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hi,

The podiatrist in me is used to providing orthoses for the treatment of injury's, but the athlete in me is also interested in performance.

this is totally selfish, but I thought it may evoke an interesting discussion in regard to the action of orthoses and again question our reasons for the differant perscriptions which we use!

I would class myself as an elite distance runner(no comments please). I have suffered with a varity of ailments over the years for which I use orthoses when running. these have done their job in terms of injury pervention, and I assumed they would aid performance due to improved biomechanical function(improved propulsion, enhanced windless, decresed fatigue etc). However, this is not the case! I always feel that when running (at speed) I have decresed propulsion and a percieved increase in effort for given returns. I was told that the weight of the insoles often balences out any funtional improvements but surely i shouldn't see a deteriation in performance?

biomechanically, i'm a heavy pronator. FHL and ankle equinous of course, forefoot varus/supinatus(whatever?). forefoot striker. orthoses used have intrinsic forefoot posting with small rearfoot post and skive, made from a very light carbon fibre.
yes, i know I'm just one case but like I said just thought would be an interesting discussion!

your comments

G

In several threads I have commented on our 'in press' work that showed no correlation between changes in rearfoot motion and symptom change with foot orthoses.

Following on from that we are looking for parameters that foot orthoses change that are related to symptom change ... while still preliminary, one parameter that does appear to be related is timing of heel unweighting - in the context of your message, the sooner the heel unweights, the faster you move forward ---> maybe better performance.

Another parameter we just getting excited about is the sinusidol motion of the bodies center of mass and the effect foot orthoses have on it. The center of mass should have a "perfect" sine wave motion to it and it could be assumed that the lower the height of the wave form, the more efficient gait is. The more efficient gait is --> should be able to run faster. We are measuring changes in that height and how much work is needed to raise the CoM and how foot orthoses change that.

The next challenge is to convert that into something practical ... (ie what is the relationship between manipulating those parameters with foot orthoses and symptom changes and performance enhancement).

We live in exciting times....

__________________
Craig Payne
Department of Podiatry
La Trobe University
Melbourne, Australia
http://www.latrobe.edu.au/podiatry
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Related thread:
Elite athletes and foot biomechanics

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Gareth:

I couldn't resist making a comment on that you consider yourself an "elite" distance runner. I previously was a good long distance runner with a personal best in the marathon of 2:28. However, I trained and raced with others that were considered elite...much faster than I.

But, to get to the story, when I was an undergraduate at UC Davis, I took a graduate level exercise physiology course from my former cross-country coach who was also a nationally recognized PhD researcher in exercise physiology. He would always be lecturing about average vs elite athletes in comparing research findings in exercise physiology. One day, I asked the question in class: how fast do you need to run in the marathon to be considered an elite distance runner? He said: Much, much faster than you can run the marathon in, Kevin!

Needless to say, the rest of the graduate students had a good laugh at my expense as the only undergraduate in the class. This was in 1979 and my professor went on to say that he considered an elite distance runner to have run a 2:15 marathon or better. Generally elite distance runners are considered to be nationally ranked or Olympic caliber athletes.

The bottom line with orthoses and running performance:

1. There is no research, to my knowledge, to either indicate that foot orthoses improve the performance of running or increase the metabolic efficiency of running. In fact, the added mass to the shoe may decrease performance and decrease the metabolic efficiency of running probably due to the increased moment of inertia of the leg during the swing phase (i.e. forward recovery phase) of running since the mass added to the leg, even though is relatively small, is a relatively large distance from the knee joint axis.

2. However, training in orthoses may allow higher and harder training mileages that will alow the athlete to run faster and farther due to decreased injury frequency. This effect may allow foot orthoses to make them run faster over time. I have experienced this effect first hand when I was actively competing in marathons and shorter distance races during my more youthful years. However, I have only anecdotal evidence to back this up.

In your case, you may want to add a little bit of forefoot varus extension to your orthosis to increase your propulsive efficiency (you don't want the orthosis to unload the medial metatarsal heads and digits too much or you lose propulsive efficiency by propelling more off the anterior aspect of the orthosis). The windlass does not work in running like it does in walking since the requirements for 1st mpj dorsiflexion are less in running than in walking.

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Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
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Sacramento, CA 95825 USA
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Did you mean valgus Kevin?

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Thank you for your replys! I said no comment in regard to the 'elite' comment. It dosen't really matter what the def of elite in running is, as it is only an opinion! Was ment as tongue in cheek!

The windlass does not work in running like it does in walking since the requirements for 1st mpj dorsiflexion are less in running than in walking.

Kevin please expand on this, I have come accross this before but never really got it!

regards

gareth 'elite' Klepacz

Is that correct? Is there a reference?

No, I meant forefoot varus. Runners, especially "elite" runners like Gareth, will tend to have significant running limb varus that, when combined with a pes planus deformity, will often result in a need to support the medial column more during running. However, I wouldn't generally also use this orthosis for walking since it may cause increased risk of 1st mpj problems such as hallux limitus.

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Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************

Thanks. Do you not think you get the "prolonged propulsion" effect of forefoot valgus wedging in running?

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I don't think you can make any generalizations in this regard. However, many more runners "need" forefoot varus wedging than do walkers to optimize function in their chosen gait activity. In my experience, forefoot valgus extensions on orthoses will tend to cause rapid early stance phase pronation in most runners and, therefore, pronation-related symptoms will tend to occur.

Forefoot varus extensions on orthoses will tend to many symptoms improve, especially those cause by excessive STJ pronation moments such as medial tibial stress syndrome, medial tibial stress fracture, posterior tibial tendinitis and patello-femoral syndrome where the goal of the orthosis is to decelerate early stance phase pronation and during the time of the running gait cycle where eccentric contractions are largely occurring in the lower extremity musculature and tendons.

Running and walking are very different in regard to what makes propulsion more efficient. I think that most podiatrists, even ones that understand walking biomechanics and walking orthoses very well, think that you can readily transpose efficient walking orthosis design directly to efficient running orthosis design....I don't think you always can.

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************

I believe this is correct from doing slow motion gait analysis on many students walking and running during my Biomechanics Fellowship and from seeing clinical evidence over the past 21 years that many patients with painful hallux limitus with walking can run with no pain. Sorry, no references that I know of. However, I am very certain of this one. Should be an easy enough of a study to do.

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************

The sinusoidal pattern of the rise and fall of the CoM during walking and running are exactly opposite of each other when comparing the two activities. At the middle of midstance during walking, the CoM is at its peak and in the middle of midstance during running, the CoM is at its trough. Just after midstance in running, when the heel lifts from the ground for propulsion, the CoM is rising toward its peak, while just after midstance in walking, when the heel lifts from the ground for propulsion, the CoM is falling toward its trough.

Therefore, when individuals run, they "jump off their hallux" in propulsion with their center of mass (CoM) rising upward while the hallux is being dorsiflexed by the ground. Therefore, during running, the plantar hallux will be unloaded very rapidly when pushing off the ground to the next stride which decreases the demands for hallux dorsiflexion.

However, when individuals walk, they "step forward over their hallux" in propulsion with their CoM falling downward while the hallux is being dorsiflexed by the ground. Therefore, during walking, the plantar hallux is loaded relatively slowly when pushing off the ground to the next stride which increases the demands for hallux dorsiflexion when compared to running.

And, by the way, all this talk of functional hallux limitus (FnHL) being important during running (or in running shoe design), I think is based on clinicians thinking that the biomechanics of the hallux during running is the same as in walking, which I'm sure it isn't. So don't be so sure that a individual that has FnHL during walking will have any problems with it during running, since the vertical movement pattern of the CoM during running and walking and, as a result, the biomechanics around the first metatarsophalangeal joint during propulsion, are so different.

__________________
Sincerely,

Kevin

**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College

e-mail: kevinakirby@comcast.net

Private Practice:
107 Scripps Drive, Suite 200
Sacramento, CA 95825 USA
My location

Voice: (916) 925-8111 Fax: (916) 925-8136
**************************************************