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: 


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

Gait Guys online /download store:


Today’s show notes:


1. The First Truly Bionic Hand


“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


Clinical Biomechanics, Jan 2013

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


  • 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.

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”


  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 : )

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!