Why does it feel so good to stretch? 

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.

The Gait Guys

Podcast #25: Bionics, Arm Swing & Footwear

Great podcast today, #25. Wide range of topics today: the first truly bionic body part, technical shoe issues, GTO’s and more. 

podcast link: 

http://thegaitguys.libsyn.com/podcast-25-bionics-arm-swing-footwear

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

Gait Guys online /download store:

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

Today’s show notes:

1. The First Truly Bionic Hand

http://www.independent.co.uk/life-style/gadgets-and-tech/news/a-sensational-breakthrough-the-first-bionic-hand-that-can-feel-8498622.html

“The first bionic hand that allows an amputee to feel what they are touching will be transplanted later this year in a pioneering operation that could introduce a new generation of artificial limbs with sensory perception.

2. Effects of toning shoes on lower extremity gait biomechanics

http://www.clinbiomech.com/article/S0268-0033%2813%2900010-7/abstract

Clinical Biomechanics, Jan 2013

3. Beware of trendy barefoot running shoes - you could end up with broken bones in your foot

Read more: http://www.dailymail.co.uk/health/article-2289725/Beware-trendy-barefoot-running-shoes–end-broken-bones-foot.html#ixzz2N5HOO0qk

http://www.dailymail.co.uk/health/article-2289725/Beware-trendy-barefoot-running-shoes–end-broken-bones-foot.html?ito=feeds-newsxml

• Advocates of barefoot running claim it can reduce injuries and back pain
• ‘Minimalist’ shoes such as these now account for 15% of sales
• But experts say many people suffer injuries by overdoing it early on
  
• Runners should make transition from regular trainers more slowly, they say

4. Foot strike and injury rates in endurance runners: a retrospective study.

Daoud AI, Geissler GJ, Wang F, Saretsky J, Daoud YA, Lieberman DE.
Med Sci Sports Exerc. 2012 Jul;44(7):1325-34. doi: 10.1249/MSS.0b013e3182465115.

Department of Human Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.

5. Effects of foot strike on low back posture, shock attenuation, and comfort in running.

http://www.ncbi.nlm.nih.gov/m/pubmed/23073217/
Med Sci Sports Exerc. 2013 Mar;45(3):490-6

CONCLUSION: Change in foot strike from RFS to FFS decreased overall ROM in the lumbar spine but did not make a difference in flexion or extension in which the lumbar spine is positioned. Shock attenuation was greater in RFS. RFS was perceived a more comfortable running pattern.

*it seems to becoming a question as to what you are doing with the body parts at impact……..where it be you are RFS or FFS.  Do you have the ability to protect the parts in varying mechanical stressful positions.

6. Hey guys, Dr. Ryan:

I just listened to Pod 23 and Ivo you mentioned sagittal curves not developing until after birth..  There is evidence they begin to develop in-utero.  Here is an article excerpt and link to it.

 

"In many anatomy texts, it is often claimed and/or assumed that the cervical lordosis is a secondary curve and is not present during intra-uterine life. However, as early as 1977, Bagnall et al³ demonstrated that the cervical lordotic curve is formed in intrauterine life (9.5 weeks). In 195 fetuses, Bagnall et al³ found that by 9.5 weeks, 83% of fetuses have a cervical lordosis, 11% have a military configuration, and only 6% of fetuses are in the typically described kyphotic position of the cervical spine. This means that by 9.5 weeks, 94% of the fetuses are starting to use their posterior cervical muscles to pull the cervical curve away from the fetal “C”-shape. Fetuses have a cervical lordosis before birth, however, the lordosis increases during post-natal life at ages 3 months-9 months as the infant raises his/her head and begins to sit up.^4”

http://www.chiropractic-biophysics.com/clinical_chiropractic/2011/2/11/pediatric-cervical-lordosis-values-disorders-and-interventio.html

REFERENCES

1. Harrison DD, et al. Spine 1996; 21: 667-675.
2. Harrison DD, et al. Spine 2004; 29:2485-2492.
3. Bagnall KM, et al. J Anat 1977;124:791-802.
4. Kure S. J Tokyo Med Collage 1972;30;453-470.
5. Kasai T, et al. Growth. Spine 1996;21:2067-2073.
6. Harrison DE, Harrson DD, Haas JW. Evanston, WY: Harrison CBP Seminars, Inc., 2002, ISBN 0-9721314-0-X.
7. Shatz A, et al. Acta Anat 1994;149:141-145.
8. McAviney J, et al. J Manipulative Physiol Ther 2005;28:187-193.
9. Bastecki A, et al. ADHD: A CBP Case Study. J Manipulative Physiol Ther 2004; 27(8):e14.

7. “Dynamic Arm Swing in Human Walking, (http://www.ncbi.nlm.nih.gov/pubmed/19640879) where it was determined that normal arm swinging required minimal shoulder torque, while volitionally holding the arms still required 12% more metabolic energy. Among measures of gait mechanics, vertical ground reaction moment was most affected by arm swinging and increased by 63% without it.
* brings up issues of shoulder pathology……rot cuff, frozen shoulder, carrying a purse, water bottle etc


8. Winter foot wear:
We like Steger Mukluks…….youtube video   "gait guys mukluks”

9. Versions: one of the more difficult concepts to grasp…………..here is a Q from a FB reader

• Does retroversion mean this child will automatically grow up with abnormal mechanics - leading to possible knee foot hip back issue etc? Is there a fix to prevent such without an ortho’s bone saw?

   

  10. The role of GTO’s in plyometric exercises.

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 : )

A Scientific Look at High Heels

http://well.blogs.nytimes.com/2012/01/25/scientists-look-at-the-dangers-of-high-heels/

PROCEED WITH CAUTION! INFO DENSE POST AHEAD!

Can you think of a better way to start the week than with a discussion of high heels? We all like high heels… Well, at least guys do (and we know quite a few women who do as well…some of you may be reading this post). NO, WE DO NOT LIKE TO WEAR THEM, but we can admire the way they make the calves look so great and the increased lumbar lordosis and accentuation of the greatest gait muscles ever created!

Were they based off “chopines” from the 15th century; an elevated shoe (7-30 inches high!) which kept the peoples feet literally “out of the muck” (they didn’t have modern plumbing back then) or are they older? Or was the heel invented out of necessity to keep horse riders literally “in the saddle” ? Chinese and Turkish history says maybe they were to keep women (particularly concubines) from escaping. For the intents of discussion, we will stick with this last premise, as it fits nicely with the findings of this article (based on the study published here)

Remember the neuromechanics posts on muscle spindles or golgi tendon organs (GTO’s) ? If not, click the links and check them out; suffice it to say that the take home message is: Spindles respond to length and GTO’s respond to tension.

We also remember that GTO;’s modulate the muscles function that they come from. In other words, they literally “turn off” the muscle they come from (it is a disynaptic, post synaptic pathway for you neuro geeks out there). In light of that, lets look at some quotes form the article:

“the scientists found that heel wearers moved with shorter, more forceful strides than the control group, their feet perpetually in a flexed, toes-pointed position. This movement pattern continued even when the women kicked off their heels and walked barefoot. ”

No surprises here. Go up on your toes and take a few strides (more difficult for guys, since the biggest heel we may have is about 12mm in our running shoes). Which muscles are engaging? See how difficult it is to take a full stride? Try to engage your glutes. Not so easy, eh? Now put your foot flat on the floor, extend your toes and NOW engage your glutes. Easier? Presyanptic loading of the motor neuron pool pays big dividends!

They go on to say: “As a result, the fibers in their calf muscles had shortened and they put much greater mechanical strain on their calf muscles than the control group did.”

Hmmm… shortened muscles put under greater tension. Sounds like a job for the golgi’s, and what do they do? Inhibit the muscle from contracting. No wonder is was harder.

“In the control group, the women who rarely wore heels, walking primarily involved stretching and stressing their tendons, especially the Achilles tendon. But in the heel wearers, the walking mostly engaged their muscles.”

Wow, here is evidence They changed their motor programming!  Did you ever think that high heels could change the way our brain works? Maybe it’s a secret plot to take over the world….or maybe not…

The Gait Guys…Lovers of high heels as long as you don’t walk in them….

More on Gait and Vision:  Along the lines of Binocular Parallax….

Yesterdays post talked about vision and parallax. Today’s explores some adaptations we have to poor visual quality. (Note 3 pictures today, toggle amongst them.)

In the attached study, we see people with poorer vision quality had 3 particular gait parameters (although probably had many more parameters) which changed with vision quality:

1. shorter step length

2. less trunk flexion

3. earlier heel contact with the ground (which goes along with shorter step length.)

If we think about what we know about the nervous system, this all makes sense. There are 3 systems that keep us upright in the gravitational plane: vision, the vestibular system and the proprioceptive system. If we remove one of the systems, the other 2 become enhanced (or better said, they had better become enhanced).

In this study they took away (or impaired) vision. This left the vestibular and proprioceptive systems to take over. The vestibular system affects position of the HEAD ONLY and measures linear and angular acceleration.  It makes sense to say that a more upright posture would do wonders for the stability of the system. The semicircular canals found in the inner ear measure angular motion, or rotation. Placing the body upright shifts the position of the semicircular canals in a different posture (particularly the LATERAL semicircular canal, which sits at 30 degrees to the horizontal; ) and places the utricle and saccule (which measure tilt and linear acceleration) in a better position to appreciate these. Translation, correct upright posture and neutral head positioning are critical for their contribution to detecting and maintaining balance and spacial stability.

The study also suggests that earlier heel contact in gait creates an “exploration” of the ground. This is quite important because the foot has so much cortical representation (see bottom picture) and is important for proprioception owing to its 31 articulations LOADED with joint mechanoreceptors, not to mention 4 LAYERS of muscles, LOADED with spindles and Golgi Tendon Organs.  The foot is a highly dense sensory receptor, the problem is we have had it hibernating in shoes for far too long. Imagine the advantage to balance, gait and posture we might have if we hadn’t dampened the mechano-sensory receptors for the better part of our lives. 

So, bringing this all full circle with the study; If you have poor vision, you had better make up for it with good upright posture and a sensory system that is unimpaired.  Most of us could have better posture and could use some retraining of foot function and sensory reception. Blind people generally have good postural and environmental awareness. They are not slouched over leading their gait head first while wearing oven mits on their hands and rigid steel-toed work boots. They take advantage of these systems and optimize them.

Sometimes the simple answers are not as simple as we like, but it is nice to know there is a reason.

The Gait Guys….Providing both simple answers to complex problems and complex answers to apparently simple ones.

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Study: Low vision affects dynamic stability of gait

Gait Posture. 2010 Oct;32(4):547-51. Low vision affects dynamic stability of gait. Hallemans A, Ortibus E, Meire F, Aerts P. Source

Research group of Functional Morphology, Department of Biology, University of Antwerp, Belgium. ann.hallemans@ua.ac.be

Abstract

The objective of this study was to demonstrate specific differences in gait patterns between those with and without a visual impairment… .  Adults with a visual impairment walked with a shorter stride length (1.14 ± 0.21m), less trunk flexion (4.55 ± 5.14°) and an earlier plantar foot contact at heel strike (1.83 ± 3.49°) than sighted individuals (1.39 ± 0.08 m; 11.07 ± 4.01°; 5.10 ± 3.53°). When sighted individuals were blindfolded (no vision condition) they showed similar gait adaptations as well as a slower walking speed (0.84 ± 0.28 ms(-1)), a lower cadence (96.88 ± 13.71 steps min(-1)) and limited movements of the hip (38.24 ± 6.27°) and the ankle in the saggital plane (-5.60 ± 5.07°) compared to a full vision condition (1.27 ± 0.13 ms(-1); 110.55 ± 7.09 steps min(-1); 45.32 ± 4.57°; -16.51 ± .59°). Results showed that even in an uncluttered environment vision is important for locomotion control. The differences between those with and without a visual impairment, and between the full vision and no vision conditions, may reflect a more cautious walking strategy and adaptive changes employed to use the foot to probe the ground for haptic exploration.

homunculus photo courtesy of : http://joecicinelli.com/homunculus-training/

The information you have been waiting for. How do you facilitate a muscle? How do you defacilitate a muscle? Do you already know how? Do you know the mechanism?

Fear not… In this weeks Neuromechanics, Dr Waerlop simplifies the function of Golgi Tendon Organs. Clinical correlations are made throughout the presentation with his usual sense of humor. Neuro and foot geeks around the world are rejoicing…

Wow, we really are geeks!