Tag Archives: heel-striking

The “heel-striking” running gait doesn’t observe the requirements of the human body’s mechanical paradigm.

Those who say that the midfoot strike is the “ideal” running stride often conclude that midfoot striking is “better” for a variety of reasons. One of those reasons is that, allegedly, the midfoot strike is more “natural” than the rearfoot-strike (also known as the heel-strike).

It’s a bad idea to call the midfoot strike more “natural”—aside from the fact that the allegation is wrong: humans use a variety of different footstrikes for a variety of different activities. Rearfoot striking ahead of the center of gravity is the default walking strike. Rearfoot striking is also used to abruptly halt forwards momentum, and sometimes, to turn by using the heel bone as a pivot. Conversely humans use a very anterior (forefoot) strike during the acceleration phase of sprinting.

In short, the problem with this “natural” argument is that human feet strike the ground all over the foot map.

So stop calling it natural.

Which is why I prefer to adopt a more technical term: paradigmatic function. This term means that a certain function X is more in line with a particular structure, or a particular configuration of a structure.

For example, variable-geometry aircraft—those which have the ability to “sweep” the wings back from an extended position to create a triangular shape (such as the F-14 Tomcat)—use the swept-back configuration for combat and supersonic flight, while they use the extended (regular) position for takeoff and landing. For the F-14 Tomcat, the paradigmatic function of the extended configuration is takeoff and landing, whereas the paradigmatic function of the swept-back configuration is combat and supersonic flight.

tomcat

Although it is no doubt possible for the F-14 to land with the wings swept back and enter combat with the wings extended, there are two things to consider: (1) each configuration works better for each activity, meaning that (2) each configuration “solves” a different problem: the swept-back configuration allows for greater maneuverability and speed, while the extended configuration allows for greater stability and reduced speed during landing.

Central to systems thinking is the idea that every system (or configuration of a system) is built to solve a particular problem. For example, a system with a branching structure, like a tree, a lung, or a network of roads, solves the problem of getting the maximum amount of energy or nutrients to and from various places with the least amount of effort. The shapes of systems always correspond to the most parsimonious way to solve a particular problem. In a very real way, you can think of all systems—and each individual configuration of those systems—as solving a problem that is specific to each system or configuration.

The very same goes for walking and running, the two important gaits—the two functional configurations—of the human body.

Although it would seem easy to say that these two functional configurations are “walking” and “running,” it’s better to get at this conclusion in a more roundabout way:

In terms of the stresses absorbed by the body, the most important difference between walking and running is that in running, there is a flight phase, while in walking, there isn’t. This means that one of the things that the body needs to do while running is absorb the shock of landing, while in walking, this particular need is largely absent.

This theory is largely borne out by looking at the muscles used during walking: the largest muscles in the body—the gluteus maximus, the psoas major, and the hamstrings—are largely inactive.

Because of this, the knees remain locked during the walking gait. This means that by walking, the body “solves” the problem of preserving energy while remaining in motion; that’s what the walking configuration is for.

Because a necessary component of running gait is the absorption of shock, the landing portion of the running stride should incorporate a shock-absorbing motion. So, in order to figure out what kind of motion comprises the landing portion of the running stride, let’s review what a “purely” shock absorbing motion looks like: landing from a jump.

When we land from a jump, our hip and leg mechanism works largely like a shock-absorber: we land on our midfoot or our forefoot, and all the joints of the lower extremity go from a lot of extension to a lot of flexion in less then a second, meaning that the hip, knee, and ankle all flex together. (This is known as triple flexion). This means that the paradigmatic function that the body uses to absorb shock is triple flexion. Similarly, in order to jump again, the body extends the hip, the knee, and the ankle simultaneously (which is known as triple extension).

Exchanges_Triple-Flex-Ext

In order to create triple flexion and triple extension, the body must recruit the largest muscles of the body, including the hamstrings, gluteus maximus, psoas major, and quadriceps. In other words, the triple flexion/extension configuration solves a very different problem than the one solved by walking: it allows the body to safely absorb the energy of impact, while powerfully exerting force against the ground.

Because running necessarily has a shock-absorption component and a takeoff component (because of flight time), it stands to reason that, during running, triple flexion and triple extension should form an integral component of the contact and pushoff phases (respectively).

This is where it gets problematic. The typical heel-strike (overstriding with initial rearfoot contact) plays out very differently from triple flexion: as the foot strikes the ground, the knee is mostly locked but the leg is stretched out in front and the foot is raised. The hip is in flexion, the knee in extension, and the ankle in flexion. This means that the shock absorption capabilities of the leg are reduced—and because the leg flexes less, it has a lower capacity for pushoff.

heel-striking

(The lower achilles tendon loading of heel striking as compared to forefoot striking may attest to this).

I’ll leave the issue of heel-striking under the center of gravity for another post. For a taste of why it might be problematic, try jumping up and down in the same spot while landing on your heels. It’s extremely difficult.

In contrast, the midfoot/forefoot strike is a great example of the triple flexion/triple extension principle at work: When you land on your midfoot, your leg compresses like an accordion: the ankle, knee, and hip create a zig-zag shape, which straightens as you push off. Midfoot striking adheres strongly to the musculoskeletal configuration used for shock absorption/propulsion movements.

forefoot-striking

In my opinion, the best way to know if you “are” a heel-striker in some essential sort of way is to jump up and down, and to see if it is easier for you to absorb shock by landing on your heels than by landing on your midfoot or forefoot. (Unlikely). If that isn’t the case, and yet you heel-strike while running, it might be time to look at muscular imbalances and power leaks, particularly in regards to muscular interactions at the hip area (illiopsoas, lower back extensors, gluteus maximus, quadriceps, and hamstring).

And then, embark on the long road of responsibly changing your gait.

An analysis of the paradigmatic features of midfoot-striking and heel-striking.

The term “heel-striking” shouldn’t just refer to which part of the foot hits the ground first. Even in the common parlance, it should refer to the collection of neuromuscular gait features across the body that contribute to a type of overstriding in which the heel lands first, ahead of the center of gravity.

When I write the words “heel-striking,” this is invariably what I mean.

This way, we can neatly sidestep the conversation of whether someone landed on their heel under their center of gravity, or only “appears” to heel-strike. Let’s do away with reductionist analyses: let’s make it about something else than just “the strike.” The most widespread way in which the western runner overstrides is by heel-striking.

In a previous post, I reviewed how there is a paradigmatic body geometry to midfoot-striking, which corresponds to a paradigmatic pattern of muscle use. Heel-striking is no different.

When I say “paradigmatic,” I refer to the core components of the stride; to its most generalizable features. For example, the paradigmatic body geometry of midfoot-striking consists of a full-body arch, which begins at the base of the head and ends at the heel.

Establishing the paradigmatic features of types of running strides allows us to observe those features and make reasonable predictions about them. If you look at a runner who appears to be heel-striking, and yet is creating a full-body arch starting from the base of the head and ending at the pushoff heel, you can be reasonably certain that if you look closer, you will actually find this runner to be midfoot-striking. In other words, you can know that Meb Keflezighi’s apparent heel-strike (left), is actually a “proprioceptive heel-strike”—rather, a “disguised” midfoot-strike—just by looking at the continuous arch made by his leg and back at pushoff. (This video makes my point rather well). You may notice that other noted forefoot-strikers create very similar arches:

elite arches m

Because every person has a slightly different body geometry, the specifics of their stride will be slightly different. But these specifics are much more similar to each other than it is usually claimed. For example, in the post previously mentioned I reviewed how, necessarily, for all humans, dynamic strength is necessarily achieved by creating a series of consistent and symmetrical arches with the body’s bone structure. The reason this applies to all humans is because it applies to all structures. The integrity of every possible structure—from the Hagia Sophia to the plantar vault—is subject to the symmetry and consistency of its arches.

From this idea, we can extrapolate that no human can be the strongest version of themselves without creating the most consistent and symmetric arches across the body. Therefore, when you look at the differences betwen midfoot-striking and heel-striking, the differences in body geometry stand out starkly: unlike midfoot-striking, heel-striking paradigmatically breaks the full-body arch that makes the midfoot-striking body so resilient.

There may be a few runners out there for whom a true heel-strike doesn’t break this full-body arch. There may even be others who can land on their heels, under the center of gravity, without breaking this arch. But paradigmatically, the stride difference between forefoot-strikers (left) and heel-strikers (right) looks like this:

heelforefoot1

As mentioned before, a paradigmatic body geometry corresponds to a particular pattern of muscle use. In the above graphic, you can observe major differences between midfoot-striking and heel-striking in the neuromuscular paradigm of both the extensor muscles used during pushoff (red) and the flexor muscles used during the swing phase (blue). Of course these two types of body geometry load different tissues in different ways. That’s the point.

The most important differences are (1) the reduced iliopsoas function for the heel-striker (depicted by a grayed out X at the hip), (2) the reduced function of the upper back extensors (grayed-out X at the back), and the concentric activation of the quadriceps muscle for the heel-striker (blue arrow at the thigh).

The heel-strikers’s upper leg is in a bit of a predicament: during the swing phase, both the quadriceps (front thigh muscle, blue), and the hamstring (back thigh muscle, blue) are active at the same time. This is a problem because, when the leg is forwards of the hip, the hamstring flexes the knee, while the quadriceps extends it. This means that two muscles of the body which perform opposite functions are active at the same time, pulling in opposite directions. And this is happening as the leg is nearing the ground—during the landing phase—which means that two of the major muscles of the body are fighting each other, and they are doing so at the very moment that the body is about to slam into the ground.

This isn’t a problem for the midfoot-striker: the fact that the front knee is bent, and near the height of the hips, means that the quadriceps is largely inactive at that stage. Full quadriceps activation only occurs towards the end of the pushoff phase (front thigh muscle, red).

Because athletic power is generated through the creation of consistent and symmetric arches, any running body will always be the most powerful version of itself as a midfoot-striker. Furthermore, the body is designed around these principles: because load-bearing structure (the arch) is most consistent when the body is powerfully midfoot-striking, the body is at the peak of structural resilience when midfoot striking. Given that resilience is a hallmark of systemic integrity, this means that a systemic analysis of the body can only basically conclude that the human biomechanical system is operating at its “peak” when it is midfoot striking.

Similarly to the heel-strike, the midfoot-strike doesn’t refer to the part of the foot that hits the ground first. It refers to the constellation of stride components (such as the creation of a full body arch), that allows this part of the foot to hit the ground first.

This post shouldn’t be construed to mean that we should ONLY midfoot-strike. There may be plenty of reasons to heel-strike, such as rapid deceleration, and the opportunity to use the heel bone as a swivel, in order to turn quickly. However, for the purpose of producing safe and sustained forward motion, no type of stride will yield results that are as consistent or as powerful as those allowed by the midfoot-strike.

From maximalist to minimalist footwear (and back): a lesson in resilience, and in “shifting the burden” systems.

The popularity of the trend of minimalist (zero-drop, low-cushioning) shoes has coincided with a sharp increase in running injuries, according to some sources. This has caused a large amount of community, media, and legal blowback on minimalist shoes, the most salient of which is the recent class-action lawsuit against Vibram, for misleading advertisement.

Misleading advertisement should always be punished. Vibram peddled their five-fingers shoes as the solution to running injuries. They are not. They should never have been advertised that way.

But this blowback has created an unfortunate tendency: blaming the minimalist shoes themselves as the cause of injury.

They aren’t the cause. Although this may seem contradictory, it is the fact that so many people get injured when switching from “maximalist” (shoes that are highly-cushioned; often with an elevated heel) to minimalist shoes—but not vice versa—that suggests that minimalist shoes are better for the biomechanics of human running.

This apparent contradiction can be resolved—but in order to do that we must look at the issue from a systems thinking perspective. And for that, we have to begin with the concept of “resilience.”

Continue reading From maximalist to minimalist footwear (and back): a lesson in resilience, and in “shifting the burden” systems.