Podcast 101: Physics of falling & running.

Podcast 101: Physics of Falling & Running
Plus: calf strengthening problems, odometer neurons help you find your way, Chi running and more !

Show Sponsors:
newbalancechicago.com
rocktape.com

Other Gait Guys stuff

A. Podcast links:

direct download URL:http://traffic.libsyn.com/thegaitguys/pod_101fmp3.mp3

permalink URL: http://thegaitguys.libsyn.com/podcast-101

B. iTunes link:
https://itunes.apple.com/us/podcast/the-gait-guys-podcast/id559864138
C. Gait Guys online /download store (National Shoe Fit Certification & more !)
http://store.payloadz.com/results/results.aspx?m=80204
D. other web based Gait Guys lectures:
Monthly lectures at : www.onlinece.com type in Dr. Waerlop or Dr. Allen, ”Biomechanics”

-Our Book: Pedographs and Gait Analysis and Clinical Case Studies
Electronic copies available here:

-Amazon/Kindle:
http://www.amazon.com/Pedographs-Gait-Analysis-Clinical-Studies-ebook/dp/B00AC18M3E

-Barnes and Noble / Nook Reader:
http://www.barnesandnoble.com/w/pedographs-and-gait-analysis-ivo-waerlop-and-shawn-allen/1112754833?ean=9781466953895

https://itunes.apple.com/us/book/pedographs-and-gait-analysis/id554516085?mt=11

-Hardcopy available from our publisher:
http://bookstore.trafford.com/Products/SKU-000155825/Pedographs-and-Gait-Analysis.aspx

Show Notes:

‘Odometer neurons’ encode distance traveled and elapsed time
http://www.eurekalert.org/pub_releases/2015-11/cp-ne102815.php#.Vj5xCP01e5w.facebook

Snap on shoehttp://www.digitaltrends.com/cool-tech/minimal-shoe-3d-printed-programmable-fabric-snaps-into-shape/

Physics of falling/runninghttps://www.newscientist.com/article/dn28246-physics-of-falling-says-professional-athletes-are-running-wrong/

Foot strike and (pre)positioning ?
http://www.runnersworld.com/sweat-science/where-should-your-feet-land-while-running

Non-local fatigue
http://www.runnersworld.com/sweat-science/the-mystery-of-nonlocal-fatigue

Chi running, less injuries?http://www.runresearchjunkie.com/chi-running-did-not-lead-to-less-injuries/  

CAlf strength screen?http://thebarbellphysio.com/2015/10/09/calf-strength-assessment/stupid screen 

http://blog.brainfacts.org/2013/08/human-grid-cells/#.Vk-TemSrQ_V

http://www.nature.com/neuro/journal/v16/n9/abs/nn.3466.html

Podcast 67: Biotech of Running’s Future, Rothbart’s Foot, 100 Ups

A. Link to our server:

Direct Download:

http://traffic.libsyn.com/thegaitguys/pod_67finals.mp3

Permalink: http://thegaitguys.libsyn.com/podcast-67

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:

The cyborg era begins next week at the World Cup
 
The One Exercise That Just Might Change Your Running Forever
 

What Foot Strike Photos From 10K Olympic Trials Say About Barefoot Running by 

Podcast 67: Biotech of Running’s Future, Rothbart’s Foot, 100 Ups

A. Link to our server:

Direct Download:

http://traffic.libsyn.com/thegaitguys/pod_67finals.mp3

Permalink: http://thegaitguys.libsyn.com/podcast-67

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:

The cyborg era begins next week at the World Cup
 
The One Exercise That Just Might Change Your Running Forever
 

What Foot Strike Photos From 10K Olympic Trials Say About Barefoot Running by 

More on EVA foam, impact loading behaviors, and adding shoe inserts.

A few weeks ago we wrote about some thoughts on the maximalist shoe foam trend and how it is possible that more foam could mean alterations in impact loading behaviors that could lead to problems (note we used the word could, and not will).  If there are pre-existing proprioceptive deficits in a limb these issues most likely will rise to the surface. 

The EVA foam in shoes is primarily used to absorb forces via air flow through interconnected air cells in the EVA during shoe deformation under body-weight. When the shoe has seen a finite number of compressive cycles the air cells collapse and the EVA can compact on itself leaving the shoe with an negatively impacting area of compression to fall into.  Shock absorption may be impacted and possibly lead to injury.

The Robbins study we discussed a few weeks ago (link) suggested that the reduction of impact moderating behaviour is 

Reduction of impact-moderating behavior is a response to loss of stability induced by soft-soled cushioned shoes: Humans reduce impact-moderating behavior in direct relation to increased instability.This is presumably an attempt to achieve equilibrium by obtaining a stable, rigid support base through compression of sole materials. Humans reduce impact-moderating behavior, thereby amplifying impact, when they are convinced that they are well protected by the footwear they are wearing. 

These were important points but we wanted to bring to your awareness of the component of the shoe you may have not thought of to this point, the foam foot bed that comes with the shoe, or ones you might add to the shoe  yourself post-purchase. With what we have just taught you in our last blog post and this blog post, we will let you make the connection we are suggesting you be aware of when it come to more foam, changes in foam as the shoes and inserts degrade and impaired impact loading behaviors.

There are just 3 brief study summaries here, take the time to read them and read between the lines now that we have educated you a little better in how to think about them.

Shawn and Ivo

J Appl Biomech. 2007 May;23(2):119-27.

Effects of insoles and additional shock absorption foam on the cushioning properties of sport shoes.

The purpose of this study was to investigate the effects of insoles and additional shock absorption foam on the cushioning properties of various sport shoes with an impact testing method. 

The results of this study seemed to show that the insole or additional shock absorption foam could perform its shock absorption effect well for the shoes with limited midsole cushioning. 

Further, our findings showed that insoles absorbed more, even up to 24-32% of impact energy under low impact energy. 

It seemed to indicate that insoles play a more important role in cushioning properties of sport shoes under a low impact energy condition.

_______

Biomed Mater Eng. 2006;16(5):289-99.

Role of EVA viscoelastic properties in the protective performance of a sport shoe: computational studies.

 Using lumped system and finite element models, we studied heel pad stresses and strains during heel-strike in running, considering the viscoelastic constitutive behavior of both the heel pad and EVA midsole. In particular, we simulated wear cases of the EVA, manifested in the modeling by reduced foam thickness, increased elastic stiffness, and shorter stress relaxation with respect to new shoe conditions. Simulations showed that heel pad stresses and strains were sensitive to viscous damping of the EVAWear of the EVA consistently increased heel pad stresses, and reduced EVA thickness was the most influential factor, e.g., for a 50% reduction in thickness, peak heel pad stress increased by 19%. We conclude that modeling of the heel-shoe interaction should consider the viscoelastic properties of the tissue and shoe components, and the age of the studied shoe.

________________

J Biomech. 2004 Sep;37(9):1379-86.

Heel-shoe interactions and the durability of EVA foam running-shoe midsoles.

A finite element analysis (FEA) was made of the stress distribution in the heelpad and a running shoe midsole, using heelpad properties deduced from published force-deflection data, and measured foam properties. The heelpad has a lower initial shear modulus than the foam (100 vs. 1050 kPa), but a higher bulk modulus. The heelpad is more non-linear, with a higher Ogden strain energy function exponent than the foam (30 vs. 4). Measurements of plantar pressure distribution in running shoes confirmed the FEA. The peak plantar pressure increased on average by 100% after 500 km run. Scanning electron microscopy shows that structural damage (wrinkling of faces and some holes) occurred in the foam after 750 km run. Fatigue of the foamreduces heelstrike cushioning, and is a possible cause of running injuries.

 

More on EVA foam, impact loading behaviors, and adding shoe inserts.

A few weeks ago we wrote about some thoughts on the maximalist shoe foam trend and how it is possible that more foam could mean alterations in impact loading behaviors that could lead to problems (note we used the word could, and not will).  If there are pre-existing proprioceptive deficits in a limb these issues most likely will rise to the surface. 

The EVA foam in shoes is primarily used to absorb forces via air flow through interconnected air cells in the EVA during shoe deformation under body-weight. When the shoe has seen a finite number of compressive cycles the air cells collapse and the EVA can compact on itself leaving the shoe with an negatively impacting area of compression to fall into.  Shock absorption may be impacted and possibly lead to injury.

The Robbins study we discussed a few weeks ago (link) suggested that the reduction of impact moderating behaviour is 

Reduction of impact-moderating behavior is a response to loss of stability induced by soft-soled cushioned shoes: Humans reduce impact-moderating behavior in direct relation to increased instability.This is presumably an attempt to achieve equilibrium by obtaining a stable, rigid support base through compression of sole materials. Humans reduce impact-moderating behavior, thereby amplifying impact, when they are convinced that they are well protected by the footwear they are wearing. 

These were important points but we wanted to bring to your awareness of the component of the shoe you may have not thought of to this point, the foam foot bed that comes with the shoe, or ones you might add to the shoe  yourself post-purchase. With what we have just taught you in our last blog post and this blog post, we will let you make the connection we are suggesting you be aware of when it come to more foam, changes in foam as the shoes and inserts degrade and impaired impact loading behaviors.

There are just 3 brief study summaries here, take the time to read them and read between the lines now that we have educated you a little better in how to think about them.

Shawn and Ivo

J Appl Biomech. 2007 May;23(2):119-27.

Effects of insoles and additional shock absorption foam on the cushioning properties of sport shoes.

The purpose of this study was to investigate the effects of insoles and additional shock absorption foam on the cushioning properties of various sport shoes with an impact testing method. 

The results of this study seemed to show that the insole or additional shock absorption foam could perform its shock absorption effect well for the shoes with limited midsole cushioning. 

Further, our findings showed that insoles absorbed more, even up to 24-32% of impact energy under low impact energy. 

It seemed to indicate that insoles play a more important role in cushioning properties of sport shoes under a low impact energy condition.

_______

Biomed Mater Eng. 2006;16(5):289-99.

Role of EVA viscoelastic properties in the protective performance of a sport shoe: computational studies.

 Using lumped system and finite element models, we studied heel pad stresses and strains during heel-strike in running, considering the viscoelastic constitutive behavior of both the heel pad and EVA midsole. In particular, we simulated wear cases of the EVA, manifested in the modeling by reduced foam thickness, increased elastic stiffness, and shorter stress relaxation with respect to new shoe conditions. Simulations showed that heel pad stresses and strains were sensitive to viscous damping of the EVAWear of the EVA consistently increased heel pad stresses, and reduced EVA thickness was the most influential factor, e.g., for a 50% reduction in thickness, peak heel pad stress increased by 19%. We conclude that modeling of the heel-shoe interaction should consider the viscoelastic properties of the tissue and shoe components, and the age of the studied shoe.

________________

J Biomech. 2004 Sep;37(9):1379-86.

Heel-shoe interactions and the durability of EVA foam running-shoe midsoles.

A finite element analysis (FEA) was made of the stress distribution in the heelpad and a running shoe midsole, using heelpad properties deduced from published force-deflection data, and measured foam properties. The heelpad has a lower initial shear modulus than the foam (100 vs. 1050 kPa), but a higher bulk modulus. The heelpad is more non-linear, with a higher Ogden strain energy function exponent than the foam (30 vs. 4). Measurements of plantar pressure distribution in running shoes confirmed the FEA. The peak plantar pressure increased on average by 100% after 500 km run. Scanning electron microscopy shows that structural damage (wrinkling of faces and some holes) occurred in the foam after 750 km run. Fatigue of the foamreduces heelstrike cushioning, and is a possible cause of running injuries.

 

Podcast 56: Crawling, Neurodevel. & Foot Strike

A. Link to our server:

Direct Download: 

http://traffic.libsyn.com/thegaitguys/pod_57_final.mp3

Permalink: http://thegaitguys.libsyn.com/podcast-56-crawling-neurodevel-foot-strike

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

Human quadrupedalism is not an epiphenomenon caused by neurodevelopmental malformation and ataxia.  

” a re-emergence of the ancestral diagonal QL, and (3) it may spontaneously emerge in humans with entirely normal brains, by taking advantage of neural networks such as central pattern generators that have been preserved for about 400 million years.”

References:

Front Neurol. 2012 Oct 25;3:154. doi: 10.3389/fneur.2012.00154. eCollection 2012. Karaca S1, Tan MTan U. Human quadrupedalism is not an epiphenomenon caused by neurodevelopmental malformation and ataxia.
2)  selectively removing torsions ? bunions ?  
FDA Panel Mulls Technique That Creates Babies Using DNA of 3 People
http://foxnewsinsider.com/2014/02/25/fda-panel-mulls-technique-creates-babies-using-dna-3-people
3) A Crazy Oculus Rift Hack Lets Men and Women Swap Bodies

http://www.wired.com/design/2014/02/crazy-oculus-rift-experiment-lets-men-women-swap-bodies/

“Minimum effective dose: Why less is more” – via Farnam Street blog. True for manual therapy, for sure. Lighten up, hack nervous system instead of trying to force structure to comply.http://www.farnamstreetblog.com/2014/02/the-minimum-effective-dose-why-less-is-more/
6) Unpowered Treadmills

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

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”

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.