The Gait Guys. Two weeks ago you talked about a dog’s gait, now cockroaches ? Yup, watching nature at work fosters much insight into gait principles.

Biomimetics, also known as Bionics, is another name for engineering systems that copy principles found in nature.

If you are real gait geeks you have probably seen some of the cool robots inspired after  the insect world. Many of these robots are called hexapods (six legged robots), just like insects. With 6 legs alternating limbs on opposite sides of their exoskeleton (see diagram above) it can provide an inherently stable tripod mechanism that is effective and efficient in when it comes to locomotion. Insects are great models because they have an extremely stable and efficient model of locomotion through something called a tripod gait. We have a video link demonstrating this a little further down.  At any time, cockroaches for example have 3 limbs in contact with a surface.   This tripod structure makes them very stable and mobile.

The stability of the hexapod comes from its ability to establish this gait pattern in which at least three legs are on the ground at any time. Just like the 3 legs of a tripod, when they are firmly planted, the platform is very stable.  You will notice from our year of blogging that we continue to talk about the foot tripod, consisting of stability points at the head of the 1st and 5th metatarsals and the heel. These 3 points of stability of the foot are necessary to make up the longitudinal and transverse arches of the foot. Without the ability to anchor these 3 points effectively on the ground the foot becomes unstable and compromised. Hence why we see bunions, hallux valgus, metatarsalgia, abnormal plantar callus patterns as well as various presentations of foot pain in feet that have lost the tripod ability. The key however is then to place, and maintain, the body mass within the confines or borders of the triangle made by joining these 3 tripod points (see the colored area in the diagram above). In humans, if your body mass deviates towards the outside of the tripod, in other words approaching or violating an imaginary line drawn from your 5th metatarsal to the heel (ie. approaching supination), you tip the foot laterally and begin to compromise the anchoring of the medial foot tripod (under the 1st metatarsal) and risk formation of bunions and hallux valgus among other functional pathologies of excessive or constant supination. On the other hand, If your body mass approaches or exceeds the arbitrary medial border of the triangle delineated by a line drawn from the head of the metatarsal to the heel  you are considered a possible hyperpronator and all of the functional pathologies that accompany it (ie. plantar fasciitis etc).  Bottom line … a tripod is stable, just stay withing the colored lines. Note in this cool video (click here) how clear the 3 pronged tripod engages and how the body mass of the robot stays within the borders of the tripod limbs. In other words, keep your ankle and more specifically the force vector, over your foot tripod (the colored lines),  and most pathology issues will be absent. The closer you get to tipping the tripod, the closer  you are getting to developing biomechanical pathology in the lower limb.  Put another way, by increasing weaknesses in the foot intrinsic and extrinsic muscles and possibly the other stabilizers of the lower limb and pelvis, the closer your body mass will fall towards the edges/limits of the tripod triangle borders. And the closer you are to the risk of gait pathology and pain.

( In the diagram above, for you hexapod insect loving gait fans, the most basic hexapod walking pattern is called the alternating tripod gait. Taken from this site, in this gait, the six legs are treated in two groups of three. Either group of three is a tripod formed by the front and rear legs of one side, and the middle leg of the opposite side. The three component legs of each tripod are moved as a unit. As one tripod is lifted, the other tripod pushes forward. In this gait it can be helpful to think of each tripod as a foot and compare it to your own bipedal walking where as one foot is lifted the other foot pushes forward.)

And you still thought we were just your average Gait Guys, didn’t you ?! If it walks, trots, gallops, canters, jumps, runs, jogs or whatever….. we are on top of it.  Yes, even if that means cockroaches ! We are here to stay gang, in 2012 we will begin to execute our plan for intergalactic dominance, gait related only of course.

Nerd Shawn & Geek Ivo

A Coach with Anterior knee pain:  About as common a problem as finding dirt on a child.

We get emails like this all the time. Here is one from a coach with a problem.

Hi Gait Guys,

I was just found your blog visiting one of the running sites I like coachjayjohnson.com. I’m a high school xc/track coach and a former runner myself. I say former because I dug a nice hole in my cartilage in the lateral trochlear groove about 4 years ago from running. This actually happened 3 months after I stopped wearing the custom orthotics i had been wearing for about 8 years. What a mistake that was, but the biggest mistake might have been getting them in the first place.

Anyways, 3 months ago I had a procedure done to regrow the cartilage. this was done at the stone clinic in San Francisco. The doctor said I should wait a year before I attempt to run again. I’m fine with that but sometime next year once my knee is feeling good enough I’d like to come see you guys before I start running again so that you can help analyze everything and get me out there running again with good form and in the correct shoes etc. Where are you guys located? Also, are you going to come out with some new DVDs?

Thanks,
(name removed)

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What The Gait Guys have to say …

Dear Coach:

(Links in our discussion have been embedded for you and other readers and we have included a picture above so everyone else will know where your problem was.)

Anterior knee pain in runners is about as common a problem as finding dirt on a child. You have described the all to common, osteochondral defect. IT is a defect of bone and cartilage quite often from blunt or repetitive trauma.

Knee joint anterior malalignment is multivariably associated with patellofemoral osteoarthritis (study). Alignment issues at the knee can be driven by variations of the optimal anatomy (versions and torsions, see a post on this from ~3 weeks ago) but in our opinion they are often driven from other factors most notably improper biomechanics driven by muscle weaknesses-tighness. However, other factors can come into play to complicate the scenario, such as poorly selected footwear for a foot type. Alignment at the knee is subservient to the mechanics at the hip and foot. Both the hip and foot are multiaxial  joints, whereas the knee in its healthy state and most basic description, a sagittal hinge joint (sure, miniscule rotation). When the hip or foot are prostituted and some of the availability of their normal motion is lost or changed (as is possibly the case of an orthotic as you eluded to, however in the hands of a skilled practictioner the orthotic can help positively restore compromised function, if they understand and assess whole limb kinetic function) the knee joint can often find itself in the middle of altered biomechanical force streams. This all to often can lead to anterior knee pain, compromised function of the patellofemoral joint.  This, as in your suspected case, can lead to abnormal cartilage wear at the interface of the two bones.

In one article it was proposed that physical activity may modify the association between joint incongruity and cartilage loss, and can be further affected by subject characteristics such as gender. It must be part of the thought process that rather than it being the activity, is more likely to suspect altered biomechanics during said activity as being the culprit.  Understanding these complex interactions will help optimize strategies to maintain patellofemoral joint health. However, this study found that for every one-degree increase in the proximal trochlear groove angle at baseline, there was an associated 1.12 mm  increase in the annual rate of patella cartilage volume loss. This brings a person’s given anatomy, perhaps suboptimal anatomy, into play and thus adds one’s risk factors. There was a trend for this effect to occur for males, as well as people participating in vigorous physical activity. Males who exercised vigorously were more adversely affected.

In conclusion, this study showed that in vivo engineered cartilage was remodeled when implanted; however, its extent to maturity varied with cultivation period. The results showed that the more matured the engineered cartilage was, the better repaired the osteochondral defect was, highlighting the importance of the in vitro cultivation period.

There are many surgical interventions out there for anterior knee pain, such as tuberosity transfers, retinacular releases, injections, and God forbid patellectomies among others (yes, we have clients who decades ago had this done, imagine that! Thankfully this radical move is no longer done !). Most people simply need a well versed biomechanist who understands the whole kinetic chain, understands the force streams, can assess for the limitations and reduce them to restore the previous normal mechanics.  Sadly, sometimes interventions are not optimal or precise and folks end up like you coach. And then surgery is your only option.  Thanks for sharing your story and reaching out to us. Sharing your anonymous story may help others avoid your painful journey. We would be happy to see you, we are getting more and more letters like yours both here in the home land and internationally. Hopefully, our mission will help reduce these problems, if at least just a little. (PS: yes, our 3 part Shoe Fit / Biomechanics & Functional Anatomy DVD and online program should launch in February. Information about the launch will be right about the time phase 2 of the website will lauch www.thegaitguys.com).

Best to you.

Shawn and Ivo, The Gait Guys

Genu valgum in kids: What you need to know

We have all seen this. The kid with the awful “knock knees”.  It is a Latin word “which means “bent” or “knock kneed”. It appears to have 1^st been used in 1884.

This condition, where the Q angle angle exceeds 15 degrees, usually presents maximally at age 3 and should resolve by age 9. It is usually physiologic in development due to obliquity of the femur, when the medial condyle is lower than the lateral. Normal development and weight bearing lead to an overgrowth of the medial condyle of the femur. This, combined with varying development of the medial and lateral epiphysies of the tibial plateau leads to the valgus development. Gradually, with increased weight bearing, the lateral femoral condyle (and thus the tibial epiphysis) bear more weight and this appears to slow, and eventually reverse the valgum.

Normal knee angulation usually progresses from 10-15 degrees varus at birth to a maximal valgus angle of 10-15 degrees  at 3-3.5 years (see picture).  The valgus usually decreases to an adult angle of 5-7 degrees.  Remember that in women, the Q angle should be less than 22 degrees with the knee in extension and in men, less than 18 degrees. It is measured by measuring the angle between the line drawn from the ASIS to the center of the patella and one from the center of the patella through the tibial tuberosty, while the leg is extended.

Further evaluation of a child is probably indicated if:

• The angle is greater than 2 standard devaitions for their age (see chart) 
• If their height is > 25^th percentile 
• If it is increasing in severity 
• If it is developing asymmetrically

Management is by serial measurement of the intermalleolar distance (the distance between ankles when the child’s knee are placed together) to document gradual spontaneous resolution (hopefully). If physiologic genu valgum persists beyond 7-8 years of age, an orthopaedic referral would be indicated but certainly intervention with attempts at corrective exercises and gait therapy should be employed. Persistence in the adult can cause a myriad of gait, foot, patello femoral and hip disorders, and that is the topic on another post.

Promotion of good foot biomechanics through the use of minimally supportive shoes, encouraging walking on sand (time to take that trip to the beach!), walking on uneven surfaces (like rocks, dirt and gravel), gentle massage (to promote muscle facilitation for those muscles which test weak (origin/insertion work) and circulation), gait therapeutic exercises and acupuncture when indicated, can all be helpful.

Ivo and Shawn…  The Gait Guys…Promoting foot and gait literacy for everyone.

We are not generally fans of Nike, but they do have some cool commercials. Here is one of our favs of cyborg parkour.

Have a great Friday

Ivo & Shawn

Gait ischemia? Blood flow affecting performance.→

Research evidence that gait is altered in ischemia (inadequate blood supply) environments.

Know someone with diabetes, peripheral artery disease or spinal stenosis (especially the vascular variety) ?

This study’s findings indicate increased “noise” and irregularity of gait variability patterns post-ischemia. In young healthy individuals who do not have neuromuscular impairments, significant gait alterations are present during walking after a period of interruption of blood flow. This could be from something as simple as muscular compression, or something more serious.     

We just wanted to wet  your appetite for some stuff like this coming your way, from us, The Gait Guys.  If this does not make you think about compressive socks and stockings, you need a second cup of coffee this morning !

Shawn and Ivo

                                                                                                                                                                                             

Gait variability patterns are altered in healthy young individuals during the acute reperfusion phase of ischemia-reperfusion.

J Surg Res. 2010 Nov;164(1):6-12. Epub 2010 May 18. Myers SA, Stergiou N, Pipinos II, Johanning JM.

Source

Nebraska Biomechanics Core Facility, University of Nebraska at Omaha, Omaha, Nebraska 68198-3280, USA.

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Gait: Does Minimizing center of mass vertical movement change your metabolic cost ?→

Research article: Minimizing center of mass vertical movement increases metabolic cost in walking.

Ortega JD, Farley CT. Locomotion Laboratory, Dept. of Integrative Physiology, University of Colorado, Boulder, CO 80309-0354, USA. ortegajd@colorado.edu

J Appl Physiol. 2005 Dec;99(6):2099-107. Epub 2005 Jul 28.

So what is this article’s bottom line ? The premise of the research article was to look at the relationship between vertical movement in gait and its metabolic cost by having human subjects walk normally and with minimal center of mass vertical movement (“flat-trajectory walking”). What the article found was that it costs more to move with a flat trajectory. In other words, dampening the normal vertical oscillations is not a good thing.  But we have some concerns.

Not that we have a major problem with this study, but we do have two concerns we think should have been brought up problem.

1- Were these folks in the study assessed for biomechanical compensations ? You have read our discussions on impaired ankle rocker. And one of the major flaws of impaired ankle rocker is the premature heel rise gait, where the person can adopt a rather boucey vertical gait, almost appearing to walk on the ball of their foot. These folks have a very vertical gait.

2- Since the study concluded that the less vertical trajectory gait was seen to be far less metabolically efficient it is a well founded question to ask more about the strategy they employed. In the study they merely added more joint flexion to dampen the vertical trajectory.  But, had they been coached to use the core to minimize vertical trajectory and utilize the energy moving forward while still obtaining some of the normal biomechanical components, some of which take advantage of limb extension, would the study have found the same thing ?  Once again we find a good study but one that bodes more questions than it answers, such as, did the researchers really know enough about gait biomechanics to give good cues?  Furthermore, how much vertical is too much ? How much dampening is too much ?

  We still appreciate the study and its findings, but you cannot trust everything you read, at least not without reading the fine print.  Here is the full abstract below. Read it yourself and if you are curious enough, get the full study for yourself.

Shawn and Ivo…….keeping you on the edge of the research.

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Journal Abstract

A human walker vaults up and over each stance limb like an inverted pendulum. This similarity suggests that the vertical motion of a walker’s center of mass reduces metabolic cost by providing a mechanism for pendulum-like mechanical energy exchange. Alternatively, some researchers have hypothesized that minimizing vertical movements of the center of mass during walking minimizes the metabolic cost, and this view remains prevalent in clinical gait analysis. We examined the relationship between vertical movement and metabolic cost by having human subjects walk normally and with minimal center of mass vertical movement (“flat-trajectory walking”). In flat-trajectory walking, subjects reduced center of mass vertical displacement by an average of 69% (P = 0.0001) but consumed approximately twice as much metabolic energy over a range of speeds (0.7-1.8 m/s) (P = 0.0001). In flat-trajectory walking, passive pendulum-like mechanical energy exchange provided only a small portion of the energy required to accelerate the center of mass because gravitational potential energy fluctuated minimally. Thus, despite the smaller vertical movements in flat-trajectory walking, the net external mechanical work needed to move the center of mass was similar in both types of walking (P = 0.73). Subjects walked with more flexed stance limbs in flat-trajectory walking (P < 0.001), and the resultant increase in stance limb force generation likely helped cause the doubling in metabolic cost compared with normal walking. Regardless of the cause, these findings clearly demonstrate that human walkers consume substantially more metabolic energy when they minimize vertical motion.

You have heard us talk about weakness (short weak and tight weak) muscles all the time on Youtube: The Gait Guys; now here is the neurology behind it. Think about this concept the next time you see a gait compensation and think of the muscles (agonists/antagonists) involved.

On and on goes the barefoot debate. 

There is no single right answer, so use your head.

article link, click here

We have been saying what this article talks about all along, even years before the Vibram 5’s hit the market, back when Vibram came to us to ask us for our thoughts on the early versions.  You will see our soapbox rant on this topic over and over again in our blog posts and it is the modus operandi behind our new 2012 Shoe Fit program that will likely launch February 1st in several forms for several professions to meet everyone’s needs.

That modus operandi being that not everyone has a foot type, anatomy or biomechanics to get into minimalist shoes, without a possible cost that is.

In this nicely written article by Cynthia Billhartz Gregorian “Barefoot running: Sales grow, but so does debate about benefits, safety” at the link above she lightly covers some of the aspects of the debate.  We have read just about every piece that has come out on the barefoot-minimalist trend. Sadly, some of the blogs are mere opinion and it is rare that the honest truth comes out.  That truth being our mention above that some folks just do not have the skill, endurance, strength or anatomy to delve into footwear that does not support or protect their physical limitations.  Lets be honest, at 5'9’’ I have to come to the realization that no matter how much i practice to be in the NBA I am not going to make it. I just do not have the physical anatomy to be an NBA star.  And some people, no matter how much they want to run barefoot or minimalist, just do not have the anatomy to allow it. Someone with a history of foot pain who has a rigid forefoot varus really is not going to do well in minimalist shoes. There are articles written out there that just tell people to bite the bullet and go 100% into their new minimalist shoes, into the natural way they were supposed to run from the very start and force the body to adapt, that the new form they adopt will take care of any problems. Well, in our experienced and educated opinion, that is just not smart. Someone who has a shortened posterior compartment (calf-achilles) after being in heel shoes for years is going to have several flaws biomechanically going to minimalist shoes right off the bat. One example, just one for now, is that the person is going to have premature heel rise and thus premature forefoot loading response around a compromised ankle rocker mechanism. And there are many others of course.

Here is the bottom line as we see it. No shoe company is going to run a commercial or add on their product with the warnings on the cover or in the fine print. We are not talking about cigarettes here.  Admitting that some people should not be in their product would be admitting that the product has limitations and risks.  What kind of advertising add would that be ? Besides, admitting to limitations or mentioning warnings is a mere step away from liability cases.  We are pretty sure of this, after all, look what happened to the Shape Up Shoe in the courts.

Here is what we say to the naysayers, look at the research and use logic.  If you are new to the game, leave the extremist blog sites for those that are looking for radical opinions. Because we do not have any openings in our clinics for the next several weeks if you throw caution to the wind.

Good running to you all in 2012, use your head, for the sake of your feet.

Shawn and Ivo

Ataxic gait?

We hope you have begun the new year in a NON ATAXIC manner. Lets look at the origin of the word:

Ataxia: Greek, from a or without + tassein to put in order or “without order”. Ataxia is truly gait without order, and we will see why momentarily. The term was coined in 1670. Every September 25th is International Ataxia Awareness Day. Mark THAT ONE on your calendars!

Ataxia an inability to coordinate voluntary muscular movements that is symptomatic of some nervous system disorders and injuries and not due to muscle weakness.

It is a lack of afferent information either GETTING TO the CNS, BEING PROCESSED BY the CNS, or OUTPUT FROM the CNS. We can still hear Dr Carrick saying “where is the longitudinal level of the lesion? Is it at the receptor, the effector, the peripheral nerve, the spinal cord, the brain stem, the thalamus, the cerebellum or cerebrum?” This mantra, still rings true many years later, as it gives us the afferent pathway to the brain and higher centers of the CNS.

Ataxic gait, not to be considered synonymous with Fredreich’s Ataxia (the genetic disorder described in the 1860’s, related to spinal cord and cerebellar degeneration), can be due to any number of causes which affect processing of afferent information. One too many Tequila’s (100% agave of course), barbituates, joint pathomechanics, diseases affecting receptors (like syphilis or leprosy), diabetes and other forms of peripheral neuropathy, spinal cord injury or disease are only a few of the causes. Virtually anything that can affect the afferent processing or efferent arc of the processing of proprioceptive information.

The large amplitude corrective movements are clues to the CNS that something is awry and are a necessary component of the compensation. Here , you truly are seeing the result of the compensation.

The video offers a simplified explanation and nice clinical example of an ataxic gait. If you don’t believe it, try some field research (or perhaps you already have) with the ethanol of your choice and see for yourself. Of course, some of THAT ataxia comes from changes in specific gravity of the endolymph in your inner year, but that is the subject of another post.

Ivo and Shawn. The Gait Guys…New and Improved for 2012