# muscle activation determination from chartfx

Hi all,

I want to see muscle activation from Anybody compared to corresponding EMG data. However, a muscle envelope has several part in Anybody model, this is confusing me.
Whenever I want to see muscle force, then I just can sum up the forces within a muscle; i.e. the muscle force of deltoideus clavicular is the sum of Fm from deltoideus_clavicular_part_1~6 in chartfx.

In the case of muscle activation, I think that the average of muscle parts’ activation can be a muscle envelope’s activation when each part’s strength is all same; i.e. the activation of deltoideus clavicular is the average of Activity from deltoideus_clavicular_part_1~6 in chartfx.
The first question is if my assumption above is right to compare deltoideus clavicular’s EMG normalized by its MVC?

The second question is how I can derive the activation level of a muscle envelop from Anybody analysis result when each part’s strength value of one muscle is different?
Should I consider the strength value for calculating it or is there any other weight value to determine the each muscle part’s contribution for its envelop?

Dear Dong-Pyoung,

Comparing muscle activity and EMG is a difficult issue. It is not easy to compare values and shapes of the curves. However, it will give you a good extimate if there is a peak at the same time.
There are several papers out there comparing activity and EMG, there are also several posts in this Forum doing that. Additional, there is an example in application/validation in the repository named GaitVaughan having a comparison of Activity and EMG in it.

First question:
You can of course take an average value; however, most studies I know use an envelope of all muscle branches. Therefore I suggest you rather take the max value of all the muscles instead of an average.

Making EMG measurements is not easy and you never know if you get the muscle completely covered, so if you display all branches of the muscle and compare them to EMG, you will see if the individual peaks match with the EMG peaks…

If you take the average, you might have to include the strength, if you go with envelope of max activity, this will be covered already.

Hmm. that’s very difficult one.
Thank you for your answer and I need to see more in examples.