Normal walking and running have a certain degree of vertical oscillation, but we do not want too much

Normal walking and running have a certain degree of vertical oscillation, but we do not want too much, we want the body to move along mostly horizontal path but we do need some dampening of impact loads. We do not want to waste too much energy bouncing up and down. This is mitigated quite a bit by hip and knee flexion, the knee is well positioned to do this the easiest in many cases. Pronation and ankle dorsiflexion do dampen loads as well.

Ivo and I just recorded a class on leg length discrepancies. Here are some factors to keep in mind if there is even the smallest leg length discrepancy, anatomic or functional.

-the short leg may hyperextend at the knee , externally rotate at the hip, as well as supinate the foot (this supination is relative ankle plantarflexion, which can set up increased protective tone in calf complex and reduced strength and exposure to anterior compartment).

-the long leg side may knee flex , internally rotate at the hip, and as well as pronate at the foot (this is relative ankle Dorsiflexion)

Both of these scenarios can be going on at the same time on either leg, or it can be only on one leg. We are not perfectly symmetrical organisms, so these things can set up to help us run and walk more effortlessly, to compensate to get the head and neck properly positioned (normalizing the visual and vestibular centers on the horizon) for balance and movement through the 3 cardinal planes, and to compensate around challenging anatomy or biomechanics.

This is a complex machine, with infinite abilities to compensate and cope. But what we see is the compensation, not the problem. The joint range losses in one joint, the excesses in another, the weakness in one area, the over protection in another, the failure to tolerate loads in another, are all ways of coping and keeping us moving, . . . . . . but sometimes at a cost. . . . . pain.

shawn and ivo, the gait guys

Loss of terminal knee extension: How quickly can you process the facts ?

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Some quick thoughts that must go through your mind on your examination. These thoughts must be ingrained, so that you can quickly juggle the other issues you client is coming in with that may very likely be related to the loss of left knee terminal extension.

more knee flexion may likely mean more ankle dorsiflexion , and that means more more anterior shin compartment strength is necessary to stop a quick progression to the forefoot (consider their clinical symptoms), this may mean pronation occurs more quickly (consider their clinical symptoms), it may mean more abrupt quadriceps loading since the loading does not start in more reasonable knee extension which means the quad is short now and that means increased patellofemoral compression possibilities (consider their clinical symptoms), this may mean more hip flexion on initiation of stance phase (consider their clinical symptoms), this may lead to more anterior pelvis tilt posturing and thus increased lordosis (consider their clinical symptoms), this flexed knee means that the leg is shorter which will through off pelvis symmetry (consider their clinical symptoms), this may mean more work for the contralateral hip abductors (consider their clinical symptoms), this may mean more frontal plane pelvis drift to the short leg side (consider their clinical symptoms), it will also mean 2 different step lengths which means 2 different hip extension patterns which means 2 different heel rises, and it will likely mean altered arm swing on both sides which can create changes into thoracic rotation (and of course the cervical spine sits on top of that) etc etc etc, so consider their clinical symptoms . . .

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just wanted to quickly rattle off how fast your brain must juggle things, otherwise your exam is going to be knee-centered and tunnel visioned. Keep in mind, your client may not even have knee complaints, perhaps one or more of the above. But this is a perfect example of why you must examine the WHOLE client.

Perhaps this gives you even deeper understanding (combined with yesterdays "parallax binocular vision 2D post" as to why we will not give online corrective homework or consultations. There is just no way all of these things can be considered over video, Skype, Zoom or anything of the sort. Gait analysis must be done in person and encompass a hands on exam, if you do not want to miss something possible critically important, in our opinion, for what that is worth.

Shawn Allen, the other gait guy

#kneeextension, #gait, #gaitanalysis, #gaitproblems, #gaitanalysis, #gaitcompensations, #correctiveexercises, #thegaitguys

What do the hip flexors have to do with the knee extensors ?


"It is not about your test, it is what your client displays in your test that matters. They will try to find a way. The load has to go somewhere, and they will find a place to put it, they always do. Finding out how your client cheats, compensates, recruits and fails is the value of the assessment."

This is just a small example of how I approach a client through small assessment window.
As best as I am able, knowing the absolute limitations of a supine examinations translation to vertical loading, I will approach a client's ability to stabilize in all 3 planes of movement. Today, i will micro-dissect a thought process.

The straight leg resistance test (SLR):
just a few incomplete thoughts on a SAGITTAL perspective (so as to avoid writing a book).
I will do it looking at **pelvis posture (anterior, posterior, oblique), lumbar spine posture (incr/decr lordosis), if they can keep their knee locked in a position, does the pelvis rotate, do they want to deviate into internal or external rotation at the hip, do they plantar or dorsiflex their ankle or toes. Lots to see here in how a client will recruit, and this is just a small snapshot of things they might do. Yes, head position, arm position were left out , again, to avoid a longer post today.
I will add consistent (as best as possible) resistance in the SLR test , with full locked knee, at hip 30, 45 and then full straight leg SLR (at the client's hamstring tension limit), then again at 45 degree knee lock with partial hip flexion, 90 degree hip and knee. I am changing loading vectors frequently to see if their is a directional loading failure. I am looking for their ability to provide ample resistance, and how they might cheat (see above).
But here is how my mind works through the test on the most basic level, which will give me insight on the above cheats** the client may employ.
* In the MOST SIMPLEST thought of the assessment, can they EFFECTIVELY stabilize the pelvis to the lumbar spine, can they stabilize the femur into the pelvis, can they stabilize the tibia onto the femur? It is how they choose to engage the system that matters, and that might be partly why their "Screen" shows up shoddy and may be a window into their pain.
The question is, if they fail, where are they failing and what tissues are overburdened or over protecting ? Where is the load, and where NOT is the load, going ?

"It is not about your test, it is what your client displays in your test that matters. They will try to find a way. The load has to go somewhere, and they will find a place to put it, they always do. Finding out how your client cheats, compensates, recruits and fails is the value of the assessment. This is how you need to be thinking when you perform many of the mostly useless orthopedic tests in the textbooks.

This is key,
a SLR screen will not show you any of this, it will just show you their range of motion, nothing more, not how they did it, what parts worked harder than other parts, and which parts are weak, injured or inhibited, for example. It is not what a client does, it is how they go about it that has the most value to you in helping them.

Today's article below is what spurred my rant today. It gives light that most already know, that everything is connected. And perhaps we can translate it into deeper thoughts for our clients, namely, what part is not doing its job, and where are they not connecting the parts, and where are they putting the loads ?

From the Ema study:
"Our findings indicate that hip flexion training results in substantial neuromuscular adaptations during knee extensions similar to those induced by knee extension training."-Ema et al.

We need a stable and strong core-spine-pelvis connection to display powerful knee extension, and, we need a stable and strong femur-pelvis connection as well. So, where is your client doing more or less of the work, and is it related to their hip, low back or knee pain? Or are they tossing it into the ankle perhaps? This is the beauty of the game we all play every day, if we are actually paying attention.

Now, remember my discussion last week about "adding strength to dysfunction" ? Where is your client going to put the load?, the answer, where they can/able. And that doesn't exactly mean where they should be putting it. Mindless prescription of corrective exercises is a real problem in my opinion.

Shawn Allen, the other gait guy.

#gait, #gaitproblems, #gaitanalysis, #correctiveexercises, #running, #hipflexors, #kneeextension, #SLR, #corestrength, #thegaitguys

Scand J Med Sci Sports. 2018 Mar;28(3):947-960. doi: 10.1111/sms.13008. Epub 2017 Nov 22.
Neuromuscular adaptations induced by adjacent joint training.
Ema R1,2, Saito I3, Akagi R1,3.

Extension Thrust Gait /Varus Thrust Gait

Getting inside Dr. Allen's head again:

Last night i was asked to watch a client's gait and assist in the case. It was clear what we were seeing what initially was an "extension thrust gait" (note: i did not video the case, the video posted here is not the client but depicts an extension thrust well). The client had gradually also developed a Varus Thrust gait, which I have written about here several times in the last 2 months. The extension exaggeration often goes with the Varus Thrust gait. The do not have to be paired, but it is easier to go into Varus at the knee if one hyperextends first. Go ahead, stand and lock one knee back and feel the tendencies to move into varus slightly. Valgus is not likely in most people unless some predisposing OA welcomes it.
My point here today, is 2 fold.
These abnormal thrust variants are subtle at the start. To be the best you can be to your client, you have to find these problems in their infancy before they become enormous joint ranges that are impossible to correct, not to mention their soft tissue, ligament, and cartilaginous derangement and maceration. In the case I saw last night we added a sole lift to the entire foot-shoe.
Why? because a client that hyperextends also eats up some of the leg length by folding the knee posteriorly. This, when combining the extension thrust, and in their case, the varus thrust as well, it causes an Anterior Pelvis dumping on that same side, this facilitates further quad loading and thus further extension knee joint drive. It is a viscous cycle. See it in the video here, there seems no way out. The knee load is retrograde. This all creates a functional short leg, furthering the viscous loop. One has to bring the ground up to the shorter leg so help them "feel" the longer leg, thus helping them find the glute to help reorient the pelvis more posterior-ward, gait more finesse of the extensor mechanism (quads mostly). Then we added some kinesio-Rock tape to the posterior knee, applying it in relative knee flexion so that there was some biofeedback as to when they were exceeding knee neutral, moving too far into extension. This sensory motor relearning is critical, without it, they will be dependent upon devices. But the time the client left, with these in hand (foot :) : 2mm sole lift, awareness of aberrant knee extension strategy and varus thrust, how to co-contract the adductors to minimize the varus thrust and a neutral pelvis posture using more glutes (to also help them engage the adductors off the new neutral pelvis), and some flexible biofeedback tape application . . . . the client left with zero extension and varus thrust........and much work to do moving forward.
You have to see these things in their infancy, and that means you have to first recognize them, know how to negotiate around the numerous complicating components of all of them, and not train them deeper into it first of all. Recognize, restore, retrain.
Ala Neil Degrasse tyson: "facts, knowledge, wisdom, insight", . . . in that order.
PS: Oh, the client also had a deeply embedded scoliosis that i had to juggle (there were 5-6 balls going here at once) that was further driving the anterior pelvis drop on the affected side into a torsional pelvis distortion pattern. But, I didn't bring that up, and what i did with that component, because i didn't want anyone brain-barfing on their computer screen. Maybe another day :)

-Dr. Allen

https://www.youtube.com/watch?v=YjRoLtP1di0

Who Rules -- The glutes or the quads? Well, it is complicated.

We have often talked about how important it is to be able to achieve terminal hip extension for an athlete, and arguably for everyone. This means one must have strength of the glutes into that terminal range so one can actually achieve the range of motion and access it functionally. If one does not, then extension movements may occur in the lumbar spine via some anterior pelvic tilt. However, one must not dismiss that upright posture needs sufficient quadriceps strength as well -- meaning, hip extension and knee extension get us to an upright posture and make locomotion possible. If we make the hip flexors or quadriceps tight, due to weakness of the lower abdominals or glutes,  we get anterior pelvic posturing and less hip extension (these are admittedly very rough principles, we all know it is far more complex that this).  What I am saying is that there is an interaction amongst groups of muscles, functional patterns of engagement, recruitment and whatnot. 

One must clearly realize how much knee and hip motions are coupled and work with and off of eachother.  If we bend over in a squatting type motion, we are in hip flexion and knee flexion. When we stand, hip and knee extension. These guys play off of eachother.  One must consider these issues when movements are more advanced and loading and loading rates are magnified, such as in squatting type lifting.  

A few weeks ago Bret Contreras in conjunction with Strength and Conditioning Research put out an article by Yamashita , yes, a 1988 article.  "EMG activities in mono- and bi-articular thigh muscles in combined hip and knee extension."  What this article looked at was what happened during isolated hip extension and isolated knee extension, and more importantly, what happened to the forces when both joints loaded simultaneously, paired in generating extension at the hip and knee, as in a squat. 

This article suggested that when hip and knee extension forces are generated in conjunction, the knee extensors are more activated than if the same force was generated in isolation. What this seemed to suggest is that during the extension phase of a squat, it is easy for the quad thigh muscles (rectus femoris, vastus medialis in this study) to to try and rule the movement, from an activation perspective -- the hip extensors (g. max and semimembranosus) take second seat.  We have talked many times about the dangers of this principle when we frequently say "the glutes should be in charge of the hip, not the quads, when the quads try to apply dominant control of the hip motion, trouble may ensue." Admittedly, this may not be entirely true and it is very loosely stated, but the principle has some sound value when it is approached from how we intend it to be heard, that many athletes do not have sufficient glute strength, hip extension range of motion, and poor control of pelvic neutral. So, they dump into the quads because as we see here in this study, they are very appropriately positioned to help synergistically drive the positioning for, and activity of, hip extension motor pattern production. Is this why we see small buttocks and large quadriceps in distance runners, and the opposite in sprinters ?  We think so, but we need to dive deeper into the research to prove or disprove it, but the principles seem to make sense.
This is why I like to initially drive my glute and hip extension work with my clients in a more knee flexed position, such as supine bridges.  I cannot say it better than Bret Contreras did when he reviewed this article,  

"So exercises that involve less knee extension (glute bridges, hip thrusts, deadlifts, pull throughs and back extensions) will tend to produce much greater hip muscle activation than those that involve more knee extension (squats, lunges, and leg presses), although there are always other factors involved of course!".  

If you are not following Bret's and Strength & Conditioning Research's work, you are missing out, They are thorough and insightful, they do their homework, learn from them.
We clearly need to dive into some newer research on this topic, we will see if we can squeeze out the time. 


- Dr. Shawn Allen, the other "gait guy"


Here is an embedded code for the beautiful slide that accompanied Strength and Conditioning Research's summary of the study. If you cannot find it above in this post, goto their Facebook page and scroll to Sept 22nd, 2016. You will find it beautifully laid out there.  Beautiful job S&CR!


<iframe src="https://www.facebook.com/plugins/post.php?href=https%3A%2F%2Fwww.facebook.com%2FStrengthandConditioningResearch%2Fposts%2F982124818565207%3A0&width=500" width="500" height="731" style="border:none;overflow:hidden" scrolling="no" frameborder="0" allowTransparency="true"></iframe>

Yamashita  1988. Eur J Appl Physiol Occup Physiol. 1988;58(3):274-7. EMG activities in mono- and bi-articular thigh muscles in combined hip and knee extension.
https://www.ncbi.nlm.nih.gov/pubmed/3220066
 

Knee hyperextension and delayed heel rise in an interesting sport, Racewalking.   If you have been in practice long enough, you should know by now that in order to truly help an athlete you have to know their sport, the subtleties and the specifics.  You have heard us talk about premature heel rise off an on for years. Today, you must consider the opposite, delayed heel rise and the bizarre loading responses that come into the kinetic chains from such a behavior.  Racewalking is a long-distance event requiring one foot to be in contact with the ground at all times. Stride length is thus reduced and so to achieve competitive speeds racewalkers must attain cadence rates comparable to those achieved by Olympic 800-meter runners for hours at a time. Most people cannot truly appreciate how fast these folks are going.  There are really only two rules that govern racewalking:  1-The first rules states that the athlete’s trailing foot’s toe cannot leave the ground until the heel of the leading foot has created contact.   2-The second rule specifies that the supporting leg must straighten, essentially meaning knee extension (and for some, terminal extension, ie. negative 5-10 degrees !) from the point of contact with the ground and remain straightened until the body passes directly over it. Again, essentially meaning full range knee extension for the entire stance phase of gait (early, mid and late midstance phases).    Delated heel rise ?   Clearly some folks are going to take knee extension a little more literally. Look at the fella in the red and yellow. Can you say knee HYPER extension ? This is right knee anteriormeniscofemoral impingement looming on the horizon, this is an anterior compression overload phenomenon via the quadriceps. This is often met in this sport with the  delayed heel rise  that the sport seems to often drive. Prolonging the foot ground contact phase, attempting to abide by Rule#2, “the support  leg must straighten”, can lead to knee hyperextension if one is not careful. This will put a longer stretch load into the achilles and posterior compartment mechanism and this prolonged stretch-contract load can eventually lead to local pathology let alone in combination with the anterior knee compression we just eluded to. These folks will also be at risk for more anterior pelvic tilt, distraction of the anterior hip capsule-labral interval, unique hip extension and gluteal integration, and even possibly altered hip extension motor patterning driving abnormal loads into the hamstrings and low back.  Just imagine the changes in the hip flexor strategies in this scenario.   To help your athletes, know their sport, know your normal biomechanics and know the pathologies when the rules of clean biomechanics are broken.  Today, on Rewind Friday, we will repost a more in-depth, with video, piece we did a few years ago on  Race Walking . You may learn more about normal and abnormal gait than you think, today we translate some of the rules of the sport of race walking into deeper thoughts on gait mechanics.  Here is the link to our more in-depth video assessment and dialogue on the fascinating sport of race walking. If you have never truly looked at this sport before, you should enjoy this  Rewind Post. (link).   - Dr. Shawn Allen

Knee hyperextension and delayed heel rise in an interesting sport, Racewalking.

If you have been in practice long enough, you should know by now that in order to truly help an athlete you have to know their sport, the subtleties and the specifics.  You have heard us talk about premature heel rise off an on for years. Today, you must consider the opposite, delayed heel rise and the bizarre loading responses that come into the kinetic chains from such a behavior.

Racewalking is a long-distance event requiring one foot to be in contact with the ground at all times. Stride length is thus reduced and so to achieve competitive speeds racewalkers must attain cadence rates comparable to those achieved by Olympic 800-meter runners for hours at a time. Most people cannot truly appreciate how fast these folks are going.

There are really only two rules that govern racewalking:

1-The first rules states that the athlete’s trailing foot’s toe cannot leave the ground until the heel of the leading foot has created contact. 

2-The second rule specifies that the supporting leg must straighten, essentially meaning knee extension (and for some, terminal extension, ie. negative 5-10 degrees !) from the point of contact with the ground and remain straightened until the body passes directly over it. Again, essentially meaning full range knee extension for the entire stance phase of gait (early, mid and late midstance phases). 

Delated heel rise ?

Clearly some folks are going to take knee extension a little more literally. Look at the fella in the red and yellow. Can you say knee HYPER extension ? This is right knee anteriormeniscofemoral impingement looming on the horizon, this is an anterior compression overload phenomenon via the quadriceps. This is often met in this sport with the delayed heel rise that the sport seems to often drive. Prolonging the foot ground contact phase, attempting to abide by Rule#2, “the support  leg must straighten”, can lead to knee hyperextension if one is not careful. This will put a longer stretch load into the achilles and posterior compartment mechanism and this prolonged stretch-contract load can eventually lead to local pathology let alone in combination with the anterior knee compression we just eluded to. These folks will also be at risk for more anterior pelvic tilt, distraction of the anterior hip capsule-labral interval, unique hip extension and gluteal integration, and even possibly altered hip extension motor patterning driving abnormal loads into the hamstrings and low back.  Just imagine the changes in the hip flexor strategies in this scenario. 

To help your athletes, know their sport, know your normal biomechanics and know the pathologies when the rules of clean biomechanics are broken.

Today, on Rewind Friday, we will repost a more in-depth, with video, piece we did a few years ago on Race Walking. You may learn more about normal and abnormal gait than you think, today we translate some of the rules of the sport of race walking into deeper thoughts on gait mechanics.

Here is the link to our more in-depth video assessment and dialogue on the fascinating sport of race walking. If you have never truly looked at this sport before, you should enjoy this Rewind Post. (link).

- Dr. Shawn Allen

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ETT and Hip Extension

Not Extra Terrestrial Tricks, but rather External Tibial Torsion. How it effects hip extension.

We received this question from Matthew P on our Facebook post from 8/1 (original post from here) which was based on this article, and thought it would make an excellent opportunity to teach. 

I looked at this yesterday and had actually first come across it a year or more ago when I was trying to find some resources for femoral torsion. You guys are about the only ones discussing at length the impact and implication of adult femoral torsion.

Re: tibial torsion and your post yesterday saying that > 30deg external torsion can affect both knee and hip extension, what I still don’t understand is the mechanism behind the hip limitation. How would that torsion translate through the leg to the hip?

There are a few things we need to remember to make sense of this:

  • tibial torsion is the angular difference between the tibial plateau and distal tibial malleoli and refers only to the tibia, not the entire lower extremity (see top photo)
  • pronation can occur in the rear foot, mid foot, and fore foot
  • pronation causes internal spin of the leg and thigh, due to plantar flexion, eversion and abduction of the talus (see middle photo)
  • internal spin of the hip causes posterior translation of the femoral head via the “glide and roll” phenomenon
  • these are appropriate mechanics during the 1st ½ of the gait cycle (initial contact to mid stance)
  • pronation is one of the 4 shock absorbing mechanisms (pronation, ankle dorsiflexion, knee flexion, hip flexion) of the lower extremity

now try this (yes, at home!)

  • flex your knee
  • internally rotate you leg
  • allow your arch to flatten
  • try and extend your hip

Remember these facts about supination

  • supination is initiated by the swing phase leg as it starts in early swing and continues to terminal swing (see third picture)
  • supination (from full pronation), should occur from midstance to pre swing
  • supination makes the foot into a “rigid lever” to transpose forces from above the foot into the foot and allow for propulsion (see third picture)
  • supination involves external rotation of the lower leg and thigh (see pictures 3 and 4)
  • external rotation of the hip is accompanied by anterior glide of the femoral head via the “glide and roll” phenomenon
  • this position puts the gluteal muscles (max and posterior fibers of the gluteus medius) at a mechanical advantage

now try this:

  • extend your knee
  • externally rotate your leg
  • you should have a full arch at this point
  • try and extend your hip

What did you (hopefully) learn?

  1. When the hip is in an externally rotated position it is easier to extend; the femur head moves anteriorly, the femoral joint capsule becomes tighter and stability is created
  2. when the hip is internally rotated, it is more difficult to extend
  • the femur head glides posteriorly, changing the axis of rotation of the joint
  • the gluteus maximus and posterior fibers of the gluteus medius are at a mechanical disadvantage

OK. Got it? We sure hope so! Excellent question, Matthew. Thanks for the opportunity to teach this concept.

The Gait Guys. Taking you closer to mastering the gait cycle with each post. 

Too much potential gait pathology all in one sport ? Racewalking … . 
Do not underestimate this title, you may learn more about normal running form from today’s blog post than you think.
 
For the best clips start watching at the 4:15 mark. 
The sport of race walking is an interesting one to say the least.  We had the pleasure for years of treating and working closely with one of our countries best race walkers and she taught me so much, not only about the sport but about the strange mechanics of the sport and the functional pathologies the sport drives from its unique requirements driving abnormal gait mechanics on each step.
Racewalking is a long-distance event requiring one foot to be in contact with the ground at all times (and a couple of other unique and wacky rules that we will discuss in a moment). Stride length is thus reduced and so to achieve competitive speeds racewalkers must attain cadence rates comparable to those achieved by Olympic 800-meter runners for hours at a time. Most people cannot truly appreciate how fast these folks are going, most folks will have to move into at the very least a gentle run to keep up with these folks.
 

There are really only two rules that govern racewalking:

1-The first rules states that the athlete’s trailing foot’s toe cannot leave the ground until the heel of the leading foot has created contact. The rule violation is known as "loss of contact". 

2-The second rule specifies that the supporting leg must straighten, essentially meaning knee extension (and for some, terminal extension, ie. negative 5-10 degrees !) from the point of contact with the ground and remain straightened until the body passes directly over it. Again, essentially meaning full range knee extension for the entire stance phase of gait (early, mid and late midstance phases). For those who do not study the details of gait, this may not seem like a huge issue, but it is because full lockout really never occurs in either walking or running.  And there is nothing like impacting a joint in full extension lock and heavy heel strike to take away all of the natural shock absorbing mechanisms of the lower limb. (watch the video at the 4:30 mark, Dang ! the dude in the red looks like his knees are going to fold backward there is so my knee extension !) There is some great slow motion technique breakdown at the 6:28 minute mark of the video. 

In getting around these 2 major rules:

- the hips must rotate a tremendous amount, with full pelvis rotation, to prevent the frontal plane pelvis motion which would be a loss of sagittal power. This produces the visually painful waddle that is classic to the sport.

- the arms are used aggressively to generate power and to help the lower limbs move through the cycle because of the unnaturally apropulsive nature of the overall technique. The arms also often move excessively into the frontal plane since they mirror the lower limb

- excessive lateral heel strike quite often ensues help keep the knee extended and in an attempt to keep the foot on the ground longer, to avoid getting red carded. 

- there is plenty of cross over gait and severe lack of ankle dorsiflexion for everyone to observe, both of these components combined with the above characteristics give the “Close to the ground” appearance that is attempted by all racewalkers.

- want to see some seriously gut wrenching biomechanics, forward the video to the 7:55 mark. Tell us that won’t cause problems down the road !

Breaking the Rules:

The rules are entirely subjective and enforced by real-time human eye (not video) judges along the course (3 red card violations render an event disqualification). Interestingly, and we have seen this first hand, athletes quite regularly lose contact (meaning initiating a float phase, which is what dictates the difference between running and racewalking) for a few milliseconds per stride.  This float can be detected on film/video which can be caught on film, but such a short flight phase is said to be undetectable to the human eye. Disqualifications (losing contact or bent knee) are routine at the elite level as evidenced by the famous 2000 Summer Olympic case of Jane Saville who was disqualified on her way to a gold medal.

Racewalking … .  a highly technical sport, more so than running.  If you ever get a chance to see someone do this sport first hand, it is truly engaging to a gait geek. Lots of eye candy, gait geek eye candy that is !

Shawn and Ivo… … the gait guys. 

The Consequences of Overstriding.

Consequences of Over Striding: “Call me Ishmael”.

Have you ever wondered what would happen if you were running and impacted the foot at foot strike at the end range ankle rocker (full dorsiflexion) with the knee extended ? Can you even imagine this ?  It is hard isn’t it.  (Be patient, we are about to show you, but for now just try to imagine it.)
Where would the shock absorption go ?
How could  you progress over the limb other than through hip rotation?  Because there certainly would be no pivot over the ankle joint, like a client with a fused ankle joint. The ankle and lower leg would be like a wooden peg leg, “Call me Ishmael ! ”.


And if the forces were moving up from the ground through the locked ankle mortise (which is again,terminal dorsiflexion) and a locked knee (again, in full extension) the forces through the hip would follow from the ground upwards. Creating a vaulting phenomenon. “Call me Ishmael”.
Can you picture this ?
If not, here is the video piece (VIDEO LINK) today very nicely depicting this awful biomechanical event.
You see, if you know your biomechanics, this stuff can virtually be created in your brain……. but it is always nice to see an athlete try it out.  That is why they get the big bucks !  Did you watch the video link yet ? He sure put the ACL and PCL in the octagon on that one !

Shawn and Ivo, the Biomechanics nerds……. as strange as Ishmael in the Octagon.

http://sports.yahoo.com/blogs/mlb-big-league-stew/houston-marwin-gonzalez-turns-most-spectacular-injury-season-144210692–mlb.html