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What is the difference between muscle activation and EMG?
Posted: Tue May 23, 2017 11:45 pm
by harisarkar
Hello
I was going through the paper by Darryl G. Thelen (Adjustment of Muscle Mechanics Model Parameters to simulate Dynamic Contractions in Older Adults 2003) and I noticed that muscle activation and EMG are different. Is it applicable to Opensim also?
Thank you
Re: What is the difference between muscle activation and EMG?
Posted: Wed May 24, 2017 12:37 am
by tkuchida
muscle activation and EMG are different. Is it applicable to Opensim also?
Yes. See, for example, Fig 2 in Hamner and Delp (2013) and the description thereof (Section 2.2, paragraph 2).
Hamner, S.R., Delp, S.L. (2013) Muscle contributions to fore-aft and vertical body mass center accelerations over a range of running speeds. Journal of Biomechanics 46:780–787.
http://nmbl.stanford.edu/publications/p ... er2012.pdf
Re: What is the difference between muscle activation and EMG?
Posted: Sat May 27, 2017 2:00 am
by harisarkar
How can I compare Activation to EMG or can I convert Activation to EMG?
Thank you
Re: What is the difference between muscle activation and EMG?
Posted: Sat May 27, 2017 1:41 pm
by tkuchida
How can I compare Activation to EMG or can I convert Activation to EMG?
Even after rectifying, filtering, and normalizing, EMG will still differ from activation because of the time delay between excitation and force generation. You could shift EMG in time, or report as it is and recognize that the delay between EMG and activation is expected. I recommend reading the literature to see how this has been approached.