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If heel-striking is so unnatural, why do apes do it?

February 14th, 2010

In the wake of Dan Lieberman’s foray into the barefoot running debate, there’s an interesting counterpoint in the newest Journal of Experimental Biology from David Carrier of the University of Utah — the man who anticipated Lieberman’s 2004 “endurance running” evolutionary hypothesis by 20 years.

muybridge-walkingIn a nutshell, Carrier’s paper points out that heel-striking — a.k.a. “the devil,” as far as Lieberman is concerned — actually has advantages in some contexts. As the Utah press release puts it:

Humans, other great apes and bears are among the few animals that step first on the heel when walking, and then roll onto the ball of the foot and toes. Now, a University of Utah study shows the advantage: Compared with heel-first walking, it takes 53 percent more energy to walk on the balls of your feet, and 83 percent more energy to walk on your toes. [...]

Economical walking would have helped early human hunter-gatherers find food, he says. Yet, because other great apes also are heel-first walkers, it means the trait evolved before our common ancestors descended from the trees, [Carrier says].

The main point of the paper is that it’s curious that our foot anatomy is adapted to heel-strike while walking (i.e. we have a big, prominent heel), unlike most other mammals. But it’s a trait we share with all the other great apes, so it’s not something that was only created by the advent of thick-heeled modern shoes. As both Carrier and Lieberman have argued, many of our anatomical features seem to have evolved precisely to favour endurance running — but our heels, in contrast, seem better suited walking. This isn’t that surprising, the authors argue, given that both running and walking were likely essential to early hunter-gatherers.

Ultimately, none of this conflicts with the arguments put forth by Lieberman. Even if it’s natural to heel-strike while walking, the evidence suggests that early humans didn’t heel-strike while running. (Though the new study confirms earlier findings that there’s no difference in efficiency between heel-foot and fore-foot striking for running.) But as the barefoot running debate heats up, it’s interesting to note that heel striking has an evolutionary origin.

  1. Phil Koop
    February 15th, 2010 at 00:51 | #1

    While I am sold on your view of heel-striking in humans, I regret to say that comparisons to other apes seem an excuse rather than a reason for supporting you. Of the existing apes, Chimpanzees are the most closely related to us, but their modes of locomotion differ too greatly from ours to draw sound conclusions. Though the least arboreal of the great apes, they are still highly so, with feet adapted for grasping. And when they do resort to terrestrial locomotion, they prefer to do so on all fours – they aren’t “knuckle-draggers”, but rather knuckle-walkers. Furthermore, gorillas are also knuckle-walkers; since we share a more recent common ancestor with chimpanzees, that would imply that knuckle-walking is a more primitive character (in the the technical sense – the opposite of more derived.)

  2. alex
    February 15th, 2010 at 01:10 | #2

    Thanks for the comment, Phil. I should clarify that this post — and the comparison to apes — has no particular practical relevance to humans. It’s more of an interesting anthropological aside. Carrier points out in his paper that, since heel-striking evolved while apes were primarily arboreal (and they still are, for that matter), the trait didn’t evolve because of its efficiency for long-distance travel. The actual reasons for its appearance remain unclear — but the fact that it has been preserved in humans, he argues, is because it’s much more energetically efficient than forefoot striking for walking.

    All of this is merely incidental to the debate about barefoot running and heel striking, since humans appear to have always run (as opposed to walking) with a forefoot strike. But it does add a bit of additional complexity to the argument that human anatomy has evolved to maximize our endurance running abilities, since that’s clearly not the case for our heels.

  3. Rick S
    February 15th, 2010 at 15:10 | #3

    Oh the naked runner vs the naked truth!! The war of the Hired Guns is on! Who can hire the better scientist? The big shoe companies will not let their profits or the theory of their shoes go down without a fight—– “who has the better scientist on payroll” is the game now–and neither side actually needs to win—right? They just need to cast enough doubt on the “other side’s science and theory to keep some customers and thus, protect the company. Which is fine by me. By the way, I love your site, I love your integrity and wisdom !

  4. February 17th, 2010 at 01:44 | #4

    Alex, good post once again.

    After reading the study, I don’t think we can take much away from the running portion of it, in particular the comparison of footstrikes and economy.

    They took a bunch of people, not all runners, first off. One flaw in the study is that they focus on changing only what happens at foot strike. It’s very simple to change how your foot hits the ground by adjusting ankle flexion. But that’s not the big difference between habitual forefoot and heel strikers, as you know. Habitual or trained forefoot/midfoot strikers strike that way with that strike occuring pretty close to underneath their hips. Most of the time when you have someone simply adjust footstrike only, they still reach out with their lower leg.

    Lastly, I noticed that they had the runners hold their heel off the ground the entire time. With most people, that’s not how it happens. Most forefoot strikers seem to hit ball of foot first, then drop the heel down. You’ve got to do this to maximize the stretch shortening cycle on the calf and the energy return on the tendons. There’s been several studies that show that even most elite sprinters have their heel drop down.

    Good study on walking, but it seemed like the running portion was an after thought.

  5. alex
    February 17th, 2010 at 01:57 | #5

    Agreed, Steve — the study tells us something about evolution and anatomy, but not about running. And I think you make a very important distinction between the way habitual forefoot strikers land and how you land if someone just tells you to stay on your toes.

  6. Jope
    May 12th, 2010 at 09:09 | #6

    Hi,

    I wonder if you have actually read the so-called ‘counterpoint’ article you are referring to.

    David Carrier says that humans are efficient heel-to-toe walkers. He does not say that we are efficient heel-to-toe runners or that heel striking while running is normal. To the contrary:

    “‘Even when we run with a heel plant, most of the step our weight is supported by the ball of our foot. Lots of elite athletes, whether sprinters or distance runners, don’t land on their heel. Many of them run on the balls of their feet,’ as do people who run barefoot. That appears to be the natural ancestral condition for early human runners, he adds.”

  7. alex
    May 12th, 2010 at 10:50 | #7

    @Jope
    Thanks for the comment, Jope. Yes, I read the paper. I, in turn, wonder if you actually read my post. Nowhere did I suggest or even hint that “we are efficient heel-to-toe runners or that heel striking while running is normal.” On the contrary, I wrote that “this post β€” and the comparison to apes β€” has no particular practical relevance to humans. It’s more of an interesting anthropological aside.”

  8. July 19th, 2010 at 17:33 | #8

    @steve

    Finally, someone points out the stretch reflex (and, necessarily concomitant “triple extension” of vertical support) inherent in a correct ball of foot landing, versus the so-called mid-foot (flat footed), or heel striking landing in running!

    As I see it, the instant of vertical support is the transition from the previous stride to the next, and where the greatest ground reaction force is encountered. The stretch reflex can provide about half of this support, which reduces metabolic cost.

    Anterior ground reaction (heel strike), by the way, is unneeded because it’s a braking force. Posterior ground reaction (so-called “push off), when considered, seems rather odd in running, too. Immediately after vertical ground reaction, the ground reaction force drops below bodyweight, while muscle activity drops, as well. I believe this could call into question commonly described origins of propulsion in running. It could also begin to define different technique parameters β€” that there COULD BE technique parameters!

    But, paying attention to technique in running, because locomotion has been relegated to lower brain function since we let ourselves down from the trees can be an confusing challenge. We expect that we should just be able to run. And, we should. But, being told to let our soles coach us into correct running technique presupposes that we have the sensory acuity required to properly adjust, in the moment. I think we have Princess and the Pea sensitivity underfoot, but I haven’t yet seen that we have a real sense of how to run correctly when the protective layers have been removed. Runners may reach out to the ground and touch the ball of the foot first, but, landing well ahead of the center of mass, as many do, creates its own set of problems.

    What seems to be lacking in the descriptive science is a conceptual model of running, an accepted technique, or a standard by which to determine right / wrong. Leiberman suggests, as do others, that running is unique to each individual. I think humans are more alike than we are different, and that those same physical laws that apply to you, apply to me, too. Ducks fly the same way. Cheetahs run the same way. Barracudas swim the same way. Maybe there’s a case to be made for our running the same way.

    By and large, I think humans enjoy a culture of recreation instead of proficiency. And, because the human body is nearly as resilient as human behavior (habit) is difficult to change, we have historically gotten away with less than ideal function on many levels. We can get by on “good enough,” and even “not so good,” too. Analgesics, and anesthetics are sometimes helpful, but rarely is insulation instructive.

    As a barefoot runner I applaud the recent interest in natural movement, and hope that assigning some upper level brain function to running theory and practice will result in a healthier, happier population of runners / athletes sooner, rather than later. May it begin with Steve’s consideration of the stretch reflex…

  9. guano
    October 10th, 2011 at 16:54 | #9

    Apes and bears aren’t bipedal and they don’t have Achilles tendons or glutes. Comparing the bipedal human gait to that of a knuckle-walking ape or a quadruped bear is ludicrous.

  1. May 30th, 2011 at 13:39 | #1