Tag Archives: muscles

In defense of the endurance running hypothesis, part 1: how we think about evolution.

The endurance running hypothesis is the idea that humans evolved primarily as endurance runners. The argument goes that the human physique evolved and took its shape and function from the primary adaptive pressure of persistence huntingthat of chasing down our prey until its body shuts down.

However, this hypothesis is not without its detractors. A significant amount of scientists provide an array of counterevidence to the endurance running hypothesis. (And the debate continues.)

Take for example the case of the human gluteus maximus (butt muscle). Lieberman et. al. (2006) claim that the human gluteus maximus evolved its shape and size due to endurance running.

However, another article in the Journal of Comparative Human Biology finds that the gluteus maximus grows much more in high-force sports (weightlifting) and high-impact sports (such as soccer), than it does in endurance running. In fact, they also show that the butt muscle in endurance runners is no larger than in the non-athlete population.

What I disagree with is their conclusion, which is paraphrased in the “What does this mean?” section in the image below:

“The human gluteus maximus likely did NOT evolve through endurance running, but through varied explosive and forceful activities.”


My disagreements with the article (and the image) are primarily about how and why we interpret the science to mean a certain thing.

At first blush, the fact that endurance running doesn’t enlarge the gluteus maximus as much as other sports seems to detract from the idea that the muscle takes its shape from endurance running. But I think it actually adds to it.

By my analysis, these findings show that the basic, untrained shape and size of the gluteus maximus—it’s “factory specifications,” if you will—assume that it’s going to do the amounts of cutting, jumping, weightlifting, and sprinting that a habitual endurance runner might need to do. But it requires aftermarket modification to meet the (literally) outsize power and stability requirements of soccer or weightlifting.

Let’s say that a muscle evolved under a particular adaptive pressure. This means that its shape and size literally evolved to do that thing. If you take a muscle that usually doesn’t do a thing for which it evolved to do, and you ask it to do that thing, you are asking it to do something that it has prepared to do for millions of years of evolution.

In order to fit a function that it has been designed to do, the changes in shape and size that the muscle should have to undergo should be smaller, not larger. You would expect a muscle to change far more if you ask it to do something that is less aligned with its evolutionary job description.

Let’s illustrate this by looking at the arm and hand.

We probably all agree that one of the things that specifically sets us apart from our hominid cousins is the ability to coordinate the thumb with the rest of the fingers in order to grasp and manipulate objects to a high degree of dexterity. In its simplest form, this is the capability to oppose the thumb and the fingers—to make an “OK” sign with the thumb and each of the fingers of each hand.

Now let’s take a snapshot of the people who take this unique human ability to its very pinnacle: string musicians, graphic artists, etc. Their livelihood depends on the degree to which they can explore the potential of one of the major evolutionary functions of the human hand.

Compare the forearm muscles of a violinist or painter with that of a weightlifter. The weightlifter’s arms, hands, and shoulders will be much larger and more powerful. (I trust I need not cite a scientific, randomly-controlled study on the matter.) Why? Quite simple: weightlifters engage in activities that develop the body to phenomenal proportions.

But if we go by the conclusions of the article, the fact that the arm and hand get bigger through weightlifting would mean that it didn’t evolve for the kind of fine motor control that you produce in the arts. (Or that lifting heavy objects is its primary evolutionary role). A particularly ambitious version of this argument would be to suggest that one of the core functions of opposition is to become better able to lift heavy objects. But all these suppositions break down when you realize that our primate cousins were not only quite able to grasp branches and use them ably, but that opposition emerges at the same time that hominid arms were becoming smaller (and less powerful), not larger (and more powerful).

Of course, the human hand (and upper extremity in general) still needs to be able to grow and develop in order to be able to lift heavy objects—and can indeed grow to a huge degree to exhibit that function. But its core evolutionary function is to produce the unparalleled dexterity of the human being.

Furthermore, the fact that the non-painter’s hand remains relatively unchanged in size compared to the painter’s hand means that the non-painter’s hand is already relatively set up to perform that kind of dextrous function—because that’s what it presumably evolved to do. This should serve as evidence (not counterevidence) that the hand is primarily for painting (and other fine motor tasks), not for weightlifting.

We should think the same of the gluteus maximus.

Let me conclude by saying that nothing I’ve written here means that the gluteus maximus evolved exclusively for endurance running. Indeed, there is ample evidence suggesting that the architecture of the gluteus maximus is uniquely multifunction as far as muscles go. (In future posts, I’ll delve more into the nuanced view of the gluteus maximus that I proposed above: that it owes its shape and size to the fact that it is a muscle designed for the kinds of “varied explosive and forceful activities” that a bipedal, primarily endurance running animal expects to have to do.)

But what we can say is that the fact that the gluteus maximus gets bigger through a particular stimulus has no bearing on its core evolutionary role, (or on the evolutionary story of the organism as a whole).

Systemic paradigms and their repercussions: the athletic phenomenon of “heel-striking,” and its origins in scientific reductionism.

It would be misleading to say that the philosophical currents that drive society affect our behavior and influence events. It’s much more accurate to say that those philosophical currents largely determine our patterns of behavior and generate those events.

The widespread and damaging athletic phenomenon of heel-striking is no exception.

(By “heel-striking” I refer to the global set of gait characteristics which results in the runner putting their weight on the heel of the landing foot ahead of the center of mass).

Systems thinking proposes that our “mental models”—our belief systems about the world—create the very fabric of society, and therefore the patterns of behavior that emerge. The repercussions that our worldview has on our thought, our social structure, and our lives, are vast, and they are powerful.

Continue reading Systemic paradigms and their repercussions: the athletic phenomenon of “heel-striking,” and its origins in scientific reductionism.

Running form of elite female runners—Analyzed!

I’m posting about a great video I found on YouTube, which analyzes the most important gait components of elite female marathoners. The author of the video analyzes the things that make or break someone’s stride, race, or body.

Here’s the link.

Watch it; it’s well worth your while!

Key points:

  • Runners need muscle resilience in order to maintain tension in the tendons.
  • The lower the amount of force produced by muscle contraction, and the more it is produced by passive tendon release, the more powerful the runner will be.
  • Certain types of gait (gliders vs. gazelles) will aid in efficiency, and boost speed.

The Tales of Forgotten Subsystems, Part II: The “Central Governor.”

Exercise is one of the biggest challenges to the continuous functioning of our body—also known as homeostasis. When we exercise, we wear down tissues, spend calories, consume nutrients, and basically threaten the integrity of our bodies. That’s not a problem: the human body has been designed and built by the creative errors of evolution to be a high-performance athletic machine. And this machine comes with a regulatory mechanism whose purpose it is to ensure that our homeostasis does not become compromised by athletic activity: the “central governor.”

Although this may be obvious to some, it is news to the majority of exercise physiologists, and it is still being debated by cutting-edge researchers. What can you say? Old ideas die hard.

Continue reading The Tales of Forgotten Subsystems, Part II: The “Central Governor.”

Deconstructing “flexibility.”

Throughout our lives, most of us have heard that it is extremely important for us to be “flexible,” for a variety of reasons. Off the top of my head, I’ve been told that flexibility is important to make movement easier, so that my joints don’t deteriorate, and so that I don’t get hurt lifting heavy objects. This is excellent advice. But the problem is that basically all of us go about achieving greater flexibility in exactly the wrong way: by stretching, or more specifically, static stretching. And that is because we don’t understand the concept of flexibility in a mechanically useful way.

One of the main physiological problems of westernized people is poor biomechanics—a phemonemon that basically boils down to the idea that the muscles across our bodies are badly synchronized. Simply stated, they don’t know how to work well together, and when they are subjected to trying circumstances (such as exercise or age), the mechanisms freeze up and become damaged.

For some non-athletes, stretching may help initially. In a very low-risk environment, stretching helps these frozen mechanisms because it increases the net joint range of motion (ROM). This means that the joint can go just a little more before it gets hurt. But that doesn’t solve the problem: the muscles haven’t become synchronized; we’ve only ameliorated the symptoms because we’ve created ROM by isolating the muscles (due to stretchier tendons and weaker muscles), instead of developing their synchronization.

This is a classic case of a systems management problem called “shifting the burden.” We have a perceived need to increase flexibility (because of a particular set of assumptions), and we shift the burden of flexibility away from synchronization and towards isolation. When the symptoms ameliorate, we think that the problem is solved, and we subject it to higher-risk circumstances, such as sports. Soon, we find ourselves caught in an unending roller-coaster of injury.

We can solve this problem. But in order to do so, we must deconstruct our notions of “flexibility.”

Continue reading Deconstructing “flexibility.”