Hitting the Wall: Do Mechanics Matter?

Is there an “correct” solution to a movement problem? Opinions from movements professionals seem to live on a spectrum between two polarized opinions. On one end is the biomechanical purist who would deviate towards the belief that movements need to be precise and align with biomechanical models of efficiency. The extreme end of this argument would posit that there are only a few ways to correctly complete a task and deviation from this will come at a cost. At the other end of this argument are the movement optimists. This side would argue that the human will be able to self organize into “correct” solutions or that repeated exposure to any stimulus will allow for adaptation and tolerance to that position. 

Human as precise machine vs human as adaptable movement amoebas. 

What if both are right? 

The test of a first-rate intelligence is the ability to hold two opposed ideas in mind at the same time and still retain the ability to function.

F Scott Fitzgerald

Context is King

This argument is really pointless without defining the conditions.  “Correct” lives on a continuum. This means there are times when I should and shouldn’t care about the minutia. Biomechanics may not matter AND may be the limiting factor to enhancing performance and managing risk. 

When Should I Care: The Movement Wedge

There are many correct solutions, until there is just one.  Look at the figure below. The thick end of the wedge is the task at its most simple. Low intensity, low volume. The area inside is the options for a “correct” solution. The narrow end is the task at its most demanding. High intensity, high volume. There are very few correct options. 

Left= low constraints, many solutions. Right= high constraints, few options.

A simple example here is picking up an object from the floor and getting it overhead. The task of picking up a feather off the floor and putting it on a shelf lives on the far left side of the wedge. With the lack of demand, there are a multitude of options available for the individual to choose from. Variation here is welcome and desirable. Now change the feather to Lasha Talakhadze performing his world record 220kg snatch. This lives at the extreme right tip of the wedge. Not only must his body perfectly coordinate himself around the rapidly rising mass, he must be specifically built for this task. The solution to this movement problem is the product of nature (specialized anthropometrics) and nurture (years of very specific training) to match the demands defined by physics. 

Now picture the transition from walking to jogging to sprinting. With walking, the forces on the body are relatively low. We are at the thick end of the wedge. The human can get away with more deviation in walking gait over time with less risk of negative repercussions. But now try to run a sub 9.58s 100m. With this amount of intensity, a half of degree of knee extension could be the difference between a world record and a hamstring strain. We must also consider volume. A 5 mile training week may live at the left end of the wedge for many while an 80 mile week lives on the far right. Again, we have come the very edge of the wedge.

The Mechanical Wall

Most of human movements does not live in these polarized ends. We often find ourselves in working in the gray zone in the middle of the wedge. Let’s create a theoretical scenario of two twin runners (Andy and Randy) going through the same training program. Every step and running velocity has been perfectly matched throughout their entire life.  Andy always gets through training perfectly healthy, but year after year, Randy breaks down 2 months into the training cycle with a right tibial stress reaction. You note that Randy seems to have a stiff landing on his right leg and a more supinated right foot compared to his left. When does this matter? 

At a certain point when intensity and volume rise we may meet the mechanical wall. This is the theoretical point where his mechanics matter. Randy could theoretically run 39.9 miles/week at an 7:00 pace for the rest of his life but the transition to 40 miles or a 6:59 pace may tip him over the edge. He has reached the end of his adaptability within the limitations of his mechanics. Prior to this, his deviation was a “correct” solution to his movement demands, but as the demand rises, it is no longer sustainable. The cost of doing business has now exceeded his physiological capacity. The deviation away from our “biomechanical optimum” has potentially limited his ability to adapt beyond this level.

This is the point in my opinion, which biomechanics truly matter. When the stakes rise there is less room for error. And our trends over time with this athlete allow us to understand his physiological limitations. We can couple this n=1 data with our large scale understanding that a stiffer ground contact may predispose a runner to increased tibial stress. We can now run the experiment of decreasing total workload to stay behind this mechanical wall while we invest time in altering mechanics. Once the changes have been made, volume and intensity can again progress to assess how Randy does when approaching this wall. 

“ We can reduce the effect of our biases by combining a large scale understanding of averages with the long term lens of a single athlete”

Sophia Nymphius

Of course, our real world scenarios are never this clean. We will rarely be able to define a precise workload in which the individual consistently breaks down. However, our trends over time coupled with an evaluation of how far away from a biomechanically defined “optimum” their mechanics are may give us some insight into when the juice of changing mechanics is truly worth the squeeze. Practically, the management of a first time injury to a runner with an asymmetrical gait pattern who ramped their volume up 50% over the last month and a chronically injured runner with the same gait deviation following a logical training progression should be viewed  and managed differently.  When making the decision of how to proceed , ask yourself: 

  • What are the injury trends of this individual over time? 
  • How logical has their training progression been? 
  • How far do their mechanics shift away from a biomechanical “optimum”?
  • How much effort will this take for the individual to change their mechanics? 

Arguments over the importance of biomechanics and self organization versus coaching rage on in our profession. But the argument is really pointless without defining the conditions.  Correct lives on a continuum. This means there are times when I should and shouldn’t care about the minutia. Biomechanics don’t matter AND are the most vital element to performance and managing risk. Context is key. Knowing when is the art. 


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