Interpretation of GAITRite mat data

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Hello,

Does anyone here use the GAITRite mat regularly and know how to interpret the data generated?

I need some guidance so any help would be greatly appreciated.

 

Hi,

What data are you looking at?

 

Im looking at the centre of pressure values in particular. When i save to excel I get so much data generated that I dont know what it means.
Im currently doing a study using the GAITRite, with 3 different conditions for each subject and each condition has 6 trials. I am stuck at this point and need to know what to extract for my data analysis test.

 

Ok. Forget your subjects and cut back to COP values. Do you understand what they mean?

 

Hi David,

No, I don't know what the values mean. The data doesn't even show what the units of measurement are ie: Newtons

 

That's where you need to start then. I'm not familiar with this specific type of equipment, although I've used Tekscan and Musgrave vertical loading systems in the past.

If you are a student, see your lecturer. If you are a post-grad see your supervisor, otherwise give the equipment sales team a ring and explain your problem.

Once you know what you're looking at it should be a simple matter to extract whatever data you need.

Regards,

David

 

Thank you David. Unfortunately my supervisors and lecturers are all on annual leave. I did speak to a rep from the company that distributes gaitrite in the UK but he was more on the sales aspect. I have now emailed the company direct at its US headquarters, so fingers crossed they can help.

Thank you for your advice,

Kind Regards,

 

I don't have experience with this system but I found this manual who could be useful if you don't have it: http://www.ncope.org/assets/pdf/GAITRite.pdf?20151105 Starting from page 33 there are some indication regarding COP

On the other hand I think you should know what you want to measure independent of the system you are using and prior to start to use it !Having this in mind when you'll have a system you'll search more precisely what you want to achieve.
For example: what means COP values ? The coordinates of COP points related to the GAITRite reference system? This means you should search in the Excel file for some data which will include: time, X coordinates, y coordinates ! Try to export the data in the excel format and look at the header as it should have indication about the exported data.

Also, this paper could be useful: http://www.nyu.edu/classes/mcdonough/gr_art.pdf

Hope these helps,
Daniel

 

I had this problem when I gained access to an EMED in aproximately 1992. I would suggest my paper

Center of pressure and its theoretical relationship to foot pathology.
Fuller EA.
J Am Podiatr Med Assoc. 1999 Jun;89(6):278-91.

Another paper to read is the old classic Hicks article from 1954 on the function of the muscles. Hicks took cadaver feet and then pulled on the muscles to see where the balance point would shift. Hicks' balance point is the same thing as center of pressure. The important point to understand here, that is on area my paper did not go into, is that muscle contraction shifts the location of center of pressure during gait. Different muscle activation will shift the center of pressure to different locations. It is almost a measure of behavior rather than a pure mechanical measure.

As Daniel pointed out center of pressure data will usually be an x coordinate and a y coordinate to give a location (length measure ie cm) from a zero point that is defined as somewhere on the mat. So the data will be an x and a y coordinate over time. One problem with Mat center of pressure data is that the foot doesn't hit the same place on the mat every step. Any analysis of mat data will have figure out where the foot touched relative to zero point of the mat so that data from one step can be compared to another. A line connecting the first contact point and the last can be quite inconsistent when the last toe off changes from step to step. There is also an inherent problem in using some of the center of pressure data to determine the location of the foot when your experimental outcome is how the center of pressure location changes relative to the foot.

Some have looked at speed of movement of center of pressure change. I'm not aware of any papers that have looked at validity of this measure. Danenberg has discussed a delay in calcaneal unweighting as being pathologic and removal of this delay with an orthotic as being correlated with improved symptoms. It would be nice if someone could test this idea in a paper.

Eric

 

Thank you Daniel and Eric for your advice. As there is a vast amount of data generated for the centre of pressure and it is difficult to interpret as you have mentioned in your paper Eric, I am now looking at other parameters that the Gaitrite records to look at changes in loading patterns.

Out of interest, what would Podiatrists on this forum choose to look at from the following parameters?


step time
cycle time
step length
stride length
single support and double support in % of the gait cycle
toe in/out in degrees
ambulation time
velocity
cadence

 

velocity and trajectory of the COP

Daniel