Category Archives: Biomechanic Issues

Biomechanic Issues

Why cadence matters.

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A significant debate in the running world today concerns cadence. The question is: At which cadence should a person run? Some argue that the minimum cadence should be 180 steps per minute (spm), on the grounds that it is far more efficient than slower cadences.

Several important counterarguments have been made to this claim. One is that high cadences occur more often in elite runners, and then only during races (and that these same elite runners run at very low cadences during their warm-ups).

In this sense, nobody has ever run at one cadence—and indeed, there simply cannot be a “minimum” cadence: every run that anyone has ever run started out at a cadence of zero (when they were standing still) and their cadence slowly or quickly climbed to the cadence that they adopt habitually at a cruising speed. So, in “reality,” everyone has an infinite number of cadences at which they run: They start from a cold zero steps per minute, and pass through 0.0001 spm, 0.0002 spm, and so on, as they make their way past their habitual “cruise” cadence, up to their personal maximum.

The people who first prescribed a “running” cadence, when pressed on the issue of whether there is “one” running cadence, would almost certainly agree that people go through an infinite progression of cadences during either acceleration or warm-up. They would probably say that they didn’t mean that 180 spm was the sole cadence at which people should run (which is clearly impossible), but rather that 180 spm is the paradigmatic cadence of the human body—the cadence that these elite athletes warm up to (or should, if they don’t), in order to get the most out of their run.

(To be honest, I don’t know the rationale for 180 spm in particular as the cadence of choice—instead of say, 182 or 178 spm. I haven’t read anything about muscular dynamics that suggest that 180 spm is the optimum (or why it is). My belief is that the optimum would be somewhat dependent on the individual’s dimensions. I But it’s very clear that across individuals, 180 spm is a much more efficient cadence than 150 spm, for example.)

By this argument, why do high cadences show up the most in races? Because that’s when efficiency matters the most.

Think of this in the same way we describe “being awake.” We understand it to include a certain degree of alertness. We go through a spectrum of wakefulness from the point that we initially open our eyes and brush off the cobwebs to the point where we can be at the top of our game in a networking event.

It behooves us to define “full wakefulness” not at the point where we are not asleep, but rather, at the point where all the possible systems that contribute to alertness and cognitive function are up and running. If you can “get awake” but can’t brush off the cobwebs—implying that you can’t bring critical cognitive systems into play (or into play enough)—you’ve got a real problem.

Running works similarly. The main argument is that because these physiological systems create a higher degree of efficiency by producing a high cadence, it behooves us to understand “running” as including a high degree of activity of these physiological systems. (In these terms, “running-like movements” can occur at all cadences, but “running” occurs only at the full activation of these systems.)

Cadence increases efficiency because of its impact in a crucial neuromuscular process known as the Stretch-Shortening Cycle (SSC). When the foot lands, muscles all across the body are passively stretched. Then the muscles contract (or shorten) almost immediately, releasing the energy stored during stretching. This helps the leg recoil and be recycled into the next step.

The longer the interval between the initial stretching and the subsequent shortening, the more energy becomes dissipated in the form of heat. The longer the wait, the less mechanical energy available in the muscles and tendons at the moment of shortening.

At a low cadence, the interval between the stretch and the shortening is very long, meaning that a lot of energy is lost as heat (and efficiency drops). But as cadence increases, the interval shortens to the point that very little energy is lost (and efficiency rises).

I often write about how a new capability gives you twice the benefits you expect: For example, because of the improvement in efficiency that comes with a higher cadence, someone that runs a given distance more quickly is not only faster, but it takes them less energy to run the same distance. So the physiological improvements of proper training contribute to produce a much wider set of advantages.

The above shows yet more benefits: The energy that goes into stretching a muscle has to go somewhere: it can either get returned as elastic energy, or it can dissipate as heat. See the problem?

Even though I’m not aware of a lot of research on the conversion of elastic energy to heat, we can say this: the person with a longer stretch-shortening interval—who loses more stored mechanical energy as heat—has two problems, not one: As we discussed above, they have a lower energy return. But also, the additional heat creates a greater thermoregulatory load on the body.

So the runner with the faster cadence (usually the fitter and more skilled one) will not only be more efficient than the runner with the slower cadence, but they’ll also stay cooler. (And to top it all off, the fitter one is probably also the one with more developed cooling capabilities).

Just to be clear: if you’re fit and skillful, you’re also faster, more efficient, stay cooler and can cool down better, but if you’re less fit and unskilled, you’re also slower, less efficient, you get hotter and you’re not as good at getting rid of that heat.

Of course, none of this changes the fact that there is a curve that shows that people do in fact run at lower cadences at lower speeds, and at higher cadences at higher speeds. And it makes sense why they would: despite its benefits to efficiency, you don’t need a high cadence at a low speed. However, sticking to this descriptive reality of the world isn’t very helpful: the problem is that cadence has been shown to correlate more with absolute speed than with relative speed. This generally means that a relatively slow runner going close to their maximum speed will have a much slower cadence than a relatively fast runner going close to their maximum speed.

If we just go by the observed speed-cadence relationship (and let that iterate itself in every runner), the faster runner will always be more efficient. In other words, slower runners won’t get the chance to be efficient.

Good coaches try to get slower runners to run at a fast cadence to allow them to achieve a greater degree of efficiency (although the faster runner may have more overall efficiency due to other advantages). And by forgetting about speed (at least initially) and focusing on increasing cadence, it’s possible to accomplish exactly that.

Biomechanic Issues

Synthetic perspectives on the running human body: Improving running economy is not the be-all, end-all.

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Looking at the body from a synthetic perspective is a lot like looking at it from an evolutionary perspective.

As I described in a previous post, a “synthetic account” of the body—there is no such thing as a “synthetic analysis”—is one that looks at the human animal in its whole context in order to understand why it does what it does, (and what it is attempting to do).

A few theories have a strong synthetic component: Pose Method (which looks at the mechanics of the body in the context of the Earth’s gravitational field), Tim Noakes’ Central Governor Theory as well as his discussion on thirst and hydration, and Phil Maffetone’s MAF Method (which observes that prolonged athletic achievement cannot be produced without safeguarding and promoting the body’s health).

But most accounts of athletic performance out there look at the human body in a very narrow analytic sense. They typically only measure a few variables germane to athletic performance: running economy (also known as efficiency), speed, power, endurance, etc. In other words, they look at the body in the same way you might look at a race car: you analyze how the race car functions and how it performs while on the track. But you don’t worry very much about what it’s doing or what’s happening to it elsewhere.

In this vein, it is often argued that one running form (one particular set of kinematics) is better or more advantageous than another on the grounds that it is more efficient. Take a look at the title of these articles: A Novel Running Mechanic’s Class Changes Kinematics but not Running Economy, and Effect of a global alteration of running technique on kinematics and economy. 

The body has to worry about a number of things beyond running economy: it has to save itself for future battles, quickly rest and recover in order to fulfill any number of foreseen and unforeseen functions beyond the scope of the athletic event, like for example to be unstressed enough to be able to engage smoothly and creatively with social environments.

So, when sports scientists come along and suggest that the best form for a particular athletic movement is what’s most efficient (in the sense of minimizing energy expenditure during the athletic event), they are ignoring some of the body’s broader imperatives.

Why? The simple answer is that the body’s lifelong goal of protecting itself is far more important to it than the very bounded goal of winning some particular athletic event (or chasing down some particular deer) at any cost. It doesn’t just want to get the deer. It wants to benefit from having gotten it.

What does this mean? That benefiting from getting a deer means that it might be better to wait until a slower deer comes by. Let’s suppose you don’t have enough energy to run at the speed and distance you’ll need if you want to catch the deer you want, and still be able to run with the form necessary to protect your body while doing so. You might end up catching the deer, but you might also end up with a blown knee or a damaged achilles. You might be put out of commission for a month or two.

Now let’s suppose that someone else uses a slightly more expensive form—expending more energy to maintain proper movement. They’ll be proportionally slower, but they’ll also be able to move much more and recover much faster. Over time, they’ll become the more powerful runners. Three or four years down the line, they’ll be catching much faster deer, much more consistently.

Of course, it’s important to be as efficient as possible: refining the way muscles work, and aligning them to work with gravity and impact forces (and not against them). But pursuing efficiency is not at all convenient past the point where the only way to get more efficient is to risk tearing tendons, degrading cartilage and connective tissue, and abrading bone.

This brings up another important point: while the safest form has a high degree of efficiency, the checks and balances necessary to produce it (and maintain it at high speeds or over many miles) also means that it is typically more expensive to produce than the “most efficient” form.

 Let’s say that the runner who blew his knee by going after the very fast deer has form X. Form Y might be more expensive, but it would also allow him to get faster over time. But let’s say that instead of getting injured by going faster, he decides to only chase the slowest deer, or run exclusively for fun. He might display the same injury rates as runner Y. But if we only look at injury rates without looking at speed, or running economy without looking at speed, or efficiency without looking at performance improvement over time, we might end up concluding that the wrong ways of doing things are actually better (or worse, that there is no “best” way of doing something).

Being faster (or fast for longer) is great. But that’s not good enough either. The same things that we said about efficiency can also be said about speed. Running with the form that lets you be fast safely, recover quickly, and improve consistently, is waaay better than “just running fast.”

Biomechanic Issues, Defining our Terms

The role of downforce in forward motion.

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There are two main camps in the argument of exactly how we manage to move forward as we run. The traditional camp says that the body uses the muscles to “push against the ground.” The other—constituted almost solely by Dr. Nicholas Romanov’s Pose Method—proposes that we move forward thanks to the action of gravity on our bodies.

This second camp suggests that what the muscles do—their primary function—is to convert the downward force of gravity into net forward movement.

But how is it possible that the body can convert a downward force into horizontal movement?

Part of the answer lies in the fact that the running movement isn’t really horizontal. It consists of a wave-like movement of the hips and torso—an oscillation—that only seems to be a straight line if we’ve zoomed out far enough. If your model (incorrectly) assumes that the body is trying to convert a downward force into a force that travels on a horizontal linear vector, you’ll end up quite confused.

(But that’s a discussion for a different post.)

Let’s get to the issue I want to talk about: Proponents of the idea that runners “push off” often understand Dr. Romanov’s argument—that gravity is the “driving force”—as claiming that gravity provides “free” or “additional” energy (a.k.a. net energy) if we adopt a certain technique.

I believe that’s a rather shallow misrepresentation of what Dr. Romanov’s Pose Method has  actually suggested. Pose’s main message regarding the action of gravity in running is quite a bit more profound. To explain why this is—and what I believe the main message of Pose is—let’s abstract away from mentions of “gravity” for a second and talk about a more general concept: downforce.

Instead of runners, let’s look at race cars. What are the necessary factors in making them go?

First and foremost, a race car needs a powerful engine. Without an engine, it’s going nowhere. But an engine is not enough. As any connoisseur of modern racing will tell you, there came a point in the evolution of car racing in which the engine’s ability to turn the wheels exceeded the ability of the best tires to grip the best track.

Why? Engine power eventually exceeded the car’s weight (defined as “how much force is generated as gravity accelerates its mass towards the ground”), and the capacity of the tires and the track to covert that weight into friction.

This reveals an important truth about the car: the engine actually isn’t for moving the car forward. The function of the engine is to spin the wheels. (While this results in driving the car forward, actual forward motion only occurs insofar as the power with which the engine spins the wheels coincides with the extent to which gravity keeps the car on the track.)

At this point, the only way to achieve greater speed was for engineers to somehow find a way to add to the downward force that gravity exerts on the car. How did they solve this dilemma? By adding the ugly inverted wings we now see on the back of every Formula 1 and drag racer: spoilers.

By redirecting the flow of air upwards at the tail end of the car, spoilers create another significant downforce. This reveals that strictly speaking, it isn’t gravity that allows race cars to move forward. It’s downforce. (Gravity just happens to be the quintessential downforce on Earth.)  But the point is this: no downforce, no movement.

Let me spell out the implications in the strongest possible terms. Muscle power is NOT the driving force. It is the intermediary force. It converts a downforce into a quasi-horizontal oscillation. The driving force—the thing that ends up as movement—is gravity. Muscle power (a.k.a. metabolic energy expenditure through muscle use) is what lets gravity end up as movement. Gravity could provide zero net energy (zip, nada) and still it makes sense to call it the “driving force.”

The important question to ask about running isn’t really whether one running technique “uses” gravity to run—all running necessarily does so. Let me be even more specific: all overground movement is a result of expending energy in order to convert some downforce into a quasi-horizontal movement. The degree to which movement occurs is commensurate to the degree to which the organism/machine is harnessing downforce in real time.

Running according to the tenets of The Pose Method gets you “free energy” from gravity in the same sense that a car that never fishtails also gets “free energy.” In other words, Pose offers the cheapest way, all things considered—speed, agility, endurance, resilience, performance consistency, performance frequency, metabolic flexibility, recovery, longevity, etc.—to convert as much downforce as possible into overground movement. The critical observation offered by The Pose Method, then, is about how the body’s “engine”—its musculature and various systems—work best to harness the force of gravity to produce forward motion.

If the car weighs too much for the engine, it stays put. If engine power exceeds grip, it spins out. In other words, car’s absolute theoretical speed limit on Earth isn’t set by the power of the engine, the design and engineering of the transmission, or the materials it’s composed of. The maximum horizontal speed that any object can achieve is set by the theoretical limit to which it can harness the few downforces available to it on Earth. Once the car’s power and engineering causes it to reach speeds at which it is impossible to stop the air around it from supercavitating (creating a vacuum around the skin of the car), no aero kit will allow it to go faster, and no further improvements to the drivetrain will do it any good.

Of course, unlike race cars, the human body is not set up to use wind as a downforce—and we couldn’t run fast enough to make it matter anyway. Our running speed is a function of our ability to harness one downforce: gravity.

For a runner, improving efficiency by harnessing the force of gravity can mean 2 things:

  1. Removing power leaks and other muscle use that does not contribute to harnessing gravity. (The race car example would be to swap in better and better parts, and to make sure that you don’t throttle up enough to drift the car).
  2. Increasing top running speed: a runner with good form (a.k.a a runner whose movements and stances maximize the harnessing of downforce) can do so to a greater degree—in other words go faster—than an identical runner whose movements and postures do not effectively harness downforce.

Note that #2 is a hidden efficiency: it only reveals itself insofar as the runner goes faster. Both the inefficient runner and the efficient runner may be using a very similar amount of energy at lower speeds, but only the more efficient runner can get to a faster speed.

Pit my Toyota Tacoma against a Ferrari. Both would perform quite similarly at lower speeds and wide turning radii. If you ask both of us to make a wide sweeping turn at 60 miles an hour, we’d perform almost identically. You’d say “Whoa! Correcting for weight, they’re equally as efficient!”

But this observation only holds at lower speeds. If you increase the speed to 160 mph and tighten the curve, my Tacoma would start to spin out or come off the track, forcing me to reduce my speed. In other words, even if you doubled the horsepower on my Tacoma, I wouldn’t be able to match the Ferrari because of its stiffer suspension, better tires, lower profile, and aerodynamic design (in other words, it’s much better at harnessing downforce).

I believe that the discussion of “saving energy through the use of gravity” is meant to help us recognize—for starters—that we move forward only to the degree that friction and muscle power meet. It also has a few other implications (to put it mildly), but those are best left for another post.

 

 

UPDATE: Check out what I’ve written on The Pose Method:

About Pose theory of movement in running.

About Pose theory of movement in all sports.

About the “unweighing” principle of Pose theory.

Biomechanic Issues, Principles of Training

The Running gait, Part 2: Movement logic and The Pose Method

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It seems to me that nobody can quite agree on exactly what is happening during the running gait.

The running gait is characterized by an alternation of support: at one point, your body is supported on the ground by your left leg, then you’re suspended in the air, and then it’s supported by your right leg (and then subsequently back to your left leg). It’s how you get from these support phases—also called “stance phases”—to being suspended (and back again) that people vehemently disagree on.

Many in the running community say that the motive force of running is produced by a strong push of the leg muscles against the ground. But Dr. Nicholas Romanov of The Pose Method suggests a different—and in my opinion, far more parsimonious—interpretation of what happens: instead of “pushing,” the body accelerates its center of gravity by repositioning itself relative to the point of support (the foot on the ground).

UPDATE # 1: All repositioning occurs due to muscle activity, and the speed and effectiveness with which the body (or a specific body part) can reposition is commensurate to the power of the relevant muscles.

We typically think of “acceleration” as “the thing that makes cars go from 0 to 60.” But even a slight weight shift is an acceleration. When the slowest snail takes one tiny step, it’s accelerating it’s body (and then promptly decelerating it). Similarly, a slight weight shift constitutes an acceleration of the part of the body that moved. A greater weight shift is an even bigger acceleration. If you string together enough tiny weight shifts (or big ones) in a close enough sequence, you get a really big acceleration!

In this post, I’ll argue that the most logical way of producing a human movement (and that of any segmented organism) is by shifting the most easily-movable part first.

If you look at the body from a design perspective, you’ll see that it’s a stack of different parts (feet, calves, thighs, hips, etc.), all separated by joints. In the standing posture, each of these parts provides support for the part above it, much like a stack of bricks. But the difference is that the body’s joints let each brick move semi-independently of all the other bricks. The question, then, isn’t “how do we run?” It’s waaay more basic than that. The question is: to get from A to B (over and over again), how does a stack of things have to move?bricks.jpg

You could simply lift the bottom brick—along with all the bricks on top of it—and move it that way. That’s not particularly convenient, though: it requires a lot of energy in very little time. But there’s another way: start from the top brick. That way you only have to move one brick at a time, shifting bricks in quick succession.

This is the logic that your body (and the body of any segmented organism) uses to move. If you’re standing on two feet and want to lift your left foot, you don’t start by lifting your foot. You start by shifting your weight—starting by your shoulders, and moving down the body—onto your right leg, effectively removing all the weight off your left foot.

(This takes all the top “bricks” off the foot first.)

I’ve just described to you a process intrinsic to any human movement, which Dr. Romanov calls unweighing. This is the simplest process: if you want to move a limb, you first shift all the weight you can off it first, and then you move that limb. What makes Dr. Romanov’s theory parsimonious is that you need very few ideas to successfully describe human movement as a whole. Case in point: the movement of the entire body is simply a large-scale version of unweighing.

If you want to move, you create a forward weight shift in the direction you want to go. This effectively takes your weight off your feet and puts it in the space ahead of you.

Let’s talk running. During stance, one leg has the entire “stack of bricks” on top of it, and the other one is suspended in air (and already traveling forward), with nothing pulling it to the ground but its own weight. (UPDATE #2: In terminal swing, that leg actively reaches for the ground in order to provide new support). But when one leg is in early stance and midstance, which do you move? Do you push with the leg that has all the bricks on top of it, or do you move the foot with nothing holding it in place—the “topmost” brick?Running bricks

That’s the question Dr. Romanov answers with the Pull. The Pull describes the process of getting the back leg off the ground, and recycling it forward to produce the next step. But part of the hidden importance of the Pull is that it is also a weight shift: whereas in the previous weight shift you drifted your shoulders a few inches to one side, in the Pull, you aid the elastic recoil of your tendons in pulling your foot from the ground. This brings the mass of your entire leg ahead of the foot currently supporting you on the ground.

Galen Mo
Like this, but not as effectively (and with far less flair).

In a proper landing, your foot will touch the ground just ahead of your hips, torso, and head. There’s a slight deceleration due to the foot’s contact with the ground, but the body as a whole continues to travel forward, vaulting over the support leg. If the leg that just came off the ground—the “Pull” leg—moves forward fast enough, the body can add more of its mass ahead of the point of support.

We already know that a small weight shift—drifting the shoulder to one side—causes you to move (read: accelerate) slightly to that side. Now imagine how much more acceleration you can create by pulling the leg and moving its mass ahead of the body.

Mainstream thought questions whether this kind of weight shift can create enough momentum to offset wind resistance, plus the braking effect of landing, plus any power leaks that the person might have. The argument goes that if it can’t, the “pushing” argument is more likely the correct one.

But I hope I’ve convinced you that the best way to move a stack of things is by moving one part at a time in order to tip the stack in the direction you want (and then continue to move the parts in order to create more acceleration). Supposing that this—the best way to move a stack of things—somehow wasn’t enough to overcome wind resistance and the braking effect of landing, there’s no way that you could do it with pushing (a.k.a. moving from the bottom brick) because, well, it isn’t as effective.

So if the question of running is “what is the best way to offset wind resistance and braking?” the answer would still be to reposition the most easily movable limb in order to create a weight shift to move the body in the desired direction.

Read my initial take on the Pose Method here, and how the Pose Method applies to all other sports here.

Biomechanic Issues, Uncategorized

The Running Gait, Part 1: Contralaterality

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All gait is a contralateral movement. Although It seems like the most obvious statement (perhaps to the point of being boring), it often astonishes me just how unexamined it remains. Discussing both the theoretical and practical implications—what it means for our training—is what this series of posts is all about.

To say that a movement is contralateral is to say that when something happens in one side, the opposite will happen in the other side. During gait, if our left leg moves forward, our right leg moves back. But our gait is also reciprocal, meaning that the limbs in the same side move in opposition to each other, to balance their movement. If our right leg, supporting our body during the stance phase of gait, moves back, our right arm swings forward in a passive motion meant to balance out this movement.

This kind of reciprocal action is very similar to the kind of activity that you find in a lot of modern machines. Let’s take the internal combustion engine as an example. To make this simple, let’s look at a flat twin engine like the one mounted on a lot of BMW motorcycles:

Boxerengineanimation

In the image you can see two pistons, each moving in opposition to each other around a crankshaft. This movement is—or should be—a lot like the movement of the legs around the hips. By the way, this imagery isn’t just a metaphor: there are important similarities between the mechanics of the piston system and the mechanics of the hips and legs.

I liken the lowest point in the piston’s rotation to when the leg (the right) is in swing (1). The apex of the piston’s upswing corresponds to midstance, where one leg (the right) is fully supporting the body (2). At the same moment, an opposing piston must be in the lowest point of its downswing in order to balance the mechanism.

Piston Mo
By Zephyris – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10896588

Any problems in the balance of the pistons or the crankshaft can cause something to go horribly wrong. The same goes for the body, in order for its movement to be in balance. As the left leg clears the ground behind the body, the right (opposite) arm must be ready to initiate the upswing. And the right leg should be ready to start reaching for the ground below.

Insofar this is the case, the movement can be said to be contralateral.

Let’s look at the pictures of Mo again (taken as he is sprinting down the final stretch of his gold-medal performance in the 10,000 meter event of the 2012 Olympics). As you can see from the right arm in (1) and the left arm in (2), both pictures are taken at the same moment in gait (from the frame of reference of the arms).

MO Mo

By comparing both pictures you can see a bit more flexion in early stance for the left leg (1), than for the right leg (2). At this moment in gait, the right leg trails further behind the body (1) than the left leg. (The left calf (1) is also at a larger angle than the right (2).) Without getting too far into the mechanical details, it would seem that Mo’s having a little bit more trouble stepping forward with the right leg than with the left.

In effect, in picture (1) his left leg is flexed because it’s waiting for the trailing right leg to catch up. And if you look at the orientation of his forearms, you can see that the right elbow (1) is far more flexed than the left (2), mimicking, to almost a perfect degree, the angle of the opposite knee in each of the pictures.

The point is that it wouldn’t matter where you look at the piston system (of an internal combustion engine) from. Whether you observe the piston system from the frame of reference of the piston head, the main axis of the crankshaft, or the counterweights, you would see that the entire system is balanced. Each counterweight remains perfectly opposite to a piston, and the pistons remain perfectly opposite to each other.

This is so important that much of what makes sports cars—particularly “traditional” sports cars like Ferraris—and race cars cost as much as they do is the technology to keep the engine block balanced to the picogram. The better this is accomplished, the more torque can go through the engine without breaking apart the block.

Mo Farah is not some amateur. For the past few years, he has set the highwater mark for excellence in distance running up to the 10,000 meters. And even then there are differences.

Why is this happening? The “big” answer to this question probably isn’t in some esoteric discussion of biomechanics. Quite simply, the 10,000 meters are run on an oval track, and this is the final stretch. For more than 24 laps, he’s been turning into his left leg. It’s probably a lot more tired than his right, so it’s having a harder time supporting his body during stance. (Hence the flexion).

If we asked Mo to keep running for a few more laps (not that he would) we’d find that his right leg would continue to trail a little more, and his left leg would flex even further. If you look at the video you’ll see that even down the final stretch he’s compensating quite well by driving forward with his right shoulder every step.

But as he becomes more tired, we’d see that this strategic compensation stops being enough. We’d probably observe his left foot taking increasingly longer to leave the pronation (flattening) that occurs during the stance phase. The supination (pointing) which occurs towards the end of the stance phase, would come too little, too late, possibly creating a heel whip for the duration of the race.

pronation & supination.png
Pronation and Supination

As this is happening, the huge amount of forces that go into his body as his feet strike the ground will travel through it at increasingly odd angles. There is a potent compounding effect here: The more experienced, fitter, and more rested body aligns itself correctly with the forces of running. The less experienced, less fit, and tired body does not.

For the weekend warrior with the New Year’s resolution, running a marathon is biomechanically a far more hostile experience than it is for the skillful runner. Some people overpronate from the get-go. Others start with a tight hip. Over the course of 40,000 paces, this brings nothing but disaster.

Physics favors the trained runner much like the Greek Gods favored the heroes of mythology, by further increasing their already formidable advantages in battle. The skillful runner already comes into the race with stronger muscles, denser bones, a more resilient nervous system, and a more robust metabolism. As a final reward for their training efforts, the impact forces of running fall into place and work with them, not against.

 

Biomechanic Issues, Principles of Training, The aerobic system

Running form and aerobic training

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Training at a low intensity—often referred as “aerobic training”—is extremely important to allow the body a respite from the stresses of high-intensity training, and to develop the mechanisms that increase its resilience. We know that much.

But when training aerobically is our only focus, even during a period of “aerobic-only” training such as base-building, we may be hindering our improvement: improving our running form, by reducing the difficulty of running, also reduces the stress on our body. Because stress suppresses the function of the aerobic system, taking the time to develop our form hastens our aerobic gains.

The standard set by The Pose Method is the best example of “good running form,” as I see it. I fully adhere to the notion that pursuing a standard—the right standard—of running form is the quickest and surest way to reduce the difficulty and stress of running. But I also believe we don’t need to go as far as mastering the tenets of The Pose Method to reduce stresses and bolster our aerobic training.

This is because of a concept called “power leaks.” Running is all about moving the center mass of the body forward in a straight line. Some vertical and horizontal oscillation can’t be gotten away from. However, minimizing that up-down and side-to-side movement lets more of the body’s energy to go towards moving it in a straight line, and removes the need to spend energy balancing the body’s odd movements.

Power leaks, in essence, are those jerky movements that happen in odd places of the body—a sharp outward rotation of the knee combined with an upward collapse of the hip, which causes the weight of the body to fall to the outside. The body then has to recover, shifting its weight back in, to produce the next step.

When this extraneous weight shift and joint movement happens, the force of the footstrike travels through the body at an odd angle. Muscle fibers, and tendon and bone tissue are meant to move in alignment with the major force the body experiences: gravity, which pushes the weight of the body downward, and the opposite and equal ground reaction force the body experiences when the feet are on the ground. When tissue does not align with force, the likelihood of injury skyrockets.

“Stress.” is the body feeling that its likelihood of injury increases. Therefore, its defense mechanisms kick in. As a result, it does one of two things:

  1. It slows the body down in order to mitigate those forces to a comfortable level.
  2. It kicks up the stress response (and the heart rate), because it remains in a situation where there is a dangerous challenge to its physical integrity.

The increase in heart rate (and decrease in speed) is commensurate to the magnitude of the challenge.

Here’s the big lesson: if you want to reduce the body’s stress response to a particular task, increase its skill level.

Of course, there are myriad other stresses that conspire to wreck the body’s aerobic function: environmental, nutritional, even social. But the physical stress of poor alignment, due to the lack of skill required for the task, may be the larger part of the equation.

Running is an exceedingly complex task, biomechanically speaking, and it is performed by a full-fledged, multifaceted human, with imperfections and worries and commitments. Very few people have the privilege to be monks. Very few people have the privilege to increase their sleep, move far away from the chemicals endemic to the urban sphere, and detach themselves from the social preoccupations that come from being social animals.

But every one of us who has the time to run also has the time to perfect our running form. The problem is that few of us are aware that running form can be perfected, and that it is a way to reduce the stress of running. Misalignment is a real thing.

Alignment, or a lack of it, determines whether three astronauts get to return to Earth (or not). It determines whether our knees and hips survive the gauntlet of a hundred thousand steps we take during the marathon. It determines whether the body feels relaxed and competent when it analyzes its capability of performing a task.

“Aerobic training” isn’t the only way to approach the functionality of the aerobic system. Improving our form can do that too.

Biomechanic Issues, Thinking in Systems, Training Ideas

Shoulder (T-Spine) training for runners: Completely overlooked, and absolutely necessary.

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The benefits of lower-body training have always been obvious for runners. For the past few years, we’ve seen that the ill-defined and ill-understood “core” has come into its own as a legitimate focus of attention for runners who want to better their athletic situation.

The shoulders are just as important as the core—and yet almost completely neglected.

Most of us who are a little bit studied in the science of running know that arm swing is largely passive—a way for the body to contralaterally balance the movement of the legs. So why should we even worry about the shoulders?

We should care because of how they are connected to the body and how they affect the areas around them. The shoulder region is also known as the “T-Spine”—the T-shaped structure created by the backbone, the shoulder blades, and the collarbone (and of course, the hugely complex array of muscles, tendons, and ligaments that contribute to its function).

If any one of the muscles implicated in T-spine function is impaired, functionality of the entire structure goes down the drain.

scap-muscles

Developing T-Spine functionality is important not only because the shoulders and arms are part of the body (and are needed for running well) but because in that immediate vicinity is the ribcage—and the ribcage houses the lungs and the heart, which are the main facilitators of the aerobic system (a.k.a. the distance runner’s main engine).

Bad T-spine function isn’t isolated to runners—it’s one of the biggest motor problems in the general population. In this sedentary world, our brains never had to understand how to use this complex (yet astonishingly elegant) interface between the arms and the torso.

Think about what happens when someone has bad general stability (they are “klutzy”), and their stability is challenged by walking on a balance beam or a raised log: they tense up and are unable to complete the task—or alternately, grossly underperform relative to someone with better motor control.

The same thing happens to the T-spine, particularly in a dynamic, repetitive-impact sport such as running. (Imagine, if you will, the same log or balance beam shaking repeatedly).

When faced with this kind of challenge, any impairment in function causes the T-Spine to seize up and refuse to move.The arms stop being able to swing freely. The “natural” arc that the arms would follow passively (if there was total freedom of movement) gets altered. Because the arm swing directly counterbalances the movement of the legs, either the legs move differently to match the different arm-swing, or the movement of the body stops being in sync with the forces traveling through it.

As is the case with Mr. Shutterstock here.

These are the building blocks for a running injury. (But it gets worse).

Since the shoulder blades sit on top of the ribcage (and the rest of the T-spine mechanism is literally all around it), the ability of the ribcage to expand and contract is immediately impaired. The diaphragm must work harder to make the lungs expand. Less oxygen permeates the body (with more effort), resulting is less aerobic development. In the long-term, improvement stagnates.

A mechanical problem can have far-reaching consequences: it can (indirectly) impair the body’s ability to utilize energy.

Or it can force a hopeful distance runner to think that they “aren’t made for endurance.”

The problem becomes exacerbated for broader-shouldered runners (like me) who lose upper-body mass due to the natural emphasis running places on the lower body system. These runners have comparatively more bone mass up top, which means that they need comparatively more muscle mass in order to keep that heavier structure mobile and stable.

When the T-Spine is neglected, muscle strength may drop to the point that it takes a lot more effort to keep this structure stable. Adding distance (or increasing power) may cause the weakened structure to seize up.

A seeming conflict of interest arises here: stockier runners have an increased need to lose weight to improve running economy. Keeping the muscle mass necessary to stabilize the T-Spine may mean that they won’t be as fast, at least in the short term.

The thing is, it’ll open up oceans of future potential. Usually, the main bottleneck for the development of a distance runner isn’t their weight. As Gray Cook said in a recent interview on T-Nation, “Technique is always the bottleneck of limitation.” This is true even when applied to something as basic as T-spine mobility. If the body—or a part of it—can’t move right, that athlete is never going to fulfill their potential.

T-Spine function is not the only problem plaguing runners. But how many runners may be plateauing because of this—and don’t know it?

UPDATE: While we can’t pinpoint the origin of Mr. Shutterstock’s problem from a picture—the problem may originate in the pelvis, for example—it is plainly evident that the shoulders, arms, and the entire T-Spine isn’t moving correctly.

UPDATE 10/22/15: Matt Whitehead from Oregon Exercise Therapy shared an excellent article about many of the specific postural imbalances associated with T-Spine dysfunction. He makes a great point about the “dos” and “don’ts” for correcting these kinds of problems: “[Nike athlete Mary Cain’s] coach can drill her over and over about swinging her arms straight forward and back, but it just won’t happen until her upper body posture is improved.”

Biomechanic Issues

What is the role of efficiency in athletic performance?

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In various social media, the following observation was made several times about my last post: efficiency plays an important role in athletic performance.

Yes. Efficiency is an essential indicator of athletic performance. However, all efficiencies must be in service of greater power production, not simply sought after without a good reason: efficiency has no real benefit when divorced from other variables.

Here’s a quick but illustrative example: It takes a lot more energy to keep a spine straight, with hips, head, and shoulders evenly stacked, than it does to let that spine develop a pronounced thoracic kyphosis—the spine and shoulder curvature we associate with “bad posture.” Does this consume less energy? Yes. But in doing so, it puts a variety of systems—not just muscles, but even the respiratory system—at a disadvantage.

(Tellingly enough, there’s an important relationship between metabolic and aerobic power and the capability to maintain an upright posture).

Achilles_Statue_in_Corfu_by_MaJr12
Good Posture, brought to you by Achilleus

If we try doing a front squat with bad posture, we’ll set ourselves up for either a plateau or an injury. In effect, we have to resolve this problem by increasing the body’s energy consumption (reducing efficiency) in order to produce the alignment that allows us to correctly perform this movement under load.

Ultimately, however, efficiency is extremely important in sports such as running. This is known as running economy. Elite runners tend to have great running economy, meaning that they use less energy to cover a certain distance.

There are a few ways that running economy can be improved: one is to increase aerobic power. Six times as much energy can be gotten from molecules of glucose that are burned aerobically rather than anaerobically.

Another way is to increase neuromuscular synchronization and power. A knee that collapses in or hip that collapses up during the running stride is known as a “power leak,” meaning that muscles are misaligned and therefore pushing the body up, laterally, or rotationally instead of contributing to driving it forward.

Yet another way to increase running economy is to become smaller. This includes having reduced fat percentage and increased muscle percentage, but it encompasses more than that: runners that are volumetrically smaller have a much easier time traveling distance than runners that are volumetrically larger. Why? If you’re taller, not only will your bones and muscles have to be thicker (in order to retain the same proportions), but then your organs, especially your heart and circulatory system, will be working that much more to pump blood from your toes to your brain.

It doesn’t matter what aspect of running economy you’re talking about. Not only does the economical runner expend less total energy than the non-economical runner, but a greater percentage of total energy expenditure ends up going towards crossing the finish line rather than being lost in vertical, lateral, or torsional oscillation, power leaks, or greater metabolic upkeep.

The question of efficiency or running economy should always be asked in tandem with the question of athletic performance: is seeking some initial efficiency—for example, bowing my upper back because I’m tired—going to hinder my athletic performance or development?

Personally, I believe that “good form” for any athletic activity is “that form which allows us to express greater athletic power.” That’s how it’s defined across martial arts, baseball, the decathlon, and marbles. That should be how we define it in running too.

When a forefoot strike results from all the correct physiological and gait factors, a greater proportion of the stance will be spent on the forefoot, meaning that a greater proportion of the stance phase will go into force production. The stance is shorter overall, and the speed is faster. Is this stride type more costly (and does it produce its own set of injuries)? Maybe, possibly. Sure.

Do certain distances place such a burden on people’s endurance—even that of elite athletes—that they opt out of the “power producing” stride type completely? That’s the billion-dollar question, and given the answer, we might find that it is completely within reason to adopt a hybrid stride or even a heel strike at certain distances, full stop. (Or, you know, we could just walk).

Great form (and great technique) are expenses of energy, both immediate and in terms of time and training. But achieving them will facilitate efficiency at a higher athletic level: we’ll expend more energy, but we’ll be able to apply a greater percentage of that energy towards the achievement of our athletic goals.

Biomechanic Issues

Athletic performance is not about efficiency. It’s about power.

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One of the most oft-used pieces of artillery in the debate of minimalism versus maximalism, forefoot versus hindfoot, and barefoot versus shod, is the discussion of efficiency. Numerous studies have come out that rank the efficiency of these running types against each other, and consistently find that shod/hindfoot/maximalist tends to be more efficient.

(For the record, I think that the first camp that made the efficiency claim was the barefooter/forefooter/minimalist one. For reasons discussed below, that was a bad call).

Anyhow, it’s time to put this discussion to rest: Better athletic performance has never been a function of efficiency, when efficiency is defined as “lower energy consumption for a given speed.”

It has, however, always been a function of increased power output.

Before going into the science of it, let’s discuss how this makes sense from a logical perspective. Time has alwasy been the primary form of currency. A powerful runner can finish a race and begin recovery much more quickly than a slower runner. This frees the powerful runner from the effects of the race much more quickly, and reduces the time that it takes for this person to engage fully with a new task, relative to a less powerful runner traveling the same distance.

The benefits of this are as obvious as they are many, whether we be talking evolutionarily, or in terms of the body’s economy. This also holds when you look at how we define performance across all sports: increased power (and not increased efficiency) begets greater performance. Whether it be during a running race or a baseball game, whoever can apply the most energy effectively in the shortest amount of time towards achieving the goal will come out on top.

(I’ll discuss the deeper implications of this sentence in another post.)

The science corroborates this theory. In Running Science, Owen Anderson is quite clear: “The marathon is a power race.” He discusses at length how the idea of doing long, slow training for what is (presumably) a long, slow race is superficially logical but ultimately flawed. While developing aerobic capacity is immeasurably important for the marathon, as speeds get faster, greater power becomes more and more important.

The importance of power holds even for the ultramarathon. Numerous studies have been done confirming the idea that phyisological indicators of power maximums—peak treadmill velocity and VO2 MAX—correlate strongly with ultramarathon performance.

The sports technique (whether it be running technique, golf technique, swimming technique, etc.) that lends itself to the development of greater power, and not increased efficiency, can be judged to be “better,” given that what makes us universally better at sports is the application of greater power. As this article finds, more runners rise onto their forefoot the faster they go. Landing on the hindfoot is reserved for the slower crowd.

But there may be other, more insidious problems with seeking efficiency in lieu of (or at the cost of) power. In my last article I wrote how, if increasing efficiency is our primary goal, at some point we are going to be sacrificing power—basically engineering our own performance losses.

It’s fine with me that some people genuinely don’t want to seek greater performance, and rather run (or do other sports) for maintenance, rather than increase, of fitness. But this discussion of performance brings up a series of questions that I believe are legitimate: is heel-striking a “running style,” or is it a biomechanical feature—a hallmark—of subcompetitive fitness? Are heel-strikers slower, or does heel-striking make the runner slower (or alternately, become a barrier to improvement)?

I believe that this discussion merits an extensive inquiry into why heel-striking is the form of choice across a majority of runners. Is this the case because more efficient is better? Or is it the case that a majority of runners are lacking in the aerobic, muscular, or metabolic power necessary to sustain a more costly technique—one which constitutes the gateway to greater athletic performance?

These are not rhetorical questions, and they are certainly not answers. However, we treat the literature’s findings in regard to efficiency as if it somehow settles the footstrike debate (or lends evidence either way). It’s time to open the discussion again, and do so by asking questions that are more relevant than efficiency to the human body’s design, as they are to its athletic performance.

Biomechanic Issues, Principles of Training

My reflection on The Pose Method’s principles and processes.

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The supermajority of runners—of people in general—are fond of saying that there is no one way to run. We accept that there are specific techniques for swimming, throwing a ball, swinging a golf club, doing a spin kick, squatting a barbell, and even for properly flipping a goddamn omelet. We accept that adhering to these techniques will make us better at the motion, and less likely to be injured.

(I’ll bet you a hundred bucks that you’ll get carpal tunnel if you flip an omelet wrong one time too many).

But this doesn’t apply to running. When it comes to running, everyone’s different.

Or so they say.

Dr. Nicholas Romanov, founder of The Pose Method, disagrees. After extensive study and experimentation, he identified the key similarities between everyone’s running style. In order for us to be able to run—to move forward consistently without falling—we have to alternate support: one leg remains on the ground, allowing the body to fall forward (instead of downward), while the other moves through the air to create new support under the body’s new location.

The biggest similarity between everyone’s form, whether we’re talking about a couch potato with a New Year’s resolution or about Usain Bolt, is this: at some moment in time, one foot will be supporting the body on the ground, while the other will be passing under the hip area (which is known in biomechanics as the general center of mass, or GCM).

This is what Dr. Romanov refers to as “pose.” How to achieve pose properly is the centerpiece of his method.

Consequently, the most important difference between that couch potato and Bolt—but not the only difference, of course—is that Bolt takes far greater advantage of the time spent in pose.

When we look at Usain Bolt’s running, we recreational runners and non-athletes get the sense that we are looking at genius. We may not be able to put our finger on this genius or break it down with precise words, but we recognize it as genius nevertheless.

But what we are really seeing in Bolt is a perfect running pose—a masterful, yet unconscious (and possibly unknowing) execution of the principles laid out by The Pose Method.

The Pose Method isn’t a “running style.” Dr. Romanov emphasizes this heavily—he didn’t “invent” the running pose any more than the squat and the snatch were invented. These weightlifting forms were discovered: the squat is the best way to lift weight on the shoulders, and the snatch is the best way to propel weight vertically from the ground. The running pose is also a discovery: it is the best way to harness the force of gravity to create horizontal displacement of the upright human body.

The method part of the name refers to a recipe built around the simplest, most efficient exercises that can help us replicate pose effectively and consistently across distance and time.

To truly understand The Pose Method, it’s critical to grasp the role that gravity plays in running. On the surface, it seems that gravity has little benefit beyond helping us return to the ground so that we can once again propel ourselves forward. Gravity is a downforce. We all know this. So how, then, can it help us move horizontally?

Because of the support phase, that is, the running pose itself. When one foot is on the ground, and we shift our center of gravity even slightly forward of that foot, we begin to fall. But we can look at it in a different way: falling forward is really a rotation, at least at first. When we run, the support foot acts as the vertex of an angle between our hips and the direction of gravity. When we’re perfectly upright, that angle is zero. As we shift our weight forward, that angle increases: our hips (along with the rest of our upper body) travel forward, while our support foot remains behind.

Effectively, we’ve converted the downward force of gravity into a rotational force. The greater the angle, the greater the force.

Of course, if we just keep increasing that angle without doing anything else, we’ll fall on our face. But we don’t—our body has all the necessary countermeasures in place: they’re called reflexes. In order to catch ourselves, we reach towards the ground with the other foot.

Ideally, that foot should land directly under the center of mass. This is the case, at least, in Usain Bolt’s running (and that of a few other luminaries, such as Galen Rupp). In most of us, the foot lands somewhere else.

If our foot lands in front of us, momentum has to carry our center of mass forward, until arrives on top of the foot. Only then can we begin to use gravity to advance. And if it takes too long for our heel to lift, we are not falling forward in the earnest—heel lift is a critical component of any athletic movement. That’s why it is so emphasized across sports.

To the degree that our foot lands ahead of us, we are wasting time. And to the degree that our heel delays from lifting, we are losing power.

In order to prevent each of these two issues, the swing leg (which is off the ground) must remain under the center of mass for the entire time that the weight of the body is supported by the other leg. While one forefoot is on the ground, the other foot must remain under the hips.

The array of injuries and problems with the running of most runners are caused by deviations from pose. When we see a master runner—when we recognize genius—we are unconsciously recognizing that these few conditions are being properly satisfied. All other nuances of form are by-products of these few facts.

Dr. Romanov likes to say that we all run in pose. Regardless of our race, creed, gender, or ethnicity, we’ve all gone through this position every step of every run we’ve ever run. What differs between runners is whether we achieve pose—and retain it—effectively.

Whether there is a proper way to run is not a question. Whether there is a way to find it is not a question. The only real question is whether we hold to old, absurd paradigms—that running is the only sport where there is no One Right Way—or whether we engage our time and efforts in mastering principles which have already been discovered and already been presented as the core teachings of The Pose Method of running.