Neuromechanics?  This early in the morning?

It has been a while since we have done a neuromechanics post. While doing some research for one of our PODcasts, We ran across this paper: http://www.ajronline.org/content/184/3/953.full

It’s title?

Midbrain Ataxia: An Introduction to the Mesencephalic Locomotor Region and the Pedunculopontine Nucleus

Yikes! What a mouthful!

What’s the bottom line?

The paper review a condition called “gait ataxia”. In plain English this means “aberrant or unsteady” gait. Things which usually cause gait ataxia originate in an area of the brain called the cerebellum, which coordinates all muscle activity. If you drink to much alcohol, it affects your cerebellum and you have a “wobbly” gait : ).

This paper looks at another area of the brain called the midbrain. It is the top part of the brainstem and contains an important gait integration and initiation center called the “midbrain locomotor nucleus”. The paper looks at 3 different cases and has some cool MRI images to see, along with alot of fancy neurological words and pathways.

Whenever we see gait ataxia, we think of impaired proprioception (look here for a bunch of posts on that, or at this post specifically).

There are many factors to consider when evaluating ataxic (or wobbly) gait, and this just gives us all one more place to look.

The Gait Guys. Making you smarter every day!

Understanding Neuroreceptors: Movement Concepts

For all you inquiring minds out there, here is a question on one of our YOUTUBE videos we though was worth making into a post.

Question: “Dr Waerlop says that GTO’s (golgi tendon organs) inhibit muscle tension and muscle spindle apparatuses (MSAs) increase muscle tension. But then he says to treat the attachments (GTOs) to increase the tension and the bellies (MSA’s) to decrease. Seems counterintuitive. What is the modality of tx, acupuncture? Massage?…..What is your modailty for treating these? And does that modality inhibit those neurosensors or stimulate them?”

Answer: GTO’s are high threshold receptors that actually modulate muscle activity through inhibition  (Ib afferents) and Spindles are lower threshold receptors receptors that modulate overall activity, particualrly length. Think of the GTO’s as responding to tension and the spindles as responding to muscle length. Spindles are more in the belly of the muscle and GTO’s at the musculo tendonous junctions. By treating the origin and insertion of the muscles, you can modulate both, whereas treating the belly of the muscles, seems to affect the spindles more.

By treating the origin and insertion of the muscles, you can modulate both, whereas treating the belly of the muscles, seems to affect the spindles more.

The modality can be manual or acupuncture stimulation of the origin/ insertion of the muscle that tests weak.We find that acupuncture seems to work bestbut manual methods work just fine as well. We believe we are normalizing function, rather than specifically inhibiting or exciting. Like Chinese medicine, we are balancing the Yin and the Yang, creating homeostasis.

The Gait Guys: Making it real. Making it understandable. Making it happen : )

Proprioceptive effects of aging: It’s all in the details

Here is a brief video of a gentleman that presented to us with neck discomfort and limited range of motion. Step through it several times before proceeding.

Hopefully, you noted the following:

Increased arm swing on the right (or, decreased on Left)

Pelvic shift to the left on Left stance phase

Decreased step length on the left

Hip hike on Left during Right stance phase

The patient does not have a leg length deficiency.

We remember that there are 3 systems that keep us upright in the gravitational plane:

1. vision

2. vestibular system

3. proprioceptive system

We also remember that as one of these systems become impaired, the others will usually increase their function to help maintain homeostasis. All these systems are known to decline in function with aging. So we have 3 systems breaking down simultaneously.

Did you also note the head forward posture, to move the center of gravity forward? How about the subtle head tilt to the right and “bobble” right and left? Motions which have to do with the head are functions of the vestibular system. He is attempting to increase the input to these areas (by exaggerating movements) to increase input.

How about the glasses? Presbyopia (hardening of the lens) makes it more difficult to focus. Movement (detected largely by rods in the eyes have a much higher density than cones, which are for visual acuity). By moving the head, he provides more input to the visual (and thus nervous system)

Amplified extremity movements provide greater input to the proprioceptive system (muscle spindles and golgi tendon organs (GTO’s), as well as joint mechanoreceptors).

Think of the cortical implications (and effects on the cerebellum, the queen of motor activity and important component for learning).  You are witnessing the cognitive effects of aging playing out on the ability to ambulate and its effect on gait.

 So what do we do?

Improve quality of joint motion, whether that is mobilization or manual methods to improve motion where motion is lost. Perhaps acupuncture to help establish homeostasis and improve muscular function. There are many options.

Postural advice and exercises

Core work

Proprioceptive exercises (like head repositioning accuracy, heel to toe and heel to shin)

Gait retraining

 You get the idea. Providing some of that increased input for him and helping the system to better process the information will be the key to improving his function and helping to counteract and maybe slow the effects of aging on the locomotor system.

We are the Gait Guys. Two geeks, giving you the info so we can all make a difference, every day

Special thanks to RM, who allowed us to use this video for this discussion.


Copyright 2012 , The Gait Guys/Homunculus Group

Materials and content cannot be used, copied or distributed without proper author credit /reference or without prior written consent.

http://wp.me/p1DeXj-JY

Neuromechanics Weekly: How does appropriate movement diminish pain?

We talk about proper (or should we say appropriate) movement (including gait) inhibiting or diminishing pain. So, how does that happen?

Above on the left is a great diagram that we will…

View Post

shared via WordPress.com

The nervous system often takes the path of least resistance. Gait compensations are similar. What you are sometimes are seeing is the “least common denominator” with regards to compensation and conservation of energy.  Here is an article that exemplifies this finding.AbstractWhen sharing load among multiple muscles, humans appear to select an optimal pattern of activation that minimizes costs such as the effort or variability of movement. How the nervous system achieves this behavior, however, is unknown. Here we show that contrary to predictions from optimal control theory, habitual muscle activation patterns are surprisingly robust to changes in limb biomechanics. We first developed a method to simulate joint forces in real time from electromyographic recordings of the wrist muscles. When the model was altered to simulate the effects of paralyzing a muscle, the subjects simply increased the recruitment of all muscles to accomplish the task, rather than recruiting only the useful muscles. When the model was altered to make the force output of one muscle unusually noisy, the subjects again persisted in recruiting all muscles rather than eliminating the noisy one. Such habitual coordination patterns were also unaffected by real modifications of biomechanics produced by selectively damaging a muscle without affecting sensory feedback. Subjects naturally use different patterns of muscle contraction to produce the same forces in different pronation-supination postures, but when the simulation was based on a posture different from the actual posture, the recruitment patterns tended to agree with the actual rather than the simulated posture. The results appear inconsistent with computation of motor programs by an optimal controller in the brain. Rather, the brain may learn and recall command programs that result in muscle coordination patterns generated by lower sensorimotor circuitry that are functionally “good-enough.”J Neurosci. 2012 May 23;32(21):7384-91.

The nervous system often takes the path of least resistance. Gait compensations are similar. What you are sometimes are seeing is the “least common denominator” with regards to compensation and conservation of energy.  Here is an article that exemplifies this finding.

Abstract
When sharing load among multiple muscles, humans appear to select an optimal pattern of activation that minimizes costs such as the effort or variability of movement. How the nervous system achieves this behavior, however, is unknown. Here we show that contrary to predictions from optimal control theory, habitual muscle activation patterns are surprisingly robust to changes in limb biomechanics. We first developed a method to simulate joint forces in real time from electromyographic recordings of the wrist muscles. When the model was altered to simulate the effects of paralyzing a muscle, the subjects simply increased the recruitment of all muscles to accomplish the task, rather than recruiting only the useful muscles. When the model was altered to make the force output of one muscle unusually noisy, the subjects again persisted in recruiting all muscles rather than eliminating the noisy one. Such habitual coordination patterns were also unaffected by real modifications of biomechanics produced by selectively damaging a muscle without affecting sensory feedback. Subjects naturally use different patterns of muscle contraction to produce the same forces in different pronation-supination postures, but when the simulation was based on a posture different from the actual posture, the recruitment patterns tended to agree with the actual rather than the simulated posture. The results appear inconsistent with computation of motor programs by an optimal controller in the brain. Rather, the brain may learn and recall command programs that result in muscle coordination patterns generated by lower sensorimotor circuitry that are functionally “good-enough.”
J Neurosci. 2012 May 23;32(21):7384-91.

Muscle coordination is habitual rather than optimal.

View Post

shared via WordPress.com

“It was suggested that the most important criteria in the selection of running shoes are fit and comfort. Running shoes that meet these criteria are likely to provide optimal levels of cushioning and stability.”www.med.nyu.eduMore evidence that perception is reality; just like one of our other posts about a persons perception of what the shoe will do and what it actually does. Looks like the brain may know best!The Gait Guys

Shoes and Shoe fit

View Post

shared via WordPress.com

Slow Your Gait & Shorten Your Stride and Your Brain May Slow

Slow Your Gait & Shorten Your Stride and Your Brain May Slow

Slow Your Gait & Shorten Your Stride and Your Brain May Slow

Well, you have heard it here before, the receptors drive the brain, and here is another study that backs this up. Remember that receptors, which include not only joint mechanoreceptors, but…

View Post

shared via WordPress.com

Slow Your Gait & Shorten Your Stride and Your Brain May Slow

Slow Your Gait & Shorten Your Stride and Your Brain May Slow

Well, you have heard it here before, the receptors drive the brain, and here is another study that backs this up. Remember that receptors, which include not only joint mechanoreceptors, but also muscle mechanoreceptors (muscle spindles and golgi tendon organs) and tactile receptors in the skin (Merkels discs, paccinian corpuscles, etc) feed into the brain cortex (via the dorsal column system) and the cerebellum (via the spino cerebellar system). This afferent (sensory information) input is important for proper coordination as well as cognition and learning.

Remember, your brain is always remodeling. Here, the old adage “if you don’t use it, you will lose it” applies. More input = more synapses = more neuronal growth. So less motion = less input=synaptic atrophy = fewer connections and thus slower brain function.

Increased speed and length of stride stretches receptors more; decreased speed and shorter stride lengths decrease receptor activation. So, take big steps quickly, or you may turn into a zombie ! There is a reason why they walk slowly !

In July 2012 at the Alzheimer’s Association International Conference in Vancouver, British Columbia Mayo Clinic researchers presented research indicating that walking problems such as a slow gait and short stride are associated with an increased risk of cognitive decline. Computer assessed gait parameters (stride length, cadence and velocity) in study participants at two or more visits roughly 15 months apart. They revealed that participants with lower cadence, velocity and length of stride experienced significantly larger declines in global cognition, memory and executive function.

references:

http://www.aansneurosurgeon.org/2012/08/02/slow-gait-short-stride-linked-to-increased-risk-of-cognitive-decline/

http://www.newswise.com/articles/view/591437/?sc=dwhn

The Essex Swagger: Are Gait (Walking and Running) Styles Cultural and/or Geographical ?

Do Australians move like Americans ?  Does a woman in Israel move like a woman in Ireland ? Do Swedish men move differently than a rural farmer in Tibet ?

Sure there are many variables that come to mind that can drive differing answers; things like foot wear (winter boots, rugged rural shoes/boots to fashionable Manhattan), terrain, tight or loose clothing an so on.  But the main question we are asking here is this: are there cultural and geographical differences in the way we walk devoid of issues related to climate, terrain, and fashion?  In other words, because of our deeply rooted genetic codes that may have been slightly tweaked over the centuries, are there subtle differences in the way these different cultures walk and run ?

Recently we came across an internet article on a gait study “College walking study to capture the Essex swagger” being done at the Chelmsford University . Scientists at Anglia Ruskin University, in Bishops Hall Lane, are calling on people to help them capture “the Essex swagger”, which could help provide better treatment for UK patients.  The gait analysis lab, at the university’s postgraduate medical institute, is a replica of the one at the Hospital for Special Surgery in New York, the leading hospital for orthopaedics in the United State so one might assume this is no meager investigation.

He believes establishing a local database will allow more accurate testing and analysis of patients, ranging from burns victims to those who have just undergone hip or knee surgery.

Dr Rajshree Mootanah, director of the university’s medical engineering research group mentioned that “When we are working with patients it is important to have a reference database of ‘normal’ gait to compare them to. The only database we have is of the New York population and we believe there may be slight, but still significant, differences to the way our local population walks due to the different racial make-up of the two groups.” 

So the bigger question is in fact, are geographic and/or cultural differences present significant enough to warrant different baselines for gait studies ? This question had us looking deeper into the research.  Unfortunately there is not much in the literature on transcultural movement differences but what we did find was supportive of our hypothesis.  To keep this blog article within readable limits for now, we have included the two journal articles we wanted to mention to support the hypothesis.  In Ebersbach’s study (references below) the

“healthy subjects in Berlin showed faster gait velocity than their counterparts in Tyrol, Austria, and patients with Parkinson’s disease were slightly slower than their respective healthy peers in both environments”.

Surprisingly, his study found that patients with Parkinson’s disease from Berlin had significantly faster walking speeds than both patients and healthy control subjects from Tyrol. There was a high gait tempo in Parkinsonian patients from Berlin characterized by fast step-rates and short strides. Thus, it appeared that in Ebersbach’s study there were sociocultural differences in gait, even in disease processes such as Parkinson’s disease. This certainly opens ones eyes into the understanding of disease. After all, we thought that a disease was a disease, not matter what part of the world you are in. And this study shows that this may not be the case.

In Al-Obaidi’s study the gait of healthy young adult Kuwaiti subjects from both genders were compared those in Sweden. The study indicated several significant differences between the subjects in their manner of walking regarding walking at “free, slow and fast” rates.

Both of these studies suggest that people move differently from each other around the world, and surprisingly, even differently from within the disease group of “movement impairment syndromes”. People in Australia move different from those in England, Canada, Germany, Sudan etc.  it suggests that our gait is as unique as our language and as subtle as an accent within a common tongue.  The studies also  suggest that if the gait world is to expand further in terms of research that multi cross-cultural data bases must be built.

Shawn and Ivo, The Gait Guys.

Two geeks looking for the missing links in how humans move.

_______

Mov Disord. 2000 Nov;15(6):1145-7. Sociocultural differences in gait. Ebersbach G, Sojer M, Müller J, Heijmenberg M, Poewe W. Source

Fachkrankenhaus für Bewegungsstörungen/Parkinson, Beelitz-Heilstätten, Germany.

Abstract

Transcultural differences in routine motor behavior and movement disorders have rarely been assessed. In the present study gait was studied in 47 healthy inhabitants of Tyrol living in rural or semi-urban (Innsbruck, Austria) settings and 43 healthy subjects residing in Berlin, Germany. In addition, gait was assessed in 23 patients in early stages of idiopathic Parkinson’s disease (11 in Berlin, 12 in Innsbruck). Healthy subjects in Berlin showed faster gait velocity than their counterparts in Tyrol, and patients with Parkinson’s disease were slightly slower than their respective healthy peers in both environments. Surprisingly, patients with Parkinson’s disease from Berlin had significantly faster walking speeds than both patients and healthy control subjects from Tyrol. High gait tempo in parkinsonian patients from Berlin was characterized by fast step-rates and short strides. Differences in normal gait in different sociocultural settings are thus reflected in parkinsonian slowing of gait.

________

J Rehabil Res Dev. 2003 Jul-Aug;40(4):361-6. Basic gait parameters: a comparison of reference data for normal subjects 20 to 29 years of age from Kuwait and Scandinavia. Al-Obaidi S, Wall JC, Al-Yaqoub A, Al-Ghanim M. Source

Department of Physical Therapy, Faculty of Allied Health Sciences, Kuwait University, Kuwait.

Abstract

This study obtained measurements of the spatiotemporal gait parameters of healthy young adult Kuwaiti subjects from both genders and compared the data to those collected in a similar study performed in Sweden. Thirty healthy subjects volunteered to participate in the study (which included being asked to walk at their “free,” “slow,” and “fast” self-selected speeds). We collected the spatiotemporal gait data using an automated system. Descriptive statistics were calculated for each variable measured at each walking condition. The data were then compared to those from the Swedish study. The results indicate several significant differences between Kuwaiti and Swedish subjects in their manner of walking. These results suggest a need to include data from subjects with diverse cultural backgrounds when a database on normal gait is developed or a need to limit the results of the database to a specified ethnic population.