Midfoot Transformational Zone Discussion

Midfoot TZ Discussion (& other stuff):

Human movement is the synchronized dissociation of body part/segments. If two bones move with the same speed and same direction, the joint feels nothing

The foot consists of 26 bones, 33 joints, 34 muscles - interaction is important.

Foot needs to be mobile when it hits the ground in order to adapt to the surface below.

Foot needs to be rigid during the back phase of gait in order to propel off a stable surface

A transformational zone is a point in time when the body stops moving in one direction and begins moving in the other direction.

When assessing TZ’s, know what motions are supposed to happen in each joint and observe for it. If it doesn’t happen, ask WHY?

1st phase: Foot (heel) hits the ground - Bottom up driver = Bottom bone moves faster than the top bone
2nd phase: Preparing for toe off - Top down driver = Top bone moves faster than the bottom bone

In gait, midfoot mobility is important for synchronized dissociation between the forefoot and rearfoot to occur. This allows the joints to feel/perceive motion.

Bottom up driver: When L foot hits the ground, L calcaneus everts, L talus dives down and in, tibia and femur rotate inwards.
Sagittal: The rear foot starts in DF. As it hits the ground it, goes through a moment of PF. The forefoot relative to the rearfoot is DF. Therefore, the forefoot feels DF
Frontal: When the rearfoot hits the ground, talus dives down and in, calcaneus everts. The rearfoot is ADD, relative to that, the forefoot experiences ABD (this is important for turning on the lateral glutes)

*Disclaimer* the forefoot can’t ABD. It is a relative movement to the rearfoot which is ADD as it hits the ground

Transverse: If the calcaneus everts as it hits the floor, the forefoot also everts. Therefore, the whole foot rolls towards the middle. Usually, the 1st TZ of gait is a bottom up driver, except into the forefoot because the rearfoot is proximal to the forefoot and the rearfoot hits the ground first when walking/running (making this joint a top-down driver). Since the rearfoot everts faster than the forefoot, the forefoot relative to the rearfoot experiences inversion
A combination of the triplane motions above allow the correct dissociation in the midfoot that will allow proper glute activation to occur
Correlation: individuals with weak/inhibited glutes who are unable to control the 1st TZ or have their knees wobbling around during a single leg squat usually lack dissociation between their forefoot and rearfoot.
This can be attributed to the inability of the cuneiform to move in all three planes of motion. Ideally they should be able to wiggle the cuneiforms up and down (sagittal), side to side (frontal) and invert/evert (transverse)
This is important as immobility of the midfoot in the 1st TZ will affect the 1st TZ of the hip (flex, ADD, IR) during gait.

The back phase of gait needs to be a rigid lever. The motions in the back foot are almost a reversal of the motions in the midfoot at the 1st TZ of gait.
As the R leg swings forward in preparation for its 1st TZ of gait, the L foot which was once the front foot, becomes the “back foot”. There is a top down drive in the R foot.
Sagittal: the R rearfoot goes through DF. PF is not considered until the R rearfoot comes off the ground. Therefore, the midfoot feels DF in this plane.
Frontal: in order for the R foot to touch the ground as it swings forward, the pelvis rotates L. This causes the L femur and L tibia to rotate L. As this happens, the R foot swing make the L calcaneus invert. As the rearfoot was in ADD in the 1st TZ of gait, the L calcaneal inversion causes the rearfoot to climb back up on top and go through ABD. Therefore, relative to the rearfoot, the forefoot experiences ADD
Transverse: When the R leg swings through, the L calcaneus inverts because it is responding to L tibia ER. The forefoot also inverts (but the rearfoot does it faster because this is a top down driver). Therefore, the forefoot feels relative eversion
The midfoot needs to lock up in the back phase of gait so that the forefoot has a stable surface to propel off in order to move forward

Should be on the same horizontal axis as toes 2-5.
A lot of times, you’ll see the first ray either above/below toes 2-5. This will change the mechanics of the first ray.
Flexibility: Should be able to passively be pulled upwards and downwards above/below toes 2-5. If it can only clear one direction, it would be considered semi-rigid/semi-flexible first ray. There is an opportunity to create more motion in first ray. If it can’t be moved in either direction, it would be considered a rigid first ray. There is not much that can be done to change this situation.

Individual’s lack the ability to lock up the midfoot at the 2nd phase of gait
This results in the inability to ADD or evert the forefoot and get their big toe on the ground. Therefore, these individuals are propelling off an unstable surface.
Individuals also tend to have weak intrinsic muscles (muscles at the bottom of feet)
Strategies:

Stand up, L foot toe-in, L foot step back toe to heel x3 (this reverses the actions and starts forceful lock up of the foot) - Once the reps are finished, have them walk around
Get into a pivot position: L foot pointed straight ahead, R foot perpendicular to L foot, perform a squat keeping the L heel on the ground. This creates all the motions (below the knee) experienced in the 2nd phase of gait. There is tibia ER, calcaneal inversion, talus dives on top of the calcaneus.

In a single leg squat, if the stance leg knee does not dive towards the middle, is wobbling all over or exhibits the inability to attenuate forces during the descending phase - that individual does not have midfoot dissociation.

In gait, if an individual's foot spins out (calcaneus moves in like a “heel whip”) before they toe off, the probable cause would be the inability to lock up the midfoot.
If an individual has 1) weak glute complex or 2) bunions, check midfoot motions in the 1st TZ. The individual might have an immobile midfoot.

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