite physiological limits.  Nobody is bench pressing 5,000 pounds, dunking a basketball on a 30′ rim, or running a one minute mile.  I’d call those “hard limits.”  There are also limits that are just beyond what we’re capable of accomplishing, but may someday get there.  Bench pressing 1,200 pounds, dunking on a 15′ rim, or running a 3:30 mile may be possible someday.  Let’s call those “soft limits.”  Barefoot running has definite hard limits, but also soft limits.  Hard limits cannot be broken.  Soft limits can with proper training.  I’d LOVE to see someone actually push these boundaries.  More on that later… meanwhile, this is what I’ve learned:

The Variables

So what are the exact variables, that determine the feasibility of running barefoot?

1. Speed.  This is one variable I think where it’s possible to run faster barefoot at any given distance as long as terrain is not as issue.  The naked foot is lighter than any shoe, which should allow for slightly greater efficiency, ergo faster speed.  If the terrain requires any sort of evasive skill to avoid debris, it is likely shoes will allow you to run faster.

2. Distance.  Like speed, I don’t think this is a variable that is limited by being barefoot as long as terrain is ideal.  Shoes over long distances have problems, mostly due to moisture.  Bare feet do not have this problem.  If the terrain requires any sort of evasive skill to avoid debris, it is likely shoes will allow you to run farther, too.

3. Temperature.  I’ve been able to run several miles at temperatures down to about 24°F.  Assuming hot asphalt in the sun, my upper limit has been about 90°.  I know runners that have successfully run barefoot about 10° above my own extremes, but I think there are hard limits at both ends.  Nobody is running barefoot through Death Valley in July (Badwater), nor are they running  across Minnesota in February barefoot (Arrowhead.)

4. Terrain.  This is where it gets tricky.  Some terrain, like hard, clear surfaces such as asphalt roads or sidewalks, is very easy.  Hard-packed dirt trails are easy, too.  Clean grassy fields- piece of cake.  Terrain gets a little more difficult if you add some roots or acorns to the trail, move to crushed limestone bike paths, or add rough asphalt like chip and seal.  Still, those conditions are easily mastered with training.  Gravel roads are probably the next step in the “difficulty” progression, then snowy or icy roads.  Again, training will get you through these conditions.  The next step up is where real difficulty begins- the introduction of sharp rocks and/or ice.  By “sharp”, I don’t mean “pointy rocks that make you say “OW!”  I’m talking about shit that has a pretty good shot at cutting you with a sharp edge or puncturing your skin with a sharp end.  This is the stuff that will cause physical damage of you touch it with any degree of force.  There are several sub-variables” to this one, including vision, feel, and density of obstacles.

4a. Vision.  The ability to see where you’re running is important, but not always necessary.  With experience, it’s possible to run in complete darkness by relying on the ability to feel the ground with each step.  This ability decreases with speed and difficulty of terrain.  On very technical trails, like the type with the sharp rocks mentioned above, vision is critical.  Not only do you have to see where each foot will land, you have to assure the other foot has a place to land, too.  You have to “see” two steps ahead.  If you’re wrong about step one and inadvertently step on a sharp rock, you can mitigate the damage by relaxing and taking the pressure off that foot.  That requires the other foot to land to maintain balance, which is why you have to assure that foot has a place to land.  If vision is obscured to the point where you cannot “see” that second step, barefoot running becomes impossible.  This may be due to darkness, snow covering hard ice, leaves covering rocks, etc.

Sidebar #1– some people asked why I use a handheld flashlight when trail running at night.  It allows me to discriminate terrain better than a headlamp.  With headlamps, the light source is close to my eyes.  It’s nearly impossible to see shadows and depth, which makes the terrain appear flat (2D.)  With the light source away from your eyes with a handheld, the depth of shadows allows me to determine the height and  shape of obstacles (3D.)  Also, the ability to quickly move the light up and down and side to side can eliminate ambiguity.

Sidebar #2– some people also ask why I spread my arms when running downhill.  The quick answer:  Balance.  The longer answer:  Balance if I happen to step on something sharp with that first step.  If I’m running fast downhill and step on something sharp, the “relax” reflex kicks in and my other foot immediately searches for a landing spot to maintain balance.  Since I’m going fast, I’m outrunning my ability to “see” where the second foot lands.  If that foot lands on something sharp, I’m falling.  The outstretched arms help balance which keeps that fall in the “stumble” category as opposed to the “I’m losing teeth when my head bounces off the ground” category.  🙂

Vision is also influenced by sleep deprivation and fatigue.  Your brain’s ability to interpret the incoming sensory signals decreases, which is what makes barefoot 100 milers so difficult.

When vision is reduced or eliminated completely, the ability to navigate technical terrain decreases.  At some point, barefoot running with limited vision becomes impossible.

4b. Feel.  Ground feel is almost as important as vision.  This is the ability to immediately and correctly identify what is under foot.  In many cases, this is an unconscious, reflexive action.  The millisecond you step on something, your feet identify it as something that causes pain or something that doesn’t cause pain.  If it’s the former, your body reacts by preventing further downward force.  If it’s the latter, your body continues loading the foot as your weight shifts over that leg.  Also, if landing on an uneven surface, you will know by both the tactile sensation (part of the foot is touching a surface, part is not) and a proprioceptive sensation (foot is inverting, ankle is flexing, etc.)  This is what prevents injuries like sprained ankles and allows you to run on uneven surfaces fast.

Feel is always a tradeoff of wearing shoes.  The protection allows you a larger margin of error with foot placement.  However, any protection you gain is met with a corresponding loss of tactile and proprioceptive sensation, which often affects running form of barefoot runners.  This is the reason shoe selection becomes a tricky proposition- you have to weigh the costs and benefits of an increase in protection versus a decrease in ground feel.

“Feel” is also influenced by sleep deprivation and fatigue for the same reason as vision.  If you have adequate vision, you can run without any ground feel at all.

4c. Density of obstacles.  How closely packed obstacles are is more important than the characteristics of the obstacles themselves.  I’ll use the example of sharp gravel covering an asphalt road.  If the gravel is so dense you step on many pieces with each step, barefoot running is relatively easy.  You get a “bed of nails’ effect where many pointy surfaces are contacting your foot.  The cumulative surface area distributes your weight enough to prevent pain or injury.  This is why it’s relatively easy to learn to run on chip and seal asphalt.  also, if the gravel is spread out enough, it’s easy to land on the underlying asphalt and avoid the gravel altogether.

Barefoot running becomes difficult when the gravel density is thin enough where you always step on a few pieces but thick enough to make it impossible to avoid.  The same concept holds true for overly technical trails.  Small, sharp rocks usually isn’t a problem.  Neither are huge rocks.  It’s the golf ball to softball size sharp rocks that usually cause the problems.  Here’s a graph:

 If the obstacles are the sharp, injurious rocks mentioned above hit the top of that bell curve, AND they are combined with limited vision, barefoot running becomes impossible.  The situation is even worse running downhill.

My Real World Experiences

Earlier I mentioned I have tested my own limits extensively.  Living in the Midwest, I had ample opportunity to test my own temperature limits, especially on the bottom end.  I thought I had tested my trail running limits, too.  Then Shelly and I decided to become nomadic hobos. I was introduced to terrain that completely reshaped my paradigm of what I thought was possible.

Specifically, I experienced mountain running.  It redefined what I considered “technical.”  As it turns out, Midwest trails are exceedingly tame.  Even the roughest, least barefoot-hospitable trails pale in comparison to some of the conditions we’ve found.  Here are just a few such areas that I would deem “barefoot-impossible”:

  • Back country trails in Colorado:  The Rockies are aptly-named.  These trails featured long sections of jagged rocks that fit perfectly atop the bell curve above.  To make it more intimidating, these trails are never flat (see pic below.)  Even walking barefoot proved to be extremely difficult.  I’ve found similar rocks elsewhere, like Bear Mountain, NY.

  • Mud over granite in Ohio:  We found these gems on the Burning River 100 course near Akron.  The trails featured high clay content mud covering sharp granite-like rocks.  Flat ground was okay.  As your foot hit the mud, you were still able to feel the rocks underneath.  It was similar to running on snow-covered ice.  Hills were impossible, though.  Your foot would hit the mud, then slip backward or laterally.  The slipping would cause your foot to slide along the jagged edge of the rock, which immediately sliced the skin.  Laceration city.
  • Extreme temperatures.  Hot burns.  Cold either freezes or kills tactile sensation, which causes lacerations.  I know of people that go down to the teens (Rick Roeber) and several that go up to the low 100’s.  I think it’s safe to say that’s pretty close to the limit, especially over any significant distance.
  • Leaf-covered rocky trails along the Appalachian mountains: I’ve encountered this twice- once on the Grindstone 100 course and once in the Smoky Mountains of Tennessee.  The rocks were sharp and at the “difficult” density, then covered with leaves.  It completely eliminates vision, and the rocks are too jagged to rely on feel.  Here are some pics from Mt. LeConte south of Gatlinburg, TN.  The first pic is the trail covered with leaves.  It doesn’t look too bad…

…until you sweep away the leaves and see what’s underneath:

  • Any trail populated with debris like goathead thorns.  These little bastards are Hell.  They’re small and the same color as sandy dirt, which means they’re impossible to see.  They occur frequently enough to prevent the “second step” that I talked about before.  For example, if you sense the pain of stepping on one, you can successfully mitigate the damage by relaxing.  However, the next step with the other foot often steps on one, too.  The result- they drive into your foot or you take a header… into a trail full of tiny spikes.

And finally…

  • Most 100 milers.  The combination of rugged trails, time on feet (fatigue), sleep deprivation, and darkness make barefoot 100 milers remarkably difficult.  It would require perfect form and concentration for each of the half-million or so steps you’d take throughout.  One misstep could lead to a race-ending injury.  Some would be easier than others.  For example, a few like Rocky Raccoon, Burning River, Philadelphia, Ancient Oaks, Iron Horse, Hallucination, Mother Road, etc. are run on relatively flat, smooth courses.  There are the races that get a 1 or 2 terrain rating on the Ultrarunning Magazine calendar.  Someone will run one of these barefoot, probably in the very near future.  Anything with a “3” terrain rating would be extremely difficult, like Moab, Javalina, or Umstead.  I would be genuinely surprised if anyone ever runs those barefoot.  I would be absolutely shocked if anyone ran a 4 or 5 barefoot, like HURT, Wasatch, Western States, Grindstone, Massanutten, Hardrock, Barkley, etc.  I would say those would be impossible.  Hell, I’d be impressed if someone ran a 50k rated at a 4 or 5.  The 50 I ran was only a 2 (North Country Trail, 2007.)

Why Bother?

Barefoot running clearly has limitations.  So why bother even attempting to traverse this kind of terrain?

Josh Sutcliffe gave a good answer in his recent post– training.  Pushing your limits on this type of terrain will improve your abilities to run on any technical terrain, even when wearing shoes.  You develop what I refer to as “trail craft”, or the ability to use a combination of vision and feel to navigate excessively technical terrain.

The 100 Miler Challenge

I spent considerable time pushing my own barefoot boundaries in regards to 100 milers, but ultimately gave up when the time commitment trying to run the “easy” 100s barefoot prohibited me from experiencing the rugged mountain races.  I’d LOVE to see others continue trying to run a 100 barefoot.  As far as I know, Todd Ragsdale was the last to attempt it at the 1020 Rocky Racoon.  I think he would have made it had the temps not plummeted before the race.

If anyone thinks they may be up for it, let me know.  The more difficult, the better.  I’ll help you out in any way possible.  Yes, I want someone to prove me wrong.  😉


As of right now, I think it is safe to say there’s some terrain and conditions that are impossible to conquer barefoot.  Lots of people say you can run anywhere barefoot, but there aren’t too many people that seem to be willing to actually try running anywhere barefoot.  Testing your own limits can be a great way to continue building skills.  In the future, I hope to see people surpassing what I think are the upper limits of human barefoot running ability.


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  1. kddubb
    October 31, 2011

    Hey, great post. From my experience training and running the Pikes Peak Ascent, I have to admit that I think there are definitely limits to barefoot. But it’s also an addictive challenge to expand your own limits too.

    You allude to one more variable, but don’t call it out separately…and I think it should be. GRADE. Meaning uphill or downhill grade. Going uphill is harder than flat and going downhill is much harder than going uphill especially when the other variables are in the mix. Some of it has to do with the extra downward force on the feet and some of it has to do with sheering forces on the skin.

    From experience, going 13 miles up Pikes Peak is definitely doable even decently fast (I’m still hoping I can PR in a couple more years). However, coming down Pikes Peak, even walking slowly, seems almost out of the question at this point (especially when you have to do it after going up first for the Pikes Peak Marathon). That’s the goal though…so hopefully I’ll conquer it eventually.

    Again, thanks for the post!

    Shoes are cheating,


  2. Natural Running = Paleo Running in the Modern World? :
    October 23, 2011

    […] it, picking your way carefully. Jason Robillard, creator of Barefoot Running University, wrote an excellent pieceon this […]

  3. Bill H
    October 23, 2011

    Like the post- another consideration is load. I do lots of pack runs in boots. Have not attempted to run under heavy loads barefoot. Even horses need shoes for carrying heavy weight. Those rocks underfoot feel a lot sharper with an extra 30 or 40 pounds on.

  4. Rob
    October 21, 2011

    While I’m not an extreme barefooter, or barefooter in general (just a dabbler), I can relate to the mindset. While my primary passion is running (mostly minimalist) and ultra running in particular, I’m also very into unicycling; both on and off road. So I often hear the same sorts of arguments from my two wheeled acquaintances about why I try to ride certain “impossible” terrain on my unicycle when I could easily ride it on two wheels. I think they, like some of the shod runners towards the barefooters, miss the whole point! So while I don’t run as minimally as you all, I certainly take my cycling approach very minimally!

  5. Erik Lee Skjon
    October 21, 2011

    Great to see guys out there testing the limits, but I enjoy running best when I enter a nice meditative state. Chip ‘n seal is fine, and temps down to 20 degrees, but conditions harsher than that tend to take me out of my zone. I think the true value of extreme barefoot running is that it can teach us stuff about barefoot running in general that running under more favorable/less risky conditions can’t. Kind of like applying some of the science learned in serious bodybuilding to a more humble, everyday strength-training routine.

  6. Dave Tensen
    October 21, 2011

    Firstly, love the blog Jason. Your honest and open writing is inspirational, generous and informative. I’ve been BF running for just over 7 months and have just started hitting the trails. So far, I’ve carried my Softstars or Runbrancas with me for the tougher terrain or when I feel I’m going to do my skin or feet damage by barefoot running… and you know what? Initially I did feel guilty but on the other hand we see even the iconic Tarahumara where sandals for their longer runs because it made sense. I guess there is a challenge of doing tougher and longer terrains barefoot but it does come at a cost – and sometimes that cost is missing out on a finish, suffering avoidable injury or otherwise. At the end of the day I