Normalizing gait center of pressure data

[Kathleen Thomas]

Hello all,

I have a large amount of gait COP data from a pressure plate installed within a treadmill and have a couple of questions regarding analyses.

1. Do you normalize the data as you would with standing posture COP data? If so, what is the best way to do that?

2. I have a spreadsheet of data with time, position, left leg force (N), right leg force (N), Butterfly force (N), Butterfly x (mm), and Butterfly y (mm). At the time, the COP (butterfly) data is not divided into R/L sides. I would like to seperate the COP x/y data within each leg. Does anyone have some suggestions as to how divide the data into seperate legs?

Thank you in advance for your assistance.

Sincerely,

Kathy Thomas

[Ann Hallemans]

Re: Normalizing gait center of pressure data

Hi Kathy,

I am Ann Hallemans from the University of Antwerp (Belgium) and have worked with pressure data (footscan) from toddler locomotion. I think your data analysis should depend on which questions you want to answer.

First about normalising the CoP data, in my opinion this would only make sense if indeed you have seperate data for the L/R feet. If you only have a combined CoP, there is no clear way to seperate the CoP for L/R. However, when using a pressure plate (which type?) most of the time you can select the feet and then there should be an option that gives you the CoP under each foot. What I calculated then, was the CoP path and I normalized this to foot length. In toddlers, you have quite some wobbling and this gave me a number >1. In normal adult gait this value was very close to 1.

I hope this helps you a bit, good luck with your data analysis.

Ann

[Kathleen Thomas]

Re: Normalizing gait center of pressure data

Ann,

Thank you for your response. That is very helpful. I was able to find the option to identify the right and left foot (the pressure plate is WinFDMT imbedded into a treadmill) separately. I am looking at the adaptive abilities in gait while walking at three different speeds. I am aware that there will be differences between the speeds but really want to see the changes over a prolonged period of time at a consistent pace. The use of COP path length will be helpful as well as excursion in both A/P and M/L positions.

Thank you,

Kathy