Supination: Overcoming Gravity On Every Step

Posted on January 16, 2012 by Rick Merriam| 4 Comments
the ghost of you

Photograph by Natalie Harding

“The interplay between force reduction, force production, and proprioception will produce the highest quality of movement. We begin movement by loading the muscles–this is the force–reduction phase.  A stretched muscle can exert more force. Muscles function as shock absorbing structures and springs when they absorb mechanical work while eccentrically lengthening.  – Athletic Development, The Art & Science of Functional Sports Conditioning by Vern Gambetta

(Biomechanics)

This post could have been entitled Plantar Fasciitis/Shinsplints/Runners Knee/Iliotibial Band Syndrome:  Overcoming Gravity On Every Step

We hear a lot about pronation and over-pronation.

I have even heard people say, “You are under-pronating.”

*The* truth is, your ability to supinate is just as important as your ability to pronate.

In fact, it is more important.  (emphasis added)

You have to have success with both, at different times, at different joints, and in different planes throughout the foot in order to have efficiency.

You probably know somebody who has struggled with plantar fasciitis at some point.  The biomechanics are telling us this:  The muscle(s) can not generate enough internal force to accelerate the subtalar joint into a position where it is locked, e.g., Supination.

*The* subtalar joint has to be locked for better propulsion (spring!).

(Boing)

In other words,  plantar fasciitis is not an over-pronation issue.

Plantar Fasciitis is an inability of the muscles to overcome gravity on each and every single leg landing throughout your run.

You have to have supination at the subtalar joint in order to lock up the joint.

Supination at the subtalar joint is a combination of motions when the foot is on the ground:  Inversion of the calcaneus (heel), and abduction and lateral rotation of the talus.

Supination is when the body parts throughout the foot are moving against gravity.

The muscles are shortening *and* generating enough internal force to move a body part against the pull of gravity.

The neuromuscular (fascial) system wants to take advantage of the stored elastic energy.

If the muscles throughout the foot can not contract (stabilize) at the right time, in the right plane and at the right joint, you have an energy leak–a decrease in efficiency.

Inefficient motion anywhere in the chain will–over time–lead to an injury somewhere in the chain, e.g.,  Iliotibial Band Sydrome.

(Prevention)

Pronation is when the body parts throughout the foot are moving with gravity (or collapsing!).   The muscles are lengthening to control motion(s) at a joint.  The muscles are also working together to dissipate the force of gravity, ground reaction forces *and* momentum.

(Optimal Stiffness)

If your thought process (a mindset!) relies heavily on stretching, I do not recommend reading the remainder of this post.

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Stretching: Red Means Stop

Posted on January 8, 2012 by Rick Merriam| Leave a comment

Photograph by Natalie Harding

“If the midfoot and arch creates the first spring, the second spring in your natural shock-absorption system is your Achilles tendon–the strongest, most resilient, and elastic tendon in your body. Your achilles tendon connects your calf to your heel and can handle a ton of weight.  The achilles is essential for efficient running and forward propulsion.  Unfortunately, when you land on your heels, you lock out almost all of its abilities.”  – Excerpt from BAREFOOT RUNNING by Michael Sandler

(Biomechanics)

This is the story, before the story on stretching.

A few days ago, I received a notice in the mail–it was informing me that I didn’t stop at a red light on a street that I have driven on hundreds of times.

The upper right corner of the notice reads like this:  RED MEANS STOP

The frontal lobe of my cerebrum (my modern brain) was trying to figure out the logic in this traffic violation, that unfortunately…I don’t even remember.

It went something like this:  I must have been past the point of no return, and could not stop that quickly–maybe the light changed faster than normal that day…

It must be true; the document provided me with a image of my car *and* license plate.  I can even see two additional images and a video of my traffic violation online.

Now, whenever I’m approaching a light and the the light turns yellow–my prehistoric brain (that is identical to a lizard’s!) is screaming…RED MEANS STOP.

“With barefoot running or minimalist shoes or footwear you get everything about barefoot running except the nutrition–the stuff that actually makes barefoot running beneficial”.  – Barefoot Ken Bob Saxton

(Proprioception)

I’m going to ask you to use your occipital lobe–a underutilized section (lobe) of your cerebrum– for a moment:  Imagine that you and I heat up a small piece of hard taffy candy in the microwave–when we take out the taffy, we notice that the structure of the candy has been altered–it is no longer hard. It is actually very pliable.

If you hold one end, I can stretch it really far with very little effort.

Then both of us can grab a strand of the original strand, and stretch each of the new strands in a different direction.

By heating up the hard candy–we not only changed the structure–we also changed the function.

*That* piece of taffy will never return to its original shape.  (emphasis added)

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Neuromuscular Acceleration: Making The Transition

Posted on December 18, 2011 by Rick Merriam| 1 Comment

“Billions of neurons pass electrical messages down the spinal cord, which feeds the information to the body’s nervous system.  Triggering the muscle cells to contract, the signal in turn becomes a gesture.  The colossal task of coordination falls to the cerebellum.  Containing more than 50 percent of the brain’s neurons, the cerebellum is the seat of synchronized motion.  It provides us with the means to do everything from staying on a bicycle to swinging a golf club.  Without it, muscles can’t function in time with one another.”  – The Motor Cycle Diaries by Victoria Schlesinger, from THE BRAIN — An Owner’s Manual

(Biomechanics)

Photograph by Natalie Harding

A muscle is like a spoke on a bicycle wheel. When it is contracting optimally it is pulling (contracting) to maintain the balance at a joint, e.g., Centration.

When one spoke  on the wheel is loose (weak), you no longer have the ideal balance *and* other muscles have to over-work (tighten up).

It is a guarantee:  Your muscles will always tighten up to compensate for the weak muscle at a joint(s).

*Your* brain is very deliberate. It is doing anything within its power to protect your joint(s) from an injury.

Telling a different story.

(Leverage)

A muscle that is not pulling its weight at one joint will place more stress on a joint above *or* below, e.g., Runners Knee.

The most important muscle for a runner is conveniently located very close to the ground.

(Proprioception)

When the tibialis anterior *or* any other muscle is not receiving all of the neurological input it is considered  to be weak.

The frequency of the neurological input is distorted, and the muscle(s) is not receiving enough input to contract when called upon.

*The* muscle can not generate a sufficient amount of internal force to reach the magnitude that is considered normal.

Tibialis anterior is a great example of how a single muscle with all of its complexity can (and will!) wreak havoc on the entire chain.

Here is that lazy word again…compensation.

*That* explains why your calves are always tight, and you feel the need to stretch them every single day without fail.

The truth is, they will continue to tighten up until you address the opposing muscle(s).

Here is a list of all of the things your tibialis anterior is responsible for:

  • Accelerates the foot into a position(s) of inversion and dorsiflexion to prepare the foot and the chain for a successful single leg landing
  • The combination of dorsiflexion and inversion of the foot drive the lower leg medially.  The tibialis anterior accelerates transverse plane motion (rotation) of the lower leg in the open-chain.
  • Decelerates the foot as it meets the ground.  This is the case for both midfoot/forefoot contact and heel contact (not recommended since it takes so long to get to the big toe.)
  • Controls the medial longitudinal arch to prevent over-pronation
  • Pulls the lower leg over the foot, e.g., Dorsiflexion of the leg at the ankle joint

Your brain will not allow a joint to go into a position(s) where the body does not feel (sense!) stability.

When the tibialis anterior is not receiving optimal input the lower leg can not rotate in which is a component of pronation *or* a collapsing of the chain after the foot initially meets the ground, e.g., Flexion.

The short head (and long head) of the biceps femoris (hamstrings) will tighten up to compensate for the lack of neurological input to the tibialis anterior.

*Your* lateral hamstring will tighten up to prevent the lower leg from rotating in.

A tight lateral hamstring will have an impact on how your foot meets the ground which probably does not sound like much, but it is.

This is one of the biggest reasons why people who transition to a minimal shoe (or barefoot) end up with a stress fracture early on.

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Runner’s Knee

Posted on December 11, 2011 by Rick Merriam| Leave a comment

“Tribology is defined as the study of the mechanisms of friction, lubrication, and wear of interacting surfaces that are in relative motion.  Based on the similarities of biomechanical and mechanical systems, the premise for insuring the efficiency and longevity of the components of the human movement system is maintaining precise movement of rotating segments.”  – Shirley A. Sahrmann, PhD, PT

(Biomechanics)

Your knee joint is a bi-axial synovial joint.

*You* and I have two invisible lines that run through our knees. They are referred to as axes in a biomechanics lab or class.

You can attend a biomechanics class at a university anywhere in the world, and the professor will tell you that you have a horizontal axis that runs from the inside of your knee to the outside of your knee, e.g., A mediolateral (fronto-horizontal) axis.

(Principles)

The other axis at your knee is vertical *and* it allows for rotation of your lower leg at the knee joint.

The same vertical axis allows for rotation of your femur at the knee joint.

At the same time that your femur is rotating at your knee joint; the other end of the bone is also rotating at your hip joint around an invisible vertical axis.

While your femur is rotating at the knee *and* the hip joint; your pelvis is also rotating on your femur at the same joint.

*All* of the motion and much more is driven by your foot as the forefoot/midfoot makes contact with planet Earth.

*Right* below your ankle joint, you have a joint that is formed by the meeting of two bones called the talus and calcaneus (heel).

Your talus sits on top of your heel and these two distinctive bones make-up the very unique *and* extremely important subtalar joint.

(Priorities)

The joints throughout your big toe (1st ray) are the only joints that are functionally more important than your subtalar joint.

If you don’t have a subtalar joint that allows for normal (natural) motion, range of motion at your knee will be limited.

A restriction in range of motion at the knee does not allow you to be an efficient shock absorber on each *and* every single leg landing.

*Running* (not walking) is a series of single leg landings.

(Proprioception)

The mechanoreceptors in and around your knee love to reach the extremes of joint motion in all three planes, e.g., Abduction of your lower leg at the knee joint.

Your knee is reacting to your foot, and your hip is responding to your knee (and foot!) .

At the same time that your pelvis (hip) is reacting to your knee, your spine is responding to motion of your pelvis, your cranium is reacting to the motion of your cervical spine, and your temporomandibular  joint (jaw) is driven by your cranium, which is resting on the top of your spine.

*Everything* is connected in more ways than one.  (emphasis added)

Asking a different question.

It is very unproductive to look at pain and degenerative changes at the knee without first exploring the mechanics of the foot *and* hip, e.g., Runners Knee.

If you limit motion throughout the support (foundation) system; you limit motion throughout the chain.

(Curiosity)

Think of it like a recipe that you are following in the kitchen:

Leave out one ingredient (a component part) and the end result is altered considerably.

(Perspective)

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