Brains solve movement problems, and it’s true for ours as much as it is for a llama’s. Such riddles require movement as their solutions: writing your name, picking up your soon-to-be-four-year-old, a par four, dodging an opponent, or reaching for your favorite Neil Gaiman novel, signed, from the top shelf.

Some solutions are sustainable because all joints, more or less, do their jobs: forearms pronate and supinate, ankles dorsiflex, plantarflex, evert, and invert, and hips do all the cool things they can.

Unsustainable solutions are when one joint—habitually—does the job of another.

If you avoid twisting your radius and ulna, your brain will find another way to turn your hand over, like internally rotating your shoulder in excess or side-bending your spine.

If you are devoid of dorsiflexion during your morning constitutional, you may lift your heel sooner to stride, bending through your toes instead.

If your hips lack the capacity to handle sideways movement, your brain will find a joint up for the task.

Substitutions can be dextrous adaptations, helping humans (and other animals) solve movement problems in creative ways. Soon after injuries, they are remarkable ways to reallocate forces from torn tissue. But when joints and muscles habitually do jobs they didn’t evolve for, injury risk rises as time passes.

Acquiring Substitutions

How do you wind up substituting one joint for another, anyhow? I see four leading causes: injuries, quantitative deficits, environments, and ill-advisable ideas.

1 - Injuries

Immediately after you’ve injured something, substitutions are fantastic. They allow you to keep living your life while formerly whole tissue puts itself back together.

However, the traditional rehab system focuses on the ankle sprain but fails to see the limp acquired from being in a gigantic plastic boot for weeks.

Or it restores open-chain work of peroneals after an ankle sprain but neglects that those muscles must work in close-chain too, internally rotating and everting the shin during dorsiflexion, like squats, lunges, and direction changes.

Or it treats the knee that used to have an ACL but fails to address the other leg that learned to do the work of two.

So, while acute injuries heal, others slow cook as substitutions proliferate and fester.

The clinician doing this work may realize her omissions, but the insurance companies tie her hands. She’s only allowed to bill the insurance for the torn tissues; a failure of the traditional system.

2 - Quantitative Problems: Energy, Endurance, Strength, Power

GJ lacked a lot of strength and endurance in his left quad. He substituted for its weakness in ways unbeknownst to him, resulting in three years of back pain. His quad was so weak; it was like this twenty-something fourth-round draft pick had never used his left leg to lift weights. We made it stronger through isolation, like a body-builder would, and his three-year-old back pain disappeared—in two weeks. His brain no longer made substitutions for his weak thigh.

How our body can still solve movement problems in lieu of quantitative deficits is so cool, despite their deleterious effects.

In one paper, the authors proved that runners substituted work from their lower leg to their hips once their calves and solei got tuckered out. Runners made substitutions mid-jog to solve their movement problems. (1) That’s astounding—like I’m having a major nerd moment right now—but it’s poor for performance because hips hold big, juicy, and energetically expensive tissue, and the lower legs of runners need the endurance to handle monthly mileage.

If you’re a jogger (soft “j”), the lowest hanging fruit is incredibly simple: increase the endurance of your calf and soleus muscles through several continuous minutes of slow, weighted work—that should be your goal, at least. Start small and sensibly.

3 - Environment

Our environments have become so mundane, so simple that they no longer require all our joints to navigate. Sadly, this results in stories like, “I don’t know what happened! One day I just (woke up / took a step / bent over / went hard in the paint) and bam!”

You might wonder how people don’t use a joint. They don’t move it. Like when Sara locks her knee while walking, or Kristina stops swinging an arm while running, or Z avoids his left leg when coming down from a jump.

If people with habitual substitutions grew up with or submerged themselves in better habitats, like Mother Nature’s rivulets, rocks, and roots, they’d have fewer substitutions and healthier bodies and, arguably, minds. Our bodies never evolved for such convenient and ninety-degreed environments with our eyes occluded from sun and sky.

Alas, some substitutions persist no matter how many hours you spend beneath the branches of redwoods. I wish I could tell you otherwise. One solution, then, is to become aware of them yourself. Watch video of yourself walking, running, and training. Get curious about what your knobbly bits do and where they point. Speed up and slow down the video and see what you notice. Watch it in reverse.

If you’re moving forward, your feet, knees, and arms should generally point forward too.

If you’re doing a pull-up or squat, draw a stick figure of yourself on a screenshot. Just stare at it until something jumps out at you. Some substitutions and asymmetries are easy to see if you just look. Then, reposition yourself based on what you noticed and see what happens.

Or find a coach or practitioner who knows how to identify and remedy substitutions. These people are out there, hard to find, but they’re there. I’m working to make more of them with my Evolved Coach Courses.

Click here for a narrated example of how I watch movement.

4 - Popular But Ultimately Bad Ideas

I intended to write something brief and informative about the ideas that make people move worse but needed many more keystrokes and pixels to get my point across. So, this cause of substitutions gets its own post.

Citations:

Sanno, Maximilian, Steffen Willwacher, Gaspar Epro, and Gert-Peter Brüggemann. "Positive work contribution shifts from distal to proximal joints during a prolonged run." Medicine and science in sports and exercise 50, no. 12 (2018): 2507-2517.

Edelman, Gerald M., and Joseph A. Gally. "Degeneracy and complexity in biological systems." Proceedings of the National Academy of Sciences 98, no. 24 (2001): 13763-13768.

Unseen & Costly Movement Substitutions: Origins, Effects, and Solutions