What do we mean by 'motion control' in running shoes

Getting a little sidetrack from here, is there any need to have more than one pair of shoes for running activity? If so ,why?

 

Hi all,

Simon B wrote:
It not only was able to demonstrate a significant shift of the COP laterally in a pronated population.. but most interestingly and excitingly.. we achieved a refractory effect without the stimulation for about 1/2 hour after the test.. more to come..

There is more than one way to shift the center of pressure laterally. Yes, CoP = center of pressure.
1. You can have a "pronated" foot in which you increase the activity of the posterior tibial muscle and this will shift the CoP laterally.
2. You can have a foot with a laterally deviated STJ axis, that in static stance, to keep the moment from the pronation side of the axis equal to the moment from the supination of the axis, will have to have very high pressures laterally. This will pull the center of pressure lateral because the cop is an average. Also, in these feet as the heel lifts in gait. the Achilles tendon will apply a supinator moment that will tend to shift the CoP more lateral.
3. A "pronated" foot that has the classical uncompensated/ partly compensated varus. In this foot, there is lack of range of motion, of all of the joints of the foot, to significantly load the medial colum and hence high lateral pressures.

So, to explain the study, if you could get high medial pressures before intervention and then high lateral pressures after intervention, one explanation is that there is increased posterior tibial activity.

Regards,

Eric Fuller

I was just going to put a flying pig as my avatar and then this igs: I'm still looking

 

Hi,

The shift of the COP to lateral or medial in pronated feet depends on the foot type in relation to the motion occured in the midtarsal or subtalar joint. There are curved medial foot types (with just pressure on the forefoot and heel) who pronated in the subtalar joint (even midtarsal) excessive (analysed by video) and they COP will go medial and others who or very flat (midtarsal pronation, with pressure even in the medial part of the foot) who have a lateral COP line (depends on compensation, like fuller was mention). I think we can't use just only the COP line to analyse a patient to say how the foot will move dynamical. And looking at the research there is now clearance about the COP line.

Best regards,

Kerstin

 

Kerstin;
can you list the research you have to support what you've written?

Also, I'm not sure sure about the clearance of the COP line?

What did you mean by that?

Sincerely;
Bruce

 

Don't wish to clog up “Atlas” thread, but Toomoon, with over 28 years of making shoes (l also build lasts for individual clients), l disagree with this statement

“In fact this is a urban myth.. there is no such thing as straight or curved last footwear.”
If we are going to discus this maybe we should start a new thread out of respect for the current thread subject and poster ?

 

Hello Bruce,

I think we are all agree that the foot is not a rigid structure so lots of torsions and collapses can happen in the foot. This movements which occurs in the midfoot region will have an influence on the evolution of the COP line when going to the forefoot. This movement depends on the foot structure and motion mobility in the midfoot region, first ray and 1ste MTPJ. We can just say when we speak of looking to the COP in the forefoot region that there is a pressure to pronation but this means not that there is a pronation movement. Bart Van Gheluwe has done a research on the COP and subtalar motion and he found a poor correlation of a medial deviated COP and pronation (this is not yet published). The same little correlation has been found in a research by sharon Dixon.
But, Friso Hagman who has done his PHD on the COP under the calcaneus has found a correlation between subtalar pronation and a more medial deviated COP line under the heel region (will be published).

Best regards,

Kerstin

 

Kerstin;
thanks for replying. If I understand you correctly, you are saying the Bart has found that there is rarely medial deviation of the CoP with foot pronation?

I'm fortunate to have a copy of Friso Hagman's book, thanks to Bart , and was interested in some of his findings in regard to the calcaneus.

I think some of the different findins regarding CoP have a lot to do with different systems used, ie Tekscan, Pedar and RS Scan. I'm only familiar w/ Tekscan obviously, but I am always amazed at some of the PEDAR results I've seen published as they just dont' often correlate with what I see with my Tekscan system.

Cheers!
Bruce

 

Kerstin, Bruce, Eric and Others:

CoP positioning can not be used as an absolute measure of either subtalar joint (STJ) rotational position or STJ spatial location. Of couse, it makes sense that as the STJ pronates in stance that the CoP would tend to shift medially and as the STJ supinates the CoP would tend to shift laterally. However, even if the person had a triple arthrodesis, and therefore had no STJ rotation, the CoP could shift medially during gait if the angle of gait is more abducted than normal and the CoP could shift laterally during gait if the angle of gait is adducted.

Furthermore, just looking at CoP progression and/or absolute CoP position does not tell you anything about the prevailing STJ moments unless the spatial location of the STJ axis and the direction of the GRF vector at that instant in gait is known. In other words, CoP is only one small part of the complete picture of knowing how that foot is functioning during gait and what abnormal forces/moments are that are the cause of the patient's pathology.

 

Miss Gangrene:

Actually, this is a very good question and I think is an important consideration for all sports-minded podiatrists to consider for their long-distance runner patients.

I recommend runners that are doing more than 40 miles per week to alternate between two different pairs of shoes (of slightly different midsole design) in order to not put the same stresses through their feet and lower extremities every time they run. When I was training 70-90 miles per week at the height of my marathon training career, I had three pairs of running shoes of different design that I rotated through in order to decrease my frequency of injury.

 

Hi, Boots n all

I would like to hear your point of view on this (especially because, quoting Roberto Benigni "I already used all of my English" on this)

 

l was not sure if there was an interest, l will post it "General" for you to look at and reply