EMG synchronization with single Gait cycle

[Syed Wasim]

Hi,

I am working on my PhD research project related with the gait analysis of the patients with hip surgeries. I used Vicon® motion capturing system for gait data. I also collect the EMG from the lower limb muscles. I used some radio sync device to synchronized the EMG with gait cycle. Unfortunately for some of my subjects the synch does not worked and I did not got any synch signal. I am wondering how to used these subject. My question is how could I detect or synchronized my gait data and EMG data?

[Edmund Cramp]

Re: EMG synchronization with single Gait cycle

... I used some radio sync device to synchronized the EMG with gait cycle. Unfortunately for some of my subjects the synch does not worked and I did not got any synch signal. I am wondering how to used these subject. My question is how could I detect or synchronized my gait data and EMG data?

I think that what you are asking is "Can I synchronize my EMG and kinematic data by simply looking at the recorded EMG signal to determine gait events?"

I'm sorry to say that the answer is no - certainly you could look at the EMG and say "that looking like heel contact" and while that assessment might be reasonable for one subject it would be impossible to say that this was "synchronization" with data between different subjects. Even if you can see a heel-strike artifact in the data, and use the heel strike artifact to guess at the gait cycle timing, I think that it would still be impossible to compare data from different subjects with any degree of confidence for research.

An additional factor that you may need to take into account if you are using a radio-telemetry EMG system is that many of these radio-telemetry systems introduce significant delays between the EMG signal detection at the skin surface, and the arrival of the signal at the Motion Capture system ADC - EMG signal delays of 16-48ms are common, resulting in the EMG data lagging the kinematic data at the ADC inputs.

You may also need to confirm that your radio sync method does not introduce a similar delay.

[Ross Miller]

Re: EMG synchronization with single Gait cycle

Hi Wasim,

I agree with Edmund that it will be very difficult if not impossible to manually synch your data.

If there's a timestamp on the raw data files, that may be a place to start, but even then they will very likely not be truly synched as the stamp usually just tells you when the file was created, not when the first data point was sampled.

Good luck,
Ross

[Syed Wasim]

Re: EMG synchronization with single Gait cycle

Hi Wasim,

I agree with Edmund that it will be very difficult if not impossible to manually synch your data.

If there's a timestamp on the raw data files, that may be a place to start, but even then they will very likely not be truly synched as the stamp usually just tells you when the file was created, not when the first data point was sampled.

Good luck,
Ross

thanks for reply. I am thinking that it is not possible.

[Syed Wasim]

Re: EMG synchronization with single Gait cycle

yes you people are right. It looks very hard to synchronized EMG data with gait data. I am wandering whether is there some Matlab program which can help me to detect or synchronised this data..

Many thanks for the replies.

[Ton van den Bogert]

Re: EMG synchronization with single Gait cycle

Wasim,

A quick note from the moderator. On Biomch-L, we require that everyone uses their full real name. Please click on "Settings" (top right of screen), then "Edit Profile" (left side of screen), and type your first name and last name in the "Real Name" box.

While not required, it is also useful to have a signature that identifies where you work, etc. This is in "Edit Signature".

And thanks for asking the question. It was good to see that some of our senior members did their best to help you.

Ton van den Bogert, Biomch-L co-moderator