Exploring the Links Between Human Movement, Biomechanics & Gait
What’s wrong with this picture? (Besides the fact that you probably shouldn’t run with your dog on asphalt)
There’s been a lot of incongruency in the media as of late. This particular gal, with your head rotation to the right is going against the harmony of neurology and physiology. Let me explain…
This particular gal, with her rotated to the right is going against the way the nervous system is designed to work.
In a post in the last week or so (the massage cream one and incongruent movement) we talked about tonic neck responses. When the head is rotated to one side, that upper and lower extremity should extend while the contralateral side should flex. This poor gal is fighting her own neurology!
Also note that she really doesn’t have that much hip extension on the right and increases her lumbar lordosis to compensate. Gee whizz. You’d a thought they would have done better…
Do YOU do joint manipulations or mobilizations? Could you explain how they are working and accomplishing what you think (or say) they are accomplishing?
All of this information applies to ANY articulation, not just the spine. This is essential information that all folks performing manipulations or mobilizations should know.
What ARE the different types of mechanoreceptors and how do they work? How does that relate to manipulation and its effects? How can mechanoreceptors inhibit pain and influence muscle tone? Dr Ivo answers these questions and more in this video, excerpted from a recent seminar.
-“Connections between brain cells – called synapses – are lost early on in several neurodegenerative conditions, and this exciting study has shown for the first time that switching on a cold-shock protein called RBM3 can prevent these losses. http://www.pnas.org/content/111/20/7379.abstract
Walking. You don’t have to have the pedal to the metal. "Those who walked an average of seven blocks per day or more had a 36%, 54% and 47% lower risk of CHD, stroke and total CVD, respectively, compared to those who walked up to five blocks per week.”
The last few weeks , we have been talking about techniques to improve your (or your clients) stretching experience. 1st, we talked about reciprocal inhibition here. Next we talked about post isometric inhibition here. The we spoke about the symmetrical tonic neck reflex (response) here. If there is a symmetrical tonic neck reflex, then there must be an asymmetrical one as well, eh? That is the topic of todays discussion.
The asymmetrical tonic neck reflex was 1st described by Magnus and de Kleyn in 1912 (1). Like in the pictures above, when the head is rotated to one side, there is ipsilateral extension of the upper and lower extremity on that side, and flexion of the contralateral (the side AWAY from where you are rotating) upper and lower extremity. Take a few minutes to see the subtleness of the reflex in the pictures above. Now think about how this occurs in your clients/patients. The reflex is everywhere!
The reflex persists into adulthood (2) and is modulated by both eye movement and muscular activity (3). When there is neurological compromise, the reflex can be more prevalent, and it seems to arise from the joint mechanoreceptors in the neck and its connection to the reticular formation of the brainstem (4). It may modulate blood flow and cardiovascular activity as well (5).
So, how can we take advantage of this? We could follow in the footsteps of Berta Bobath (6) and incorporate these into our rehabilitation programs, which we have done, quite successfully. But rather than read a whole book, lets talk about how you could incorporate this into your stretching program.
Let’s say you want to stretch the right hamstring:
actively rotating the head to the right (see reference 3) facilitates the right tricep and right quadricep AND facilitates the left bicep and left hamstring
through reciprocal inhibition, this would inhibit the right bicep and hamstring AND left tricep and left quadricep
To get a little more out of the stretch, you could actively contract the right tricep and quadricep (MORE reciprocal inhibition), amplifying the effect
We encourage you to try this, both on yourself and your clients. It really works!
Wow, isn’t neurology cool? And you thought it was only for geeks!
The Gait Guys. Giving you info you can use in a practical manner, each and every post. Be a geek. Spread the word.
Before we talk about this next one, we need to give you a little background (neurologically speaking).
Take a look at the picture above and note the posturing of the baby in the 2 positions. These neurological reflexes (or postures) are called symmetrical tonic neck reflexes or responses (STNR’s for short) and were described in animals and men by Magnus and de Kleyn in 1912 (1). This work was later studied and reported by by Arthur Simons in 1916 (2) and later by Francis Walshe in 1923 (3). These were later made popular by Berta and Karl Bobath in the 70’s (who studied Walshes work), whom they are often attributed to (4).
You next question is “Do these persist into healthy adulthood”? and the answer is a resounding YES (5).
Take a look at the picture above again and note the following:
When the neck is flexed, the fore limbs flex (and the muscles facilitating that, bicep, brachialis, anterior deltoid are contracting) and the hind limbs are extending (relatively), with the glutes maximus, quadriceps, foot dorsiflexors contracting.
Note that when the head is extended, the forelimbs are extended and the hind limbs flexed. Think about the muscles involved. Upper extremity tricep, anconeus, posterior deltoid, lower back extensors, hamstrings and foot plantar flexors facilitated.
The reflex is based on the mechanoreceptors in the neck articulations and muscles and are frequently used by us and many others in the rehabilitation field. Generally speaking, looking up facilitates things which make you extend above T12, and flex below T12. Looking down facilitates flexion above T12 and extension below.
We would encourage you at this point to “assume” these positions and feel the muscles which are active and at rest.
So, how can we take advantage of these while stretching?
Think about your head position:
If you are standing up and hinging at the hips to stretch your hamstrings (notice we did not say “bent at the waist”; there is a BIG difference in shear forces applied to your lumbar spine) you would probably want your neck bent forward, as this would fire your quads which would in turn ALSO inhibit your hamstrings, in addition to the STNR inhibiting the hamstring.
If you were in a hip flexor stretch position, you would want you head up, looking at the ceiling to take advantage of the reflex.
We are confident you can think of many more applications of this reflex and trust that you will, as it can apply to both upper and lower extremity stretches. Just remember that this reflex is symmetrical and will affect BOTH sides. Of course, there are reflexes that only effect things unilaterally, but that is the subject of another post.
The Gait Guys. Helping make you better at what you do for yourself and others and assisting you on using the neurology that God gave you.
Simons A (1923) Kopfhaltung and Muskeltonus. Ges.Z. Neurol.Psychiatr. 80: 499-549.
Walshe FMR (1923) On certain or postural reflexes in hemiplegia, with special reference to the so-called “associated movements.” Brain 46: 1-37.
Janet M. Howle . Symmetrical Tonic Neck Reflex in Neuro-developmental Treatment Approach: Theoretical Foundations and Principles of Clinical Practice. NeuroDevelopmental Treatment, 2002 p 341 ISBN 0972461507, 9780972461504
While I was making linguine and clam sauce for my family, one of my favorite foods that I haven’t had in quite some time( and listening to Dream Theater of course) I was thinking about this post. Then I remembered about voice recognition on my iMac. Talk about multitasking!
What do you agree that stretching is good or not, you or your client still may decide to do so possibly because of the “feel good” component. Make sure to see this post here on “feel good” part from a few weeks ago.
If you do decide to stretch, make sure you take advantage of you or your clients neurology. There are many ways to do this.One way we will discuss today is taking advantage of what we call myotatic reflex.
The myotatic reflex is a simple reflex arc. The reflex begins at the receptor in the muscle (blue neuron above) : the muscle spindles (nuclear bag or nuclear chain fibers). This sensory (afferent) information then travels up the peripheral nerve to the dorsal horn of the spinal cord where it enters and synapses in the ventral horn on an alpha motor neuron. The motor neuron (efferent) leaves the ventral horn and travels back down the peripheral nerve to the contractile portion of the myfibrils (muscle fiber) from which the the sensory (afferent) signal came (red neuron above). This causes the muscle to contract. Think of a simple reflex when somebody taps a reflex hammer on your tendon. This causes the muscle to contract and your limb moves.
Nuclear bag and nuclear chain fibers detect length or stretch in a the muscle whereas Golgi Tendon organs tension. We have discussed this in other posts here. With this in mind, slow stretch of a muscle causes it to contract more, through the muscle spindle mechanism.
Another reflex that we should be familiar with is called reciprocal inhibition. It states simply that when one muscle (the agonist) contracts it’s antagonist is inhibited (green neuron above). You can find more on reciprocal inhibition here.
Take advantage of both of these reflexes? Try this:
do a calf stretch like this: put your foot in dorsiflexion, foot resting on the side of the doorframe.
Keep your leg straight.
Grab the the door frame with your armsand slowly draw your stomach toward the door frame.
Feel the stretch in your calf; this is a slow stretch. Can you feel the increased tension in your calf? You could fatigue this reflex if you stretched long enough. If you did, then the muscle would be difficult to activate. This is one of the reasons stretching seems to inhibit performance.
Now for an added stretch, dorsiflex your toes and try to bring your foot upward. Did you notice how you can get more stretch your calf and increased length? This is reciprocal inhibition at work!
There you have it, one neurological tool of many to give you increased length.The next time you are statically stretching, take advantage of these reflexes to make it more effective.
The Gait Guys. Teaching you more about anatomy, physiology, and neurology with each and every post.
We are sure you have read many articles, some written by us, about the good the bad and the ugly about stretching.Regardless of how you slice the cake, we think we can all agree that stretching “feels” good. The question of course is “Why?”
Like it or not, it all boils down to neurology. Our good old friends, the Ia afferents are at least partially responsible, along with the tactile receptors, like Pacinian corpuscles, Merkel’s discs, Golgi tendon organs, probably all the joint mechanoreceptors and well as a few free nerve endings. We have some reviews we have written of these found here, and here and here.
What do all of these have in common? Besides being peripheral receptors. They all pass through the thalamus at some point (all sensation EXCEPT smell, pass through the thalamus) and the information all ends up somewhere in the cortex (parietal lobe to tell you where you are stretching, frontal lobe to help you to move things, insular lobe to tell you if it feels good, maybe the temporal lobe so you remember it, and hear all those great pops and noises and possibly the occipital lobe, so you can see what you are stretching.
The basic (VERY basic) pathways are:Peripheral receptor-peripheral nerve-spinal cord-brainstem-thalamus-cortex; we will call this the “conscious” pathway: and peripheral receptor-peripheral nerve-spinal cord-brainstem-cerebellum- cortex; we will call this the “unconscious” pathway.
Of course, the two BASIC pathways cross paths and communicate with one another, so not only can you “feel” the stretch with the conscious pathway but also know “how much” you are stretching through the unconscious pathway. The emotional component is related through the insular lobe (with relays from the conscious and unconscious pathways along with collaterals from the temporal lobe to compare it with past stretching experiences) to the cingulate gyrus and limbic cortex,where stretching is “truly appreciated”.
As we can see, there is an interplay between the different pathways and having “all systems go” for us to truly appreciate stretching from all perspectives; dysfunction in one system (due to a problem, compensation, injury, etc) can ruin the “stretching experience”.
Hopefully we have stretched your appreciation (and knowledge base) to understand more about the kinesthetic aspect of stretching. We are not telling you to stretch, or not to stretch, merely offering a reason as to why we seem to like it.
As I sit here on a rare Friday afternoon, not working (OK, I am writing this, so sort of working) and looking out at the lake (picture above), while on a family camping trip, I think about a walk on the rocks this morning with my kids. I was watching my very skilled 7 year old jump from rock to rock while my 3 1/2 year old, that thinks he is seven, tried to follow his older brother.
I had my foot on a rock which lowered the front of my foot in plantar flexion and stood on that leg. I noticed that my balance was not as great as it was when my foot was in dorsiflexion. This made me think about pronation and supination. Yes, it is not uncommon for me to think about such things, especially when I have some spare time. That is one of the things about being a foot and gait nerd; these sorts of things are always on our minds.
So, why was my balance off? Did I need more proprioceptive work? Were my foot intrinsics having issues? No, it was something much more mundane.
Pronation consists of dorsiflexion, eversion and abduction. This places the foot in a “mobile adaptor” posture, reminiscent of our hunter/gatherer ancestors, who needed to adapt to uneven surfaces while walking over terra firma barefoot. Supination, on the other hand (which is the position my foot was in), consists of plantarflexion, inversion and adduction. It places the foot (particularly the midtarsals) in a locked position for propulsion (think of the foot position during toe off).
So why when my foot was plantar flexed and adducted while standing on this rock so much more unstable in this supposedly more stable, supinated position? I would encourage you, at this point, to try this so you can see what I mean. When I placed my foot in dorsiflexion on the rock, I was much more stable. A most interesting conundrum for a biomechanist.
Experimenting for a few minutes, alternating plantar flexion and dorsi flexion, gave me the answer. When we are walking on the flats, our foot is (usually) not pushed to the extremes of dorsiflexion; with the front of the foot up on a rock, it is much more so. This “extra” upward force on the front of the foot, provides much more sensory input (and thus proprioception) from the ball of the feet. Take a look at the sensory homunculus and you can see how much brain real estate is dedicated to your foot, especially the front portion. With this information, we are able to apply more force through the posterior compartment of the leg,which is stronger than my anterior compartment (as it is with most folks).
When the front of your foot is in plantar flexion (ie, your heel is on the rock), we have less sensory input to the balls of the feet, and rely more on the anterior compartment (weaker in many folks, including myself) to counterbalance the weight of our body.
Mystery solved: proprioception trumps biomechanics; more proof that the brain is smarter than we are.
The Gait Guys. Solving the worlds great gait questions, one at a time.