The One-Dimensional Runner
If you’ve ever watched a Marathon on TV, the bird’s-eye view of participants makes it look like a clean, linear flow of humanity moving in a singular straight line towards the finish point. Because of this, it’s easy to assume running is a one-dimensional activity, and most runners train with that exact intention in mind. They focus almost exclusively on the Sagittal Plane—the muscles that flex and extend, like the hip flexors, glutes, and back.
But here’s the catch: what we see at the macroscopic level isn’t what’s happening at the microscopic. Running is not a straight-line activity. It is a sophisticated game of ‘catch’ between your right and left sides.
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Take a look at the anatomy of the pelvis and ribcage, even just a quick Google search. We don’t actually have a pelvis or a thorax; we have a hemi-pelvis and a hemi-thorax. We’re built in two distinct halves. Right and Left. To move forward efficiently, you must first be able to move side-to-side. If you cannot shift your centre of mass from your right foot to your left foot, you aren’t ‘alternating’; you’re simply falling forward and using your lower back to catch you.
The Sagittal Trap
When we lose the ability to effectively shift into our left hip (a trait we explored in The Asymmetry Paradox), we get stuck in a Sagittal Dominance. Because we can’t shift laterally from side-to-side, the brain looks for a shortcut to keep us moving. It recruits a “family” of muscles—the hip flexors, IT Band, and back extensors to name a few—to work together and pull us forward.
This is why when you read Runner’s World, the “Top 5 Warning Signs” of dysfunctional running always seem to include lower back fatigue and IT Band irritation. It’s not that these muscles are “weak”; it’s that they are doing a job they weren’t hired for because you’ve lost access to your Frontal Plane—that essential side-to-side shifting ability.
Finding the “Brake” and “Accelerator”
To escape the Sagittal Trap, we have to give the brain a map for the other two planes of motion. We touched on this in The Ascending Influence—how your choice of footwear influences the way your brain “senses” the floor. We can distill this down to two specific sensory references as it relates to the feet:
The Right Arch: To move to the left, you must first be able to find and feel your right arch. This serves as the “push-off” point that drives your centre of mass over to the left side.
The Left Heel: Once you’ve shifted left, you need the ability to find your left heel. This is your “brake.” It tells the brain: “We’ve made it over to the left side successfully; you can stop tensing the back now.”
If you lack the ability to sense these shifts side-to-side (arch-to-arch) and front-to-back (heel-to-toe), the likelihood is you’ll stay “stuck” on that preferred right-side anchor, even as your body tries to propel itself forward. By finding these references, running stops being a linear, “flex-and-extend” activity and becomes a 4D shift—a series of minute, lateral changes in direction, in sequential time, that allow for true propulsion forward.
A “Running Reset”
If you’re dealing with chronic “clicking” hips, tight hamstrings, or uneven shoulder height, stop trying to stretch the life out of your muscles in the attempt to apply length to these tissues. Instead, consider a shift in your framing of the issue:
Shift Regularly: Whether you’re standing at a desk or waiting to pick the kids up from school, practice shifting your weight over your left leg. Keep the weight through your left heel. You are giving your brain a reinforced “Left Stance” map in a low-stress environment.
Stride with Intent: During your warm-up miles, focus on the relationship between your right arm and left leg. As your left heel strikes, can you reach forward with your right arm? This encourages the thorax to rotate and manage the internal pressure shift toward the left side.
Stop Equating “Tightness” with Stretching: Our default response to tightness is to stretch. In reality, that sensation is often a sign of muscles working overtime to prevent your centre of mass from tipping forward. If you lack the ability to touch your toes, it’s much more likely to be a mapping problem than a muscle length problem.
Testing Your Own “Map”
If you’re a runner who has been stuck in “Sagittal Dominance,” your brain is likely restricting movement to prevent you from tipping outside your base of support. We can measure this “protective tension” using two very simple tests—both of which form a part of our initial client assessments at IFT.
These aren’t just designed as simple flexibility measures with a generic outcome in mind; they act as neurological status updates. They change day-to-day through how much tension you’re holding in the system, and they can be directly altered within a single session because they’re adaptive not static.
The Toe Touch:
Stand with your feel together, knees extended, and on exhalation reach for your toes.
The Goal: You should be able to comfortably touch your toes without straining.
Red Flag: If you’re nowhere near your toes, are unable to breath once in position, or it feels like your hamstrings are made of steel cables, your brain is likely using a global extension pattern to stay upright.
Reality Check: Interestingly, being too flexible (placing your palms flat on the floor with ease) can also be an indicator of a “lost map.” Suggesting that we are now encountering orientation strategies—shifting the pelvis or turning away from midline—to achieve an outcome without a solid “anchor.” In this movement we’re ideally looking for the “Goldilocks” zone: a soft, easy toe touch.
The Straight Leg Raise:
Lie on your back, feet facing the ceiling, and have someone lift one leg (keeping the knee straight) while the other remains flat on the floor.
The Goal: 80–90 degrees of easy movement.
The Red Flag: You feel your body turn away from the testing leg, your pelvis “tips” backward as the leg lifts, or one leg has a wildly different range than the other (e.g., 60° vs 90°).
Reality Check: We need to move past consider this as a “tight hamstring” issue; it’s far more likely to be a pelvic position problem. If one side of the pelvis is metaphorically “stuck” with the Right Brake on, the muscles on that side will feel tense because they are starting from a completely different position than the other side. You have an asymmetrical starting position that is sabotaging your running mechanics before you even take a step.
Why These Matter for Your Next Run
If you “fail” these tests, your body is telling you that it doesn’t feel safe moving in the Frontal (side-to-side) and Transverse (rotational) planes. When you head out for a run with a failed Toe Touch, every stride has to factor in your own protective tension. You are fighting against your internal asymmetry with a strategy that just wants to “pull” you forward, rather than one that shifts and rotates you smoothly from side to side.
Much of the initial homework activities we set for clients is designed to reinforce the “maps” needed to effectively “pass” these tests before you ever lace up your running shoes. We want a clear sense—from the ground up—of what it feels like to find your “Brakes” (heels) and “Accelerators” (arches). We want you to feel the transition between:
Right Stance — Left Swing
Left Stance — Right Swing
By learning to feel the shift between the two sides of not only the pelvis but also the ribcage, you ensure that when you hit the pavement, your body is ready for the three-dimensional reality of the road beneath you. You stop fighting the ground and start using it.
Summary Checklist:
Check your Heels: Can you sense them? (Grounding)
Check your Breath: Can you maintain nasal breathing? (Airway)
Check your Map: Can you touch your toes? (Safety)
If you can give a firm “Yes” to all three, there’s a strong likelihood that you’re no longer just running; you’re now alternating.
AK.