Tag Archives: Running

Principles of Training

Want to change your stride safely? Learn about your body.

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In my last post,  reader Ana Maria Castro Monzon commented:

“Great contribution! something that happens to me eventually when I’m running is that I feel that I run too slowly. I identified with “I’m just a slow runner.” How can I observe the alignment of my body when I run to improve my step?”

That’s the million-dollar question. I’ll say again what I answered in the comments: aside from going to a gait specialist, the best thing that you can do is observe, observe, and observe.

Most of us don’t really zoom into what we’re doing when we run. But if we did zoom in, and we watched and felt our body move, we would feel the slight disparities in our pushoff, the small differences in our arm swing, etc. That’s the very first step. Simply stated, look for differences.

First, we need to see that something needs to change, in order to change it. And when we develop experience in observing the motion and shape of our bodies, something happens. Just like when we develop experience observing brush strokes on a canvas, we develop an intuitive awareness of what’s wrong, of what’s missing, or what should be removed.

Observation and introspection are the key to developing this intuition, which later translates into knowledge. Why? Our bodies are systems, and systems are like puzzles: every single piece has a particular place in the whole, and its shape and color reveal its place relative to the others. In our bodies, every muscle, bone, and tendon has a particular place, and all of these parts function relative to every other. When one of these parts is functioning incorrectly, this reflects on itself and on the parts that surround it: when you put a puzzle piece in the incorrect location, not only does it seem out of place, but the pieces that surround the spot where it should have been are also negatively affected.

In the human machine, not a single part is superfluous, or out of place. Just like when you look at a car’s engine block: even if you don’t know much about cars, or engines, and at first glance you swear that one of its parts is superfluous—that it’s there just because, for “no rhyme or reason”—you’ll likely find that it has a very specific function, that you couldn’t pinpoint because you weren’t an expert.

This is the story of the appendix: some 20 years back, it still was thought that the appendix was a remnant of evolution. People would jokingly say that its only purpose was to get infected so that it could be cut out. But now we know better: the purpose of the appendix is to safeguard intestinal bacteria in the case of diarrhea or disease, so that the intestinal flora has a chance to repopulate.

All systems, across all domains, function largely like this. If something exists, it is there to perform a certain function. And when we introspect about our bodies and observe them, we’ll realize two things: first, that our bodies are systems, and second, that if we’re slow, or sick, or injury-prone, we can be certain that it is because some part is not doing its job, and certain that it’s not because we are slow, or sick, or prone to injury.

Further introspection will reveal what part (or parts) that is.

Even more introspection will reveal what to do about it.

And then there is the research. Although not every one of us has to become a physical therapist or a doctor—who are experts in all bodies—there is no good reason why each one of us shouldn’t become an expert in our own body. That’s the path that will take us towards being injury-free, and towards speed. While some of us may just want to be told what to do by a coach or a physical trainer, firsthand knowledge of our bodies is the most invaluable tool. Let me put it to you this way: two-thirds of the way into a marathon, we can be wondering why we’re getting hamstring cramps, or we can be exactly sure why we aren’t. There may be a few shortcuts to success, but there are no shortcuts to excellence.

Biomechanic Issues

Understanding our own imperfections isn’t just for self-acceptance; it may help us reach greater athletic heights.

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In every sense that matters, nobody’s perfect. Not physically. Everyone’s body is slightly asymmetrical. We have to keep that in mind when we train: those asymmetries are natural, and we should take them into account. Trying to create the “perfect” body—a body that is perfectly symmetrical—will mean that our bodies are less functional, because part of our biological systems will be devoted to maintaining those artificial symmetries.

A recent article discusses this at length, from the perspective of CrossFit. It makes the point that a lot of CrossFit injuries occur because of too much symmetrical training with an asymmetrical body: since we have a dominant side (larger, more powerful, more easily trained) and a non-dominant side (smaller, less powerful, less easily trained), training both sides “equally”—say, by doing barbell squats that load both sides equally—we are actually contributing to our body’s asymmetry.

We should train our non-dominant side more than our dominant side: when we get tired during a marathon, our form will collapse first on our non-dominant side. Then our dominant side will be forced to pick up the slack. Even if our dominant side is super strong, the mechanical energy is no longer translating properly from our bodies into the ground (and vice versa), eventually leading to injury.

But there’s more to this than just training. Lateral differences in people’s bodies have important effects on how mechanical energy is translated into the ground. When we run, it’s important to push off with the foot tripod (a.k.a the entire foot, with the weight on the first and second metatarsal). However, in order for both feet to do this when we have two different-sized left and right legs, the muscles of one leg need to work differently from those of the other: muscular asymmetries must be created in order to balance out skeletal asymmetries.

A right-dominant person’s right side is typically larger than their left. In the case of their hip bones this means that the right hip will be wider and longer than the left. (Their right femur is further away from the body’s centerline than their left femur). This means that the right foot is prone to evert (rotate outwards) more than the left. Supposing that the right foot pushes off correctly (with the entire foot tripod firmly planted), the left foot is likely to naturally underpronate during the swing phase, which means that this foot is likely to push off with more weight on the outer metatarsal bones.

In order to make the pronation (and therefore the pushoff) equal between the left and the right foot, the relevant hip muscles (usually hip abductor muscles) at the left hip, leg, and lower leg must be correspondingly stronger than those on the right side.

You see this happen in a lot of elite athletes, from Buzunesh Deba’s right leg swing to Haile Gebrselassie’s right arm swing (seen best at 1:47). During the swing phase, Deba’s right leg rotates inward slightly more than her left leg (and her right hip is consistently higher than her left). Similarly, Haile’s right arm ends the upswing with his hand just above the collarbone, while his left hand ends up just below. (These asymmetries are very slight because both these athletes have a very clean gait). Possibly, these athletes’ muscles are pulling asymmetrically in order to compensate for slight asymmetries between their right and left sides. These seeming imbalances allow their legs and feet to translate the mechanical energy generated by their bodies into the ground in the most efficient way possible. Trying to “correct” these asymmetries would likely result in a reduced athletic output.

Deba’s and Gebrselassie’s bodies are quite simply done pretending that they’re symmetrical. Neurologically, muscularly, and skeletally, their bodies are quite in touch with their own imperfections.

I’m making a case for self-awareness and self-acceptance. And I’m certainly not saying that self-acceptance will magically grant you good biomechanics. But biomechanical acceptance isn’t that far removed from the physical acceptance we need when we look at our bodies in the mirror. Not really.

None of this means that “perfect” symmetry is the ideal situation. Dominance is something that happens naturally, in order for us to be able to move the body asymmetrically. Having a dominant hand is far from a drawback: it allows us to write, paint, or to throw a javelin. Neurologically speaking, dominance lets both hemispheres of the brain provide greater computing power to a single extremity, resulting in much finer movement, and much greater skill.

Furthermore, the organs of the body aren’t arranged perfectly symmetrically: the heart is slightly on the left side, and the liver is on the right, for example. Because of how the body is organized, weight is distributed in odd places. More blood reaches some parts of the body than others, and dominance means that the touch, and proprioceptive receptors of some areas of the body are getting far more stimulation than others. The body grows differently in different places, and that’s a good thing.

But some of the most important movements we can make harness the body’s symmetry: running and walking. We somehow need to reconcile the need for symmetry with the need for asymmetry. Because each of us are different in different ways, we each reconcile those needs differently.

It’s not easy to reconcile these things. When we don’t have a lot of experience moving our bodies, our neuromuscular system makes the computationally simplest assumption: that both sides of our body are identical in length, width, height, and weight. It takes the brain a lot of data mining (from a lot of training) for our mental map of our bodies to include our biomechanical quirks and musculoskeletal idiosyncracies.

Training isn’t just about self-improvement. I believe that, above all, athletic excellence is about self-knowledge. Firsthand knowledge of our bodies leads to better, safer, and more efficient training. But it can also lead to a much better athletic experience, with much greater personal satisfaction.

Uncategorized

Can everyone run?

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A few weeks ago I was pulled into a conversation about running in La Paz, Mexico. I was asked incredulously by a good friend whether running was for everyone. In honor of the Baja 1000 off-road race, which recently concluded in La Paz, I answered with this:

“In order to run properly, a lot of us have to shake off the rust, change a few parts, and do some major tune-ups. And even though a few people out there are trophy trucks, every last one of us is at least a Jeep.”

Only one person can win the Boston Marathon every year, but (barring severe injuries and deformities), every one of us can aspire to run a marathon with the certainty that we will finish the race as healthy as we started it.

Shout out to the Vildosola family and racing team: good friends and constant winners of the Baja 1000.

Biomechanic Issues

Running “correctly” will mean different things for different people—up to a point.

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Next time you go see a marathon, go look at the elite runners—and then look at everyone else.

You’ll see that elite runners run like little toy soldiers: although they have different body types, their running forms are all nearly identical. The further back you get in the pack, the more “variety” of running strides you’ll see. In other words, across all humans, there is a specific recipe for speed.

Our bodies are all different. Some of us have big feet and short calves, others have long calves and really short arms. When a runner has really long legs but small feet, it becomes really easy for the knee joint to open and close: even though the feet are far away from the hinge (the knee joint), it doesn’t take a lot of power to move them because they don’t weigh very much.

In comparison, a runner with short legs and big feet might use the same amount of energy to open and close their knees. This short-legged runner is at a disadvantage, however: shorter legs means that they cover less ground with each gait cycle, meaning that more energy is expended across the same distance.

However, these differences don’t mean that different runners should use different stride types or different body positions. Achieving a “correct” stride will mean that for one runner, the parts of their body will be at certain angles relative to each other, while for another runner, those angles will be slightly different.

But our bodies all express strength in the same way.

For example, let’s suppose that somebody has a really short abdomen but a really long chest. This person may be inclined to hunch down to lift a heavy object, instead of bending their knees. For them, it may be simpler to stretch and contract the longest part of their upper body, their chest, instead of bending their knees, which is what they should do, mechanically speaking. In other words, this person has to work much harder to develop the muscles that hold their lower spine rigid (back extensors, illiopsoas), in order to safely be able to perform this maneuver. But despite these differences, the only mechanically feasible way to lift heavy objects is by bending from the knees.

Similarly, there is only one mechanically feasible way to run: by forming a smooth, unbroken arch from the base of the head to the ankle of the leg that’s pushing off the ground. This arch can only be formed when there is a very pronounced knee drive with the opposite leg (which means that the knee continues to be fully flexed at the end of the swing phase).

Because of individual differences such as those mentioned above, certain runners will have to work a lot harder than others at developing certain muscles, in order to create this continuous arch.

In my case, I have short legs, a short lateral arch (of the foot), and a long medial arch. Without going into the nitty-gritty details, this means that it is very easy for my foot to supinate too early in the running stride. Note that this does not mean that I am “a supinator”—or whatever. This means that my anterior compartment (hip abductors and hip flexors) has to be significantly more powerful than if I had longer legs and shorter feet, in order to maintain a midfoot strike while still using the entire foot tripod for pushoff.

My body has to work harder to keep my foot “more” pronated, and my leg “more” everted, throughout the  running stride, because the muscles that cause my foot to supinate are longer (and therefore get powerful more easily) than the muscles that cause my foot to pronate.

This means that the “untrained” version of my body (without a strong anterior compartment) wants to overstride. Why? Because in order to push off with the entire foot tripod, my body wants to start the contact phase when my foot is at its most pronated. In other words, because I supinate early, my body wants my foot to contact the ground early—and the easiest way to do that is by overstriding.

Furthermore, the only way for that untrained version of my body to midfoot-strike is by contracting the soleus muscle early in the contact phase. In order to go from the contact phase to the stance phase, my ankle has to dorsiflex. But because the soleus was already contracted, it has to work eccentrically in order to allow for this dorsiflexion. This form of midfoot striking put a huge eccentric load on the soleus, which means that my calves can get really really tight really fast if I don’t work heavily on strengthening my anterior compartment.

When I first started running for real, that’s exactly how the story went. My calves were chronically tight, and the answer to that was in developing my frontal compartment. Although different people may have to develop slightly different muscles (for example, someone may need a quadriceps muscle whose lateral head is relatively more powerful than the medial head), the answer for basically everyone who overstrides, or has posterior muscle tightness, is to strengthen the frontal compartment in some fashion.

My end goal was to create a particular structure—a structure which can hold a lot of tensile force, which is firm yet mobile, and which is correctly aligned relative to the force of gravity. As I mentioned above, that structure is a smooth, continuous arch from the base of the head to the ankle. Going about the process of creating that means something slightly different for me than it does for anybody else on the planet.

But nobody will be the most resilient (or fastest) version of themselves without first creating that arch.

Training Ideas

A few ideas for generalized injury-prevention for runners.

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As I often discuss here, I don’t believe that injury-prevention should be put in a different category from athletic training. Injury-prevention isn’t something you should do on the side. It should form an integral part of your training. Why? Because injury-prevention is all about resilience, and as far as the human body is concerned, resilience means using more muscles to achieve the same task.

It doesn’t matter what athletic discipline you practice: running, golf, or martial arts. The more of your body that goes into whatever movement you’re doing, the better off you’ll be. And that means one thing above all others: use more muscles.

That’s why a lot of injury-prevention websites for runner’s knee focus towards working the small muscles—gluteus medius, hip adductors, foot dorsiflexors—a.k.a. all the neglected ones. By putting all of these muscles in play during athletic activity, the body not only becomes more resilient, but more powerful.

In other words, the more resilient you can make your body, the more powerful it will be.

So how can we apply this to running?

One of the main problems most runners experience is that the posterior muscles (calves, hamstrings, glutes, back extensors) become too developed, since they have the most vital functions in the running stride: the first is concentric—extending the leg and back to push against the ground. The second is eccentric—arresting the body’s forward lean so that the runner doesn’t crumple forwards. With a few exceptions, the anterior (frontal) muscles main function is to work opposite to the posterior muscles, in order to allow the runner to lift the leg forwards during the swing phase.

(Think of it this way: muscles at the back generally move body parts backwards, and muscles at the front generally move them forwards).

This means that the most common form of muscle imbalances, which often lead to lateral knee pain and other ailments, are rooted in a dominance of the posterior muscles over the anterior muscles. The most basic thing that any athlete can do, for the purpose of preventing injury—and making their running stride more powerful as a side-effect—is to develop the anterior muscles so that they can move more powerfully.

Given all of this, injury-prone athletes should focus on exercises that strengthen the anterior muscles:

  • Sit-ups that emphasize balance through core activity (such as those shown in this video).
  • Because the gluteus maximus—the most powerful posterior muscle—works not only to extend the thigh but to abduct it (rolling it away from the body), it’s necessary to work on the adductors (which roll the hip in), in order to balance out these muscle groups. Leg/Knee raises help address this. The closer you bring the legs towards the chest, the more you will emphasize the inner abdominal muscles (such as the illiopsoas), as well as the hip adductors.
  • Hanging leg lifts. Doing it with straight legs works the obliques of the core and thigh.
  • Bicycle crunches are also amazing for balancing all of the core/hip muscles.
  • This exercise is great for strengthening to frontal calf muscles.

Even though running is all about triple extension (of the hip, knee, and ankle), you need to be able to flex those joints, in order for your extension to have a greater and greater range of motion. The stronger your posterior muscles get, the more you’ll find yourself “staving off” muscle pain by stretching. The ultimate answer is to strengthen the anterior muscles, so that they can interact properly with the posterior muscles.

For a sport like running, you can count on the posterior muscles to take care of themselves. It’s the anterior muscles (and obliques) that you have to worry about. I love this quote by The Gait Guys, which captures all of this in one simple thought:

“Develop anterior strength to achieve posterior length.”

Biomechanic Issues

On the importance of the Internal Obliques.

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I just read a very interesting article on the importance of the internal obliques for the walking and running gait. Here’s a tidbit:

If you don’t own your obliques, you don’t own walking. If you don’t own walking, you don’t own movement. If you don’t own movement, you don’t own your spine. It’s that simple.

When the gluteus maximus (butt) muscle isn’t working well, the internal obliques sometimes take over the task of extending the hip. This compensation pattern can devolve into a series of other musculoskeletal problems. The article makes some key observations:

  • Since the internal obliques (quadratus lumborum) control the deceleration of the spine’s rotation, they are instrumental in maintaining spine stability and avoiding injury.
  • One of the hallmarks of oblique weakness is that people stop breathing when performing simple movement patterns to maintain stability. (This makes it essential for runners to focus on oblique function; incorrect breathing patterns and/or an inability to change them may be rooted in oblique weakness).
  • Because spine rotation is essential for gait, improperly-functioning obliques will impair the production and absorption of mechanical energy.

It’s always important to remember that a particular dysfunction has repercussions all over. Oblique functioning isn’t just about spine stability or just about breathing, or just about production and absorption of energy. A dysfunction in any one system has repercussions on many levels in a dynamic system like the body.

Biomechanic Issues, Thinking in Systems

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

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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.

Biomechanic Issues

A functional argument in favor of midfoot striking: putting the research in context.

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The human body is a machine with particular characteristics. So is a car. Just like the many different makes and models of cars have slightly different capabilities, human bodies are all different.

But they are not that different. For example, the operational requirements for all cars are very similar: the centrifugal force generated during a turn must not exceed the friction generated by the tires. And they are the same in humans.

But that’s not the way in which much of the medical and sports science literature treats it. Don’t get me wrong: everybody is in agreement on what the individual parts do: the gluteus maximus abducts and extends the hip; the gastrocnemius points the foot, etc. But there is a vast amount of disagreement as to how these parts are supposed to work together. Rather, there seems to be quite a bit of agreement that for the same systemic function (running), the individual parts can be performing wildly varying functions, and yet the system will still be somehow performing correctly.

I am, of course, talking about the footstrike debate. Before I continue, let me be clear that by “heel-striking” I don’t refer to how the foot hits the ground. I refer to the set of gait characteristics that contribute to overstriding by reaching forwards with the leg and striking the ground heel-first. The same goes with the gait characteristics associated with midfoot striking.

I’ve been reading a series of articles that associate different patterns of loading with different stride types. For example, a heel-strike is typically associated with increased loading of the knee, while a forefoot or midfoot strike is typically associated with an increased loading of the ankle and achilles tendon.

Most of the articles that I’ve read tend to conclude that therefore, we should see greater knee injury rates for heel-strikers, and greater achilles injury rates for forefoot/midfoot strikers.

However, that’s a hypothesis. By this I mean that thus far I’ve found no studies that have shown that these hypothesized injury rates actually occur.

The question is this: are all tissues equally amenable to loading? In principle, absolutely not. Buildings often have central support structures to carry the load. So does the body. The question is whether, say, the presence of the achilles tendon—a dense, springy structure capable of storing massive amounts of potential energy (also the largest tendon in the body)—makes the ankle more amenable to loading than the knee.

In principle, it makes sense that the presence of the achilles allows the ankle to be loaded more than the knee. However, this remains to be ascertained by future studies.

For now, what we can say is that the differences in loading associated with one foot-strike pattern aren’t “equal” to another. Because certain structures are paradigmatically employed by the body to support weight, absorb shock, and store potential energy, a foot-strike pattern that offsets loading to these structures will, in general, be more amenable to the overall health and functional performance of the body. Whether experimental research ascertains that the achilles tendon is such a structure remains to be seen.

However, I certainly agree with the general supposition that a stride type that places more emphasis on loading of the achilles tendon (such as midfoot striking) generates a higher incidence of injury for that structure. Across a population, use of a particular structure will almost necessarily correspond to an increase in injury and overuse rates of that structure.

It remains to be experimentally ascertained whether a stride type which offsets loading onto dynamic structures (muscles) and energy storage structures (tendons and fascia), will, across a population of individuals, create lower overall injury rates despite the likely increase in injury rates due to simple use of those structures.

However, we can still make a systemic analysis.

Let’s use the example of an airplane as an analogy: it is much more efficient for an airplane to use flaps, than to not use them. By increasing the total wing surface, flaps allow landing and takeoff velocity to decrease by a significant amount. An increased use of flaps will no doubt mean that, overall, more flaps will become damaged and broken than if flaps weren’t used at all. But because flaps help reduce the speed at which the aircraft lands, using them contributes to a decrease overall structural stress and damage associated with the impact of landing.

You could even make the argument against using flaps by saying that increasing the wing’s surface area will put more stress on the wing housing and the airplane’s airframe. Even though this is the case, making this argument misses the point. The point of the airframe—and especially of the wing structure—is to absorb the increased stresses associated with increasing the wing surface. Flaps should be used during landing regardless of the fact that both stresses to the wing and incidences of damage to the flaps will increase.

Along similar lines, if we posit that a certain body structure has a certain function, such as the achilles as a structure to store mechanical energy, the gluteus maximus as the main driver of hip extension, etc., then, under optimal conditions, the body should preferentially load the achilles upon landing and put the burden of moving the leg on the gluteus maximus. (All of which seems to agree with the findings of this study):

“When compared to RFS (rearfoot strike) running, FFS (forefoot strike) and BF (barefoot) running conditions both resulted in reduction of total lower extremity (leg) power absorption particularly at the knee and a shift in power absorption from the knee to the ankle.”

All of this said, the systemic analysis of the body is simple: in systems thinking, you look at the functions of different parts, in relation to the whole, to ascertain their function. The achilles tendon seems to be primarily a shock absorber. It certainly works that way when jumping—that’s why it’s almost impossible to land on your heels when you’re jumping straight up and down. So, any stride type that uses the achilles tendon as a shock absorber will likely be more amenable to the body.

Until evidence otherwise settles the matter—and only until then—the most reasonable conclusion to make is that a stride type that uses load-bearing structures to carry weight, offsets torque (rotational force) to joints that can rotate dynamically, uses shock-absorbing structures to absorb shock, and employs energy-return structures to return energy, are “better” than stride types that do not. Given the evidence currently in the literature, everything seems to point to (but not prove) the idea that midfoot striking is an example of the former, and heel-striking is an example of the latter.

AN IMPORTANT CAVEAT: The body is a dynamic system, which means that you can think of it this way this way: if you change one thing, such at the angle at which your foot touches the ground, three other things will change along with it. Perhaps you’ll see a change in your forward lean, a change in your hip extension moment, and therefore a change in the loading of a variety of muscles. In other words, you can never change only one thing. If you oversimplify your understanding or implementation of the changes you need to make in order to be faster, more efficient, or less prone to injury, you will end up being slower, less efficient, and more prone to injury.

This is why it’s important to talk about forefoot striking, midfoot striking and heel striking as “types of gait” and not as “types of footstrike:” the angle at which the foot hits influences (and is influenced by) a variety of other factors. My contention (which I believe is also the contention of proponents of midfoot striking) is that for a supermajority of people, the resolution of all of the biomechanic factors surrounding injury, muscle imbalance, power leaks, and resolvable musculoskeletal asymmetries, will result in the adoption of a midfoot/forefoot strike.

Again, whether this is actually the case has not been borne out by research.

I’d love to read what you have to say about this. Please put your comments, criticisms, and questions in the comments.