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Saturday, July 3, 2010

Barefoot Running on Crushed Limestone

There are many surfaces runners traverse while pursuing their adventures.  To the shod runner, most surfaces are "runnable."  There's little difference between asphalt, dirt trails, gravel, or crushed limestone.   The barefoot runner has an decidedly different experience. 

Many surfaces present unique challenges.  Here are a few:

  • Asphalt: This surface can be abrasive if form is poor, blisters are common.  It can also get hot if exposed to direct sunlight.
  • Gravel: The size and frequency of larger rocks can dramatically influence the gravel experience.  If the density of large rocks is low enough to allow the barefoot runner to place their steps around the obstacles, gravel can be a fun approximation of technical trail running.  If the rocks are unavoidable, gravel can be nearly impossible to run barefoot.  
  • Dirt trails: My utopia.  Aside from the potential dangers of easily-avoidable rocks, sticks, root, acorns, or other trail debris, dirt trails are pure joy for the barefoot runner.
  • Sand: Sand is an interesting surface.  It is soft and forgiving, but also has the potential to hide bad form.  If running many miles on sand, it can become somewhat abrasive.
And the there's crushed limestone.  For those unfamiliar with this popular public trail surface, crushed limestone consists of various sizes of rocks ranging from fine dust to dime-size pebbles.  Most trails have a combination of sizes.  The pebbles are problematic because they are irregular in shape, multi-faceted, and contain sharp edges and points.
This past Thursday, I attempted to do a long run on a crushed limestone trail.  I made it 16 miles before using my huaraches.  This particular trail had a wide variety of pebbles.  

Some parts of the trail contained mostly hard-packed dust with an occasional pebble.  This surface was very runnable as it was exceedingly easy to avoid the larger pebbles.

Other parts of the trail contained a high density of larger pebbles.  This is also runnable as the points and sharp edges create a "bed of nails" effect.  The cumulative surface area of the potentially-painful pebbles does not allow a single point to poke your foot.  The result is a pleasant massaging effect.

An example of a high-density "runnable" trail

The majority of the trail contained a lower density of large pebbles, but not enough to allow you to avoid them.  The result- I would step on four of five sharp rocks with each step.  A singular sharp point is an easy adjustment... you shift your weight and relax your foot.  Several points are much more difficult.  It requires a light step to minimize the poking.

The experience of the 16 barefoot miles was analogous to a tattoo.  In the beginning, there was some pain.  The slight discomfort was enjoyable as it awoke my senses.  Yes, it is slightly masochistic. 

After a few miles, the pain subsided as my feet adapted to the experience.  It was if my body shifted into cruise-control.  Even the difficult areas were handled with ease.

Until about mile 12, the rough patches were equally distributed with the easy patches.  Once I passed that 12 mile point, the trail turned consistently difficult.  At first, it was annoying.  At about mile 14, I recognized the "annoying" feeling was actually mild pain.

By mile 15, the pain was disrupting my gait as I tried to adjust to minimize the discomfort.  I immediately noticed a quickly-developing pain in both knees from the altered gait.  At this point, all my attention was focused on form... which is a bad place to be.

By mile 16, I threw in the towel.  We were still a mile away from the "quarter of the way" point if we went the full distance (we didn't, we stopped at mile 36.)  It was at that point I went to the huaraches.  

The rest of the run went well, though we did encounter many sections that would have been runnable barefoot.  Needless to say, I was tempted to ditch the huaraches.  For the sake of my running partners, I left them on.

The lesson learned- crushed limestone will take more adaptation than what I currently possess.  That entire trail could be runnable barefoot, but I am not ready.


  1. I was glad to read this report. I've been eyeing some crushed limestone trails wondering....I'm still relatively new to barefooting, but those trails look okay from a distance. I think I'll hold off a bit before running them. I opted out of a race today that was on gravel. The organizer was surprised when I didn't want to wear racing flats which he thought would be fine. I've been barefoot/minimalist for long enough now that even flats seem awkward. Just can't go back!

  2. Nice report. I've been struggling with this surface for years. Currently I'm not up to going much more than 6 miles on this surface but intend on slaying this dragon. What kind of weekly barefoot mileage have you been able to maintain. Currently I run about 50-60 a week when training for marathons but can only must around 20-25 of it barefoot.

  3. I have tried the limestone and it is very challenging (I have not run for 16 miles on it but for about a mile, before i moved to safer and softer grass). But on another note, I have been training on asphalt and concrete with hopes to run a full marathon barefoot (currently finished 2 half's in Vibram Five Fingers)and I have developed two problem areas on my feet that I cannot get rid of, and hope that you or one of your fellow bloggers can help with some advise.

    .1 I have developed a blister on each of my big toes that keep breaking open after they heal and bleed once I hit the 4 mile mark on concrete or asphalt, by the time I reach mile 6 or 7 they feel like they have taken a couple of layers of skin off, and I have to put my shoes on if I want to keep running.

    .2 Secondly, my heels also develop a fairly substantial blister (not sure what to call it, its like the skin has separted from the foot with a layer of fluid between over a large area but not bubbled like a normal blister), which takes 3 to 4 days to go away usually by the skin falling off. I know I am not a heel striker (more of a mid foot stiker), so I believe this happens over a period of time with my heel contacting the cement or asphalt when my foot plants. How can I prevent these blisters or is there something that can toughen them up.

    Any advise

    A avid barefooter
    Winnipeg, Canada

  4. Yeah but dude, 16 miles on that stuff? Maybe you haven't reached the level where your feet don't touch the ground yet, but you're headed in the right direction. Congrats.

    But footwear shmootwear. How was the run?

  5. Yup, the "surface tension" of terra firma can have some interesting consequences. For the most part, it just feels really good...but very occasionally it actually breaks something, as it did yesterday on our run. Sigh... No worries though, happily, time heals. :-) Duncan.

  6. I also recently learned that ill-maintained asphalt can make a barefoot run rather roughshod and painful.

  7. I had tried running on asphalt and the experience was really awful. I got blisters all over my sole and it was really painful. As an alternative I tried some
    barefoot shoes instead.