If you are a sprinter, how you load the forefoot bipod might be a variable for speed or injury. Tendons can change their cross sectional area, if you load them.

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Of course this article is not exclusive for sprinters, it pertains to any running sport, even endurance.

Maximum isometric force had increased by 49% and tendon CSA by 17% !
Tendons can change their cross sectional area, if you load them.

Here I show lateral forefoot loading in a heel raise, and a medial forefoot loading in heel raise. This has to be part of the discovery process outlined below. Forefoot types will play into the loading choice, and unequal strength of the medial or lateral calf compartment will also play into the loading choice made. Where do you need to put your strength ? And is the forefoot competent to take that loading challenge ? Meaning, do they have a forefoot valgus? A forefoot supinatus ? These things matter. If you are a sprinter, how you load the forefoot bipod might be a variable of foot type, asymmetrical posterior compartment strength, or foot strike pattern in the frontal plane (search our blog for cross over gait and glute medius targeting strategies for step width) ,or a combination of several or all of the above. These things matter, and why and where you put your strength matters, if you are even aware of where and how you are putting the loads, and why of course. Of course, then there are people like the recent Outside online article that says how you foot strike doesn’t matter, but it does matter. But of course, if you do not know the things we have just mentioned, it is easy to write such an article.

Isometrics are useful, they have their place. In a recent podcast we discussed the place and time to use isometrics, isotonics, eccentrics and concentrics.
One of the goals in a tendinopathy is to restore the tendon stiffness. Isometrics are a safe way to load the muscle tendon complex without engaging a movement that might have to go through a painful arc of movement. With isometrics here is neurologic overspill into the painful arc without having to actually go there.
The key seems to be load. More load seems to get most people further along. Remember, the tendon is often problematic because it is inflammed and cannot provide a stiffness across its expanse. Heavy isometric loading seems to be a huge key for most cases. But, we have to say it here, not everyone fits this mold. Some tendons, in some people, will respond better to eccentrics, and strangely enough, some cases like stretching (perhaps because this is a subset of an eccentric it seems or because there is a range of motion issue in the joint that is a subset of the problem). Now the literature suggests that stretching is foolish, but each case is unique all in its own way, and finding what works for a client is their medicine, regardless of what the literature and research says.
Finding the right load for a given tendon and a right frequency of loading and duraction of loading is also case by case specific. Part of finding the right loading position is a discovery process as well, as noted in the photos above. Finding the fascicles you want to load, and the ones you do not want to load (painful) can be a challenging discovery process for you and your client. Finding the right slice of the pie to load, and the ones not to load takes experimentation. When it is the achilles complex, finding the safe However, if one is looking for a rough template to build from, brief, often, heavy painfree loads is a good template recipe to start with.

Here, in this Geremia et al article, "ultrasound was used to determine Achilles tendon cross-sectional area (CSA), length and elongation as a function of plantar flexion torque during voluntary plantar flexion."
They discovered that, "At the end of the training program, maximum isometric force had increased by 49% and tendon CSA by 17%, but tendon length, maximal tendon elongation and maximal strain were unchanged. Hence, tendon stiffness had increased by 82%, and so had Young’s modulus, by 86%.

Effects of high loading by eccentric triceps surae training on Achilles tendon properties in humans. Jeam Marcel Geremia, Bruno Manfredini Baroni, Maarten Frank Bobbert, Rodrigo Rico Bini, Fabio Juner Lanferdini, Marco Aurélio Vaz
European Journal of Applied Physiology
August 2018, Volume 118, Issue 8, pp 1725–1736

Pod 136: Part 2: Head over Foot? Where should we put our COM (center of mass)?


This podcast (135) and its soon to launch follow up podcast (136), as the intro explains, comes at the tail end of a series of thought debates between Shawn and Ivo with some folks who have a different view point.  While the debate is unsettled because there is not sufficient research to support one side, we feel the research leans towards our side of things.  However, as the debates went on, it became clear to us that both parties were approaching the debate from a different metric to gauge each party's beliefs.  We outline this in the introduction and then more forward into our dialogue.  We hope you find this a productive thought experiment.

Key words: cross over gait, head over foot, HOF, gait, gait analysis, COM, COP, center of mass, center of pressure, step width, sprinting, symmetry, running injuries

Links to find the podcast:

iTunes page: https://itunes.apple.com/us/podcast/the-gait-guys-podcast/id559864138?mt=2

Direct Download: http://traffic.libsyn.com/thegaitguys/pod_136final.mp3

Permalink URL: http://thegaitguys.libsyn.com/pod-136-part-2-head-over-foot-where-should-we-put-our-com-center-of-mass

Libsyn URL:http://directory.libsyn.com/episode/index/id/6586622


Our Websites:
www.thegaitguys.com

summitchiroandrehab.com doctorallen.co shawnallen.net

Our website is all you need to remember. Everything you want, need and wish for is right there on the site.
Interested in our stuff ? Want to buy some of our lectures or our National Shoe Fit program? Click here (thegaitguys.com or thegaitguys.tumblr.com) and you will come to our websites. In the tabs, you will find tabs for STORE, SEMINARS, BOOK etc. We also lecture every 3rd Wednesday of the month on onlineCE.com. We have an extensive catalogued library of our courses there, you can take them any time for a nominal fee (~$20).

Our podcast is on iTunes and just about every other podcast harbor site, just google "the gait guys podcast", you will find us.

Pod 135: Part 1: Head over Foot? Where should we put our COM (center of mass)?

Key words: cross over gait, head over foot, HOF, gait, gait analysis, COM, COP, center of mass, center of pressure, step width, sprinting, symmetry, running injuries

This podcast (135) and its soon to launch follow up podcast (136), as the intro explains, comes at the tail end of a series of thought debates between Shawn and Ivo with some folks who have a different view point.  While the debate is unsettled because there is not sufficient research to support one side, we feel the research leans towards our side of things.  However, as the debates went on, it became clear to us that both parties were approaching the debate from a different metric to gauge each party's beliefs.  We outline this in the introduction and then more forward into our dialogue.  We hope you find this a productive thought experiment.
 

Links to find the podcast:

iTunes page: https://itunes.apple.com/us/podcast/the-gait-guys-podcast/id559864138?mt=2

Direct Download: http://traffic.libsyn.com/thegaitguys/pod_135final.mp3

Permalink URL: http://thegaitguys.libsyn.com/pod-135-part-1-head-over-foot-where-should-we-put-our-com-center-of-mass

Libsyn URL: http://directory.libsyn.com/episode/index/id/6309104


Our Websites:
www.thegaitguys.com

summitchiroandrehab.com doctorallen.co shawnallen.net

Our website is all you need to remember. Everything you want, need and wish for is right there on the site.
Interested in our stuff ? Want to buy some of our lectures or our National Shoe Fit program? Click here (thegaitguys.com or thegaitguys.tumblr.com) and you will come to our websites. In the tabs, you will find tabs for STORE, SEMINARS, BOOK etc. We also lecture every 3rd Wednesday of the month on onlineCE.com. We have an extensive catalogued library of our courses there, you can take them any time for a nominal fee (~$20).

Our podcast is on iTunes and just about every other podcast harbor site, just google "the gait guys podcast", you will find us.

Walking and Running Require Greater Effort from the Ankle than the Knee Extensor Muscles.

 

Attached is an older video from a few years back , it is very similar in execution to the heel-rise ball squeeze exercise which is the precursor to this more functional engagement as shown in this video today.  


The important premise is that you have to have command of the entire posterior compartment if you are to get safe, effective, efficient and adequate ankle plantarflexion. As we have discussed many times, if you do not have the requisite skills as shown in this video you are in trouble and ankle sprains and other functional pathologies are not unlikely to visit you.  Additionally, without requisite posterior compartment endurance and an ability to engage what I like to refer to as "top end" strength in the heel rise is an asymmetrial loading issue and can lead to compensatory adaptations up the kinetic chain. Make no mistake, the load will go somewhere, and thus the work will be done somewhere. In this video you should be able to clearly see and understand that one must be able to achieve top end posturing and have command of lateral and medial forefoot loading responses and challenges if clean forward function and power is to be achieved, and injuries from extremes of motion medially and laterally are to be avoided. Furthermore, as eluded to here and in several of our podcasts (and in the study included below), an inability to achieve top end posturing will lead to changes in forefoot loading, may spill over into endurance challenges prematurely in the posterior mechanism, and create changes in the timing of the gait cycle (things like premature or delayed heel rise, premature or delayed forefoot loading, recruitment of other components of the posterior chain just to name a few). This parsing and sharing of loads and responsibilities is laid out in the Kulmala study referenced today. The study could be extrapolated to say, I believe, that particularly in sprinting, a failure to achieve top end heel rise through effective posterior mechanism contraction, will change the load sharing between the posterior compartment and the quadriceps. After all, if the calf is weak, the ankle is not in as much plantarflexion, this could mean more knee flexion and thus raise demands on the quadriceps, logically changing knee mechanics.  This is exactly why we spend so much time at every patient visit looking for full range of motion at the joints and then determine the skill, endurance and strength of the associated muscles in supporting that range. Then, of course, comparing this function to the opposite limb.  Symmetry is not everything, but it is definitely a major factor in safe efficient and injury free locomotion.

* Please give great thought to the part in the video where I discuss the drop phase in jumping. All too often we at looking for the propulsive mechanics and forget that a failure there will also be represented during the adaptive phase. Ankle sprains rarely occur from propulsive pushing off, they occur from a failure to properly reacquaint the foot to the ground on the following step.
-Dr. Shawn Allen, one of the gait guys.

In this study the authors noted:
"During walking, the relative effort of the ankle extensors was almost two times greater compared with the knee extensors. Changing walking to running decreased the difference in the relative effort between the extensor muscle groups, but still, the ankle extensors operated at a 25% greater level than the knee extensors. At top speed sprinting, the ankle extensors reached their maximum operating level, whereas the knee extensors still worked well below their limits, showing a 25% lower relative effort compared with the ankle extensors."

And concluded that:
"Regardless of the mode of locomotion, humans operate at a much greater relative effort at the ankle than knee extensor muscles. As a consequence, the great demand on ankle extensors may be a key biomechanical factor limiting our locomotor ability and influencing the way we locomote and adapt to accommodate compromised neuromuscular system function."

Med Sci Sports Exerc. 2016 Nov;48(11):2181-2189. Walking and Running Require Greater Effort from the Ankle than the Knee Extensor Muscles. Kulmala JP1, Korhonen MT, Ruggiero L, Kuitunen S, Suominen H, Heinonen A, Mikkola A, Avela J.
https://www.ncbi.nlm.nih.gov/pubmed/27327033

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Notice the differences in running (top) vs sprinting (bottom) activation patterns?

This picture (along with the MIchaud muscular firing pattern ones) are becoming some of my favorite ones to talk about. I just stare at them and look for differences and similarities. 

Check out that the abs do not seem to fire in running (in this study at least), but do in sprinting. Note also that most muscles fire longer (and we wil assume harder) during sprinting. Also check out the peroneals, which fire just as the foot touches down in sprinting, probably to make up for the instrinsics not firing, and assist in creating a rigid lever for push off. 



from: Mann et al 1986

Usain… Again!!! How good are your powers of observation?

Take a look at this video again. Yes, we have shown it many times before. It is from a 2001 race in Monaco.

These are all incredible athletes. What can we note about the fastest of the fast?

  • Most of them have excellent hip extension (ok, the gent immediately to Usain’s right does not appear to be optimal)
  • the fastest of the pack have a upright head posture with the neck neutral or in slight extension (gents in lanes 1, 3 and 6; notice the head forward posture of the others)
  • minimal heel rebound (see our last post on this here)
  • minimal torso motion (note the increased torso motion  with arm swing of the gents in lanes 1, 3, 4 and 5)
  • symmetrical hip flexion, with the thigh parallel or nearly parallel to the ground in float phase
  • what else?

Watch it a few more times. It took us a while too…

Really, go watch it again…

Did you see it?

Watch the vertical oscillation of the runners. At this level (or any level for that matter), outside of improving biomechanics and neuromechanics, there are really only a few things you can do to run faster. One is to have a faster cadence and another is to have a longer stride length. You can control both, but if not done concurrently, one gets better at the expense of the other.

If your cadence is slower and you try and increase stride length, you increase your vertical oscillation (ie: how much you bounce up and down). Note the handrail at the far side of the track. It makes a convenient marker for vertical oscillation. Watch this bar and watch the video again. Usain and the gent in lane 6 (Nesta Carter) have little vertical oscillation compared to the rest of the pack. Note also the close finish. difficult to say if Usain’s knee or Carters foot crossed 1st. Usiain’s time was 9.88 and Nesta’s 9.90.

Decreased cadence = Increased vertical oscillation = Less horizontal motion = Slower speeds

How about watching this video a few more times and telling us what else is up?

The Gait Guys. We are trying to help you improve your powers of observation while stretching your mind. Are we succeeding? We hope so!

Ivo and Shawn

Ankle Dorsiflexion: Even in sprinters who land on the forefoot often heel strike, a retrograde strike if you will.

Many people think of heel strike followed by midfoot/tripod contact phase followed by ankle dorsiflexion, aka ankle rocker.  Heel strike is normal in the walking gait cycle. In some runners, depending on foot type, strength, flexibilty and several other factors, heel strike may be considered normal and may be essential for normal injury free mechanics. However, in recent years we tend to see the media and research investigate a midfoot or forefoot strike pattern. If you have been here with us on TGG for a year or 2-3 you will know we are big advocates of a midfoot strike pattern for several reasons which we will not go into again in this article. (Feel free to SEARCH our blog for MIDFOOT strike articles).  

However, one rarely sees anyone or any source talking about the retrograde heel contact when forefoot strike patterns are used.  Here, in this video, you can see several of these top level athletes who are trying to go forward at top end speed, but who are tapping the heel down on many loading responses. This can be thought of as a retrograde movement and could in a biomechanical way of thinking be considered non-productive. In other words, they are trying to move forward and yet the heel is touching down which is a backwards movement. This point can be argued but that is not the point of this article. The point that we are trying to make is that in order to drop the heel down, and especially if the heel touches, that the runner had better have sufficient ankle rocker/dorsifleixon otherwise the arch may be asked to collapse via excessive pronation (to perform the heel tap) which will drive an internal spin movement when the leg is supposed to be externally rotating to a rigid supinated foot for propulsive toe off. This negative scenario is a huge power leak for a sprinter, or any runner for that matter when they are ramping up speed.  

So, why does this happen ?  Well, for some it can help to load the posterior mechanism, the gastrocsoleus-achilles complex for conservation and power conversion.  It also enables more hip extension and thus more gluteal function. Longer stride means more efficient and greater arm swing which is a huge accessory power source for a sprinter. This also lengthens the stride, they feed off of each other. There are many benefits, if you have sufficient ankle rocker range in the ankle to begin with.  In some runners who do not have the requisite ankle rocker range, you may often see the increased foot progression angle and external limb spin and/or the dreaded adductor twist of the heel (aka  abductory twist of the foot).  These are strategies to get more hip extension and more gluteal function without finding it via the ankle dorsiflexion, where you want to see it.  Remember, the body is a brilliant compensatory and substituter. If the body cannot find a range at one joint it will find it at the next proximal or distal joint. And when that loss is at the ankle, motor patterns options dictate you either find it at foot pronation or hip extension.

Maybe, just maybe we should have called this blog article “Can you hold the foot tripod all the way through the stance phase, even through retrograde heel touch down ? If you cannot, trouble could be on the horizon. ”  But that is a really dumb title.  

Shawn and Ivo

the gait guys

Some Biomechanical Facts on Oscar Pistorius: 400 m London Olympic Games

Following Saturday’s 400m men’s preliminary heats Jere Longman’s wrote an article in the NYTimes entitled “Pistorius Advances to Semifinals”. In it were some interesting facts. Here is the link to the article. 

Ever since Pistorius’s shut out from the Beijing Olympics scientific and legal debate has continued about whether his prosthetic legs gave him an unfair advantage over sprinters using their natural legs. However, as we all knew, this time around would different in London 2012. Competing on carbon-fiber prosthetics called Cheetahs, Pistorius was going to get his chance and in the process further the debate on what is considered able and disabled.

Prior to Beijing the I.A.A.F. said Pistorius’ carbon-fiber blades violated its ban against springs or wheels that gave an athlete a competitive edge over able bodied athletes. The prosthetic legs allowed him to run as fast as elite sprinters while consuming less energy, the governing body concluded. None the less, the debate has continued over the past few years since Beijing pertaining to where to draw the line between fair play and the right to compete. In 2009 in The Journal of Applied Physiology a study concluded that Pistorius could take his strides more rapidly and with more power than a sprinter on biological legs.

An acquantance of ours who we talk to from time to time, Professor Peter Weyand at SMU Locomotor Performance Laboratory in 2009 looked at Oscar Pistorius-type carbon fiber Cheetah blades a little more closely. In his study (referenced below), in the Journal of Applied Physiology, he conducted three tests of functional similarity between an amputee sprinter and competitive male runners with intact limbs: the metabolic cost of running, sprinting endurance, and running mechanics. What he found was:

  • the mean gross metabolic cost of transport of the amputee sprint subject was only 3.8% lower than mean values for intact-limb elite distance runners and 6.7% lower than for subelite distance runners but 17% lower than for intact-limb 400-m specialists
  • the speeds that the amputee sprinter maintained for six all-out, constant-speed trials to failure were within 2.2 (SD 0.6)% of those predicted for intact-limb sprinters.
  • at sprinting speeds of 8.0, 9.0, and 10.0 m/s, the amputee subject had longer foot-ground contact times ,shorter aerial and swing times and lower stance-averaged vertical forces than intact-limb sprinters [top speeds = 10.8 vs. 10.8 (SD 0.6) m/s].

Weyand concluded that running on modern, lower-limb sprinting prostheses appears to be physiologically similar but mechanically different from running with intact limbs.

Longman’s article listed some of the other facts that have come up in recent years, facts that led to the eventual acceptance of Pistorius in London 2012’s Olympic events.  We have not captured these references specifically (yet, but we will) but in the mean time to keep this blog article timely, lets look at some of the other facts that Longman mentioned in his NYTimes article:

  • While calf muscles generate about 250 percent energy return with each strike of the track, propelling a runner forward, Pistorius’s carbon-fiber blades generate only 80 percent return, Gailey said.
  • Given that Pistorius has no feet or calves, he must generate his power with his hips, working harder than able-bodied athletes who use their ankles, calves and hips, Gailey said.
  • And because the blades are narrow and Pistorius essentially runs on his tip toes, he pops straight up out of the blocks instead of driving forward in a low, aerodynamic position for the first 30 or 35 meters, making him more susceptible to wind resistance, Gailey said.
  • Compared with runners with biological feet, Pistorius also must work harder against centrifugal force in the curves, and his arms and legs tend to begin flailing more in the homestretch, costing him valuable time, Gailey said. His stride is not longer than other runners, as many presume, Gailey said. “It’s not like he’s bouncing high with a giant spring,” Gailey said.
  • The blades “basically allow him to roll over the foot and get a little bounce,” Gailey said, adding: “The human foot operates like a spring, and his feet operate like a spring. But the human foot produces more power than the blades do.”

There is an abundance of interesting information here. We will likely return to some of these topics and facts in the future, but in the meantime we say that everyone has their own demons and deficits. We all have injuries and limitations we have to cope with, in life and in sport. So where the line gets drawn will always be a blurred. This debate on this specific case with Pistorius could go on for years and never reach an agreeable conclusion as to a fair playing field. So, let the games begin and may the best man or woman win, with his or her demons and deficits in tow.  Good work Oscar. Thanks for the inspiration.

Shawn and Ivo, The Gait Guys

____________________________

We found 3 other journal articles on Pubmed on Oscar.

  1. Enhancing disabilities: transhumanism under the veil of inclusion? Van Hilvoorde I, Landeweerd L.   Disabil Rehabil. 2010;32(26):2222-7.

  2. Oscar Pistorius, enhancement and post-humans. Camporesi S. J Med Ethics. 2008 Sep;34(9):639.

  3. By designing ‘blades’ for Oscar Pistorius are prosthetists creating an unfair advantage for Pistorius and an uneven playing field? Chockalingam N, Thomas NB, Smith A, Dunning D. Prosthet Orthot Int. 2011 Dec;35(4):482-3.

  4. J Appl Physiol. 2009 Sep;107(3):903-11. Epub 2009 Jun 18.

    The fastest runner on artificial legs: different limbs, similar function?