Hip Abduction moment?

This was a great question we received, so we thought we would make a post of it, so everyone could benefit.

“@GregLehman: @KineticRev @TheGaitGuys do you guys have a link to your thoughts on how an ER leg allows the quads to create a hip abductor moment? Thanks”

First of all, What IS a hip abduction moment?

In posts, we often refer to a “moment”, meaning almost literally, a few seconds where a certain motion occurs. When are watching someone from behind and see their heel adduct as they get to terminal stance and pre swing (just before they toe off), you are seeing an “adductory moment” of the heel, sometimes referred to as an “adductory twist”.

Now lets think about the hip. Have you ever seen a framing square used by a carpenter? It is an “L” shaped device to make sure things are square (like hanging a door). The hip is kind of like this. It is shaped like an “L” with the neck and head forming the shorter side of the “L” and the femoral shaft forming the longer side. If you imagine the short side of the square attached to the pelvis and now hinging that away from the body, you have abduction of the hip. Normally, this task is tended to (primarily) by the middle fibers of the gluteus medius and posterior fibers of the gluteus minimus, assisted by the quadratus lumborum on the opposite side.

How can the quad be involved?

We remember that the quadriceps has four parts, the vastus lateralis, vastus intermedius and vastis medialis (collectively called “the vasti’) and the rectus femoris.

The rectus femoris proximal attachments are at the anterior inferior iliac spine (this is called the straight or anterior head) and the superior lip of the acetabulum (called the reflected or posterior head) Please see the top of the 2nd picture above, you can see the 2 heads. The distal attachment, after blending with the vasti, is into the patellar tendon and ultimately the tibial tuberosity.

The rectus is an accessory hip flexor and knee extensor, though it not normally a prime mover for either of these motions. It’s amount of action depends on the position of both the knee and hip.  When the knee is flexed, the rectus has less mechanical advantage, because it is placed in a lengthened position; same goes if the hip is extended.  It will be shortened if the hip is flexed and if the knee is extended at the same time, will have a mechanical disadvantage.

Now think about the direction of travel of each of the heads.

The “straight” head actually runs more obliquely from lateral to medial from its proximal attachment (AIIS) to the distal attachment (blending with vasti and patellar tendon); the refelected head runs a similar course, but not as oblique. If you were to externally rotate the thigh (remember, some folks may have an externally rotated foot due to external tibial torsion), it would actually give these heads more mechanical advantage (when the knee is relatively extended, such as at heel strike/ initial contact and toe off/ preswing) as abductors (remember to think from the ground up, closed chain, so the distal attachments are acting more like the origin); thus, the abductor moment we have talked about.

 

There you have it @Greglehman. Thanks for the great question.

 

The Gait Guys. Uber Gait Aficionado’s Extraordinaire. Come and learn with us. Watch us on Youtube; follow us on Facebook and Twitter, see many of our downloads on our payloadz site by clicking here.

 

All material copyright 2013 the Gait guys/ The Homunculus Group. All rights reserved; don’t make us call Lee.

The Power of Facilitation: How to supercharge your run.

While running intervals this crisp, cool 19 degree morning, something dawned on me. My left knee was hurting from some patellar tracking issues, but only on initial contact and toe off. I generally run with a midfoot strike. I began concentrating on my feet, lifted and spread my toes and voila! my knee pain instantly improved. Very cool, and that is why I am writing this today. 

Without getting bogged down in the mire of quad/hamstring facilitation patterns, lets look at what happened.

I contracted the long extensors of the toes: the extensor digitorum longus and the extensor hallicus longus; the short extensors of my toes: the extensor digitorum brevis, the extensor hallucis brevis: as well as the dorsal interossei.the peroneus longus, brevis and tertius were probably involved as well.

Do you note a central theme here? They are all extensors. So what, you say. Hmmm… 

Lets think about this from a neurological perspective:

In the nervous system, we have 2 principles called convergence and divergence. Convergence is when many neurons synapse on one (or a group of fewer) neuron(s). It takes information and “simplifies” it, making information processing easier or more streamlined. Divergence is the opposite, where one(or a few) neurons synapse on a larger group. It takes information and makes it more complicated, or offers it more options.

In the spinal cord, motor neurons are arranged in sections or “pools” as we like to call them in the gray matter of the cord. These pools receive afferent information  and perform segmental processing (all the info coming in at that spinal cord segment) before the information travels up to higher centers (like the cerebellum and cortex). One of these pools fires the extensor muscles and another fires the flexor muscles.. 

If someone in the movie theater keeps kicking the back of our seat, after a while, you will say (or do) something to try and get them to stop. You have reached the threshold of your patience. Neurons also have a threshold for firing.  If they don’t reach threshold, they don’t fire; to them it is black and white. Stimuli applied to the neuron either takes them closer to or farther from threshold.  When a stimulus takes them closer to firing, we say they are “facilitating” the neuron. If it affects a “pool” of neurons, then that neuronal pool is facilitated. If that pool of neurons happens to fire extensor muscles, then that “extensor pool” is facilitated.

When I consciously fired my extensor muscles, two things happened: 1. Through divergence, I sent information from my brain (fewer neurons in the cortico spinal pathway) to the motor neuron pools of my extensor muscles (larger groups of motor neurons) facilitating them and bringing them closer to threshold for firing and 2. When my extensor muscles fired, they sent that information (via muscle spindles, golgi tendon organs, joint mechnoreceptors, etc) back to my cerebellum, brain stem and cortex (convergence) to monitor and modulate the response.

When I fired my extensor muscles, I facilitated ALL the neuronal pools of ALL the extensors of the foot and lower kinetic chain. This was enough to create balance between my flexors and extensors and normalize my knee mechanics.

If you have followed us for any amount of time, you know that it is often “all about the extensors” and this post exemplifies that fact.

 Next time you are running, have a consciousness of your extensors. Think about lifting and spreading our toes, or consciously not clenching them. Attempt to dorsiflex your ankles and engage your glutes. It just may make your knees feel better!

The Gait Guys. Facilitating your neuronal pools with each and every post.

All material copyright 2013 The Gait Guys/ The Homunculus Group. All rights reserved. If you rip off our stuff, we will send Lee after you!

Podcast 41: The Ankle Dorsiflexion Podcast.

Today we talk about many things affecting, impairing, and relating to ankle dorsiflexion, and so much more ! Join us today on The Gait Guys podcast !

A. Link to our server:

http://thegaitguys.libsyn.com/podcast-41-the-ankle-dorsiflexion-podcast

B. iTunes link:

https://itunes.apple.com/us/podcast/the-gait-guys-podcast/id559864138

C. Gait Guys online /download store (National Shoe Fit Certification and more !) :

http://store.payloadz.com/results/results.aspx?m=80204

D. other web based Gait Guys lectures:

www.onlinece.com   type in Dr. Waerlop or Dr. Allen,  ”Biomechanics”

________________________________________

* Today’s show notes:

Neuroscience:

2. Harvard creates cyborg skin
 
3. Wearable tech
 
4. Walking energy audio clip
5. Int J Sports Phys Ther. 2013 Apr;8(2):121-8.

Ankle dorsiflexion range of motion influences dynamic balance in individuals with chronic ankle instability.

 
6. Lower limb biomechanics in individuals with knee osteoarthritis before and after total knee arthroplasty surgery.
7. From a Facebook follower:

Hello there, I’ve been following your stuff for a while now after searching far and wide for solutions to issues I have with my feet/ankles (and the fact I have an interest in what you guys do, I’m going to University in two weeks to study Sports Therapy).
Why I decided to message you now though is because … 

8. Disclaimer

9. National Shoe Fit program and our Payloadz store

10. Online CE October 30th

11. In the media:

Achilles pain and glute control

12. J Strength Cond Res. 2013 Oct 11. [Epub ahead of print]

The influence of load and speed on individuals’ movement behavior.

Look at these kids running …  all but one shows poor form, but remember, these kids are still undergoing neurodevelopment and are learning to control their body parts. Remember, the maturation/myelination of the nervous system usually lags behind the development of the musculoskeletal system. 

In the photo, lets first focus on the happy lad in the green shirt. He sure looks like he is having fun, which is what running should be about in kids. If you try to make running a chore for kids you just might lose their love of it in the process. But our point here at The Gait Guys is to teach. So here in this photo are some good teaching points. You should see:

1- the stance phase leg (right leg) is spun out into external rotation. Not too much of a big deal because we do not know if he has finished the normal derotation process of the limb, sometimes this can carry into the puberty years even though for most kids the process is largely completed by his predicted age.

2- The pelvis has drifted laterally in the frontal plane past a perpendicular line up from his foot. This could mean alot of things including gluteus medius or abdominal weakness but the point here is that he has broken through the lateral line (frontal plane) of support up through the hip-pelvis-core chain. This is going to set up what the the left knee (swing leg) is doing and will set up #3.

3. Cross over gait is virtually guaranteed because of the lateral pelvis drift as noted in #2. It is virtually guaranteed as well because the swlng leg knee coming inwards is dictating it. IF the knee is coming inwards toward the midline the thing attached to it , the foot, is going to follow. The swing leg is a pendulum, if you shift the pivot point of the pendulum (in this case to his right) the pendulum will swing to the right. This is a self-perpetuating cycle and it will not correct without strengthening, awareness and drilling positive feedback changes.

4. Dr. Allen’s current thought experiment on Ballasts (see podcast 38) is playing out here with the left arm of this fella. If the pelvis drifts far to the right, the arm will move away from the body to move some of the left side body weight outwards to negate the right shift. This is pure balance physics.  Arm swing most of the time cannot be corrected without correcting the thing that causes the aberrant arm swing, and that is often (but not exclusively) aberrant lower limb and pelvis-hip-core or foot mechanics. There are exceptions, but often if you fix the lower limb and pelvis-hip mechanics  you will see an immediate change in the arm swing. If you force changes in arm swing without fixing the problem (and that is not to say there are not local arm swing etiologies) you may be  driving strength into a compensation pattern that you may not want or like.

5. The girl in the pink tights  … . she might have been modelling the boy in the green shirt. Same issues, same concerns.

6. The form we love the most ? The boy in the dark blue shirt and black shorts on the far right. Great form, no major issues here. We bet he didn’t hear the starters gun go off.

On a side note, the fella in the green shirt with that form he would be a champion race walker. He already has the hip action right, the cross over that is loved in that sport and the arm swing.  Maybe some exposure to an alternate sport is a better solution here ? Although we are always an advocate for correcting flawed biomechanics.

It is often painful for us to watch kids run. We know that much of the things we hate are temporary because of the neuro-developmental process. But sometimes, if kids run too much at a young age, and are pressed into long running miles or cross country at too young an age, these aberrant mechanics can become their new norm. This is the danger of plasticity in the nervous system. Repeated stimulation of a pattern engrains that pattern and the extent of a brain’s plasticity is dependent on the stage of neuro-development and the brain region affected.  When an aberrant running form is allowed to perpetuate into the mid-teenage years, when the majority of the synapses are already formed and neurologic “pruning” and myelination are ramping up, then the repeated exposure to the aberrant pattern can get the myelination. This is the most frustrating thing for us. We would rather see some intervention early on with the creation, strengthening and myelinating of correct motor patterns through skill development training rather than mileage training, rather than discarding the more appropriate synapses that could have, might have, should have, been formed. Our bodies and brain will develop depending on the exposures and demands put upon it. And here is the big key, if you do not clean up someone’s gait aberrancy(s) early on, one should not wonder down the road why they developed flat feet, bunions, early degenerative knees and the like. This is a fairly predictable machine, but you have to try to intervene early to prevent the slings and arrows of outrageous misfortune later on.

Both the brain and the body will adapt to their environment, whether that is an optimal one or a compensatory one. It can myelinate either pathway. Which one will you choose for your kids ?

Shawn and Ivo, The Gait Guys

Do you kick or scrape the inside of your ankle with the other foot ?

We are moving into the final throws of cross country season now and we are seeing the pathologies creep in and the miles go up. Some of you who have been with us for 3 years  have seen this picture but we realized we did not have a blog post on the problem represented by this photo.  This young runner had these scuff marks on the inside of the right lower leg and ankle after a cross country meet.  So what is going on here and what does it tell you ?

Some runners notice that they repeatedly will scuff in the inside ankle or inner calf with the opposite shoe when running. This can happen on both sides but it is more often present unilaterally than bilaterally. 

This problem, typically, but not always represents one of two things:

1- cross over gait (if you are new to our blog in the SEARCH box type in “cross over” and “cross over gait” and be sure to see our 3 part video on the cross over on our youtube channel found here).

2- negative foot progression angle which may or may not be combined with a degree of internal tibial torsion.  Said easier, the runner is “in-toed” or “pigeon toed” but if you have been here with us awhile on The Gait Guys we expect a diagnosis of a higher order so use the former terms, please.

Lets discuss both.

1- Cross over.  When the runner is standing on the right leg, right stance phase of gait, the frontal plane is not properly engaged and the pelvis can drift further over the right foot. This drift to the right will drop the pelvis on the left side. This will alter the pendulum movement of the left leg. Since the global pelvis is moving to the right the left swing leg pendulum moves to the right as well and as it swings past the stance leg it strikes a glancing blow to the inside of the right ankle or calf. This is simple biomechanics and physics. To fix this problem, which is clearly inefficient, one has to determine what is causing the right pelvis drift (there are many causes, the most often thought of cause is a weak gluteus medius on the right but if you have been here with us awhile you will know there are other causes) and then fix the drift. Do not assume it is the gluteus medius all the time, for if it is not, and you employ more glute medius exercises you could be ignoring the source and building a deeper compensation pattern.  Fix the problem, not what you see.

2- Negative foot progression angle and/or internal tibial torsion.  In order to fix this you have to know first if you are dealing with a fixed/rigid anatomic tibial or femoral torsion issue which cannot be fixed or if you are dealing with a flexible progression angle issue. Often, “in-toeing” is accompanied with internal tibial torsion, this is because the knee has to progress forward to keep its tracking mechanics clean, if you correct someone’s foot progression back to neutral and they have internal tibial torsion then you have dragged the patellar tracking outside the normal sagittal progression angle, knee pain will ensue. In fact, the foot progression on the ankle is normal, but the tibia or femur are merely torsioned in a manner that drags the foot inwards with the long bone orientation, again, this is driven by a higher order/demand, to normally track the patella sagittally (forward).  However, if this is a pre-puberty individual you have time because the long bone derotation process is still occuring. Give homework to encourage a good foot tripod and work to strengthen the external hip rotators and encourage sagittal knee tracking mechanics. This is a delicate balancing act, but it can be done, but it is a monster of a project for a blog post because each case is different, variable and always changing depending on the client progress. Remember, you can only encourage more appropriate mechanics and hope that the body will embrace some of the change and encourage some of the de-rotation process to occur from the long bone growth plates. 

The “inside scuff”, to identify its solution you have to know the cause. After all, if it was as easy a fix as “stop doing that” no one would be doing it and we would be out of a job.

Shawn and Ivo …… The Gait Guys 

Podcast 40: Trips, Falls and NFL Shoe Injuries

Today we talk about trip and fall incidence, the NFL shoe injury epidemic and so much more ! Join us today on The Gait Guys podcast !

A. Link to our server:

http://thegaitguys.libsyn.com/podcast-40-trips-falls-and-nfl-shoe-injuries

B. iTunes link:

https://itunes.apple.com/us/podcast/the-gait-guys-podcast/id559864138

C. Gait Guys online /download store (National Shoe Fit Certification and more !) :

http://store.payloadz.com/results/results.aspx?m=80204

D. other web based Gait Guys lectures:

www.onlinece.com   type in Dr. Waerlop or Dr. Allen,  ”Biomechanics”

* Today’s show notes:

Neuroscience:

 
1. Foramen magnum position in erect ambulation
 
1b: Scientists Identify Protein Linking Exercise to Brain Health

REDDIT TOP NEWS | OCTOBER 12, 2013
http://pulse.me/s/s2PNS 

2.  More on Cannabinoids
 
5.  NFL shoes and injuries
6. From a Blog reader:
Hi guys,

I have been having major leg issues sine my ACL reconstruction  … .
Our DISCLAIMER !, hear it on the podcast. We are NOT your doctor !
7.  From a Blog reader:
Hello, I’m a 19 year old runner trying to get rid of my crossover gait … 
 
8. Another one from a blog reader
Hi, I have a question about externally rotated hip. When i bring my knee up to my chest, my leg turns outward … 
 
9.  Blog
Im really confused with GaitGguys, I follow but this time mixed messages. Recent video showed was varus/lateral boarder push off gait, girl in tennis shoes … 
 
Hi, my name is Paige. I have been working in a sports medicine outpatient clinic for about 2 months now. I love your podcast and recommend it to as many clinicians as possible. I watched your youtube videos on the shuffle gait and have been implementing them into a patient’s home program. They are working great and the patient loves them as well! Just wanted to let you know! I love the videos and hope to take your shoe fit program at some point! You are geniuses and excellent instructors. I’ve learned so much already that we just don’t get enough of in school!
Thanks so much!
Paige