EMG and Muscle Activity.

Archive AnyScript Yahoo archive
1

Hi,

In the gait webcast, the result from the gait
simulation is compare with EMG result.

In particular, ‘Muscle Activation’ is compared
with EMG plot. Is the ‘muscle activation’ refer
to Muscle Activity or Corrected Activity?

I couldn’t find in the reference that say
the Muscle Activity or CorrectedActivity is
actually ‘equivalent’ to measured EMG data.

How is EMG measurement relate to AnyBody’s
muscle Activity and Corrected Activity?

It will be great if someone can point me
to a reference.

Thanks,
Leng-Feng Lee

________________________________________________________________________________\

Be a better friend, newshound, and
know-it-all with Yahoo! Mobile. Try it now.
http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

2

Hello.

In short, both EMG and AnyBody muscle (corr.) activity tell you when
within a certian movement a muscle is working.

And now to a slightly longer answer. Currently, there is no muscle
activation dynamics in AnyBody, at least partly due to nature of the
method. A muscle in AnyBody can produce maximum available* force
instantly (when the recruitment algorithm needs it). In reality, for
real muscles, there is a short delay. EMG measure the electric muscle
fiber action potential. When this potential jumps from it normal
value (about -90 mV) its a sign that the muscle is contracting and
producing force. There can be a delay here also which makes things
harder to interpret. Apart from the delay issue, I think there is
still a debate on how to interpret the EMG signal concerning its
relation to muscle force. Anyway, it is common to present EMG in % of
maximum voluntary force (for the specific muscle). To conclude, there
is no direct relation between AnyBody activity and EMG becasue a 0.5
AnyBody activity at one time instant is not the same as a 50% EMG
reading at the same time instant. But, in my opinion they are still
comparable at “larger scale” if you are aware of the differences.

*depending on current contraction velocity, length etc following the
Hill-type muscle model, or just max force with a simple muscle model.

See for example http://www.anybodytech.com/684.0.html for difference
of activity and corrected activity.

See for example http://en.wikipedia.org/wiki/Electromyography for EMG.

/jokke

— In anyscript@yahoogroups.com, Leng-Feng Lee <lengfenglee@…>
wrote:
>
> Hi,
>
> In the gait webcast, the result from the gait
> simulation is compare with EMG result.
>
> In particular, ‘Muscle Activation’ is compared
> with EMG plot. Is the ‘muscle activation’ refer
> to Muscle Activity or Corrected Activity?
>
> I couldn’t find in the reference that say
> the Muscle Activity or CorrectedActivity is
> actually ‘equivalent’ to measured EMG data.
>
> How is EMG measurement relate to AnyBody’s
> muscle Activity and Corrected Activity?
>
> It will be great if someone can point me
> to a reference.
>
> Thanks,
> Leng-Feng Lee
>
>
>
>
>
>

> Be a better friend, newshound, and
> know-it-all with Yahoo! Mobile. Try it now.
http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ
>

3

Hi Leng-Feng

The activities in the gait webcast is related to “Muscle Activity”.

To make comparison possible all the curves both the measured and the
calculated has been scaled unity, this is what is seen in the in the Gait
Modeling webcast of 21 june 2005.

In the muscle tutorial

http://www.anybodytech.com/179.0.html

There is the explanation of the “Corrected Activity”:

This is the muscle activity after correction for the tendon elongation. The
difference between this graph and the one above is that the activity toward
the end is higher after correction. This can be difficult to understand and
illustrates the complexity of muscle modeling. The reason is the following:
The force in the muscle reduces towards the end of the movement. When the
force is reduced, the tendon contracts, and this means that the muscle must
elongate even more. Since the muscle length is already in the interval where
further elongation will cause decreased strength, the tendon contraction has
the effect of increasing the muscle activity.

Best regards

Søren

From: anyscript@yahoogroups.com [mailto:anyscript@yahoogroups.com] On Behalf
Of Leng-Feng Lee
Sent: 19 April 2008 04:23
To: anyscript@yahoogroups.com
Subject: [AnyScript] EMG and Muscle Activity.

Hi,

In the gait webcast, the result from the gait
simulation is compare with EMG result.

In particular, ‘Muscle Activation’ is compared
with EMG plot. Is the ‘muscle activation’ refer
to Muscle Activity or Corrected Activity?

I couldn’t find in the reference that say
the Muscle Activity or CorrectedActivity is
actually ‘equivalent’ to measured EMG data.

How is EMG measurement relate to AnyBody’s
muscle Activity and Corrected Activity?

It will be great if someone can point me
to a reference.

Thanks,
Leng-Feng Lee

Be a better friend, newshound, and
know-it-all with Yahoo! Mobile. Try it now. http://mobile.
<http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ>
yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

[Non-text portions of this message have been removed]

4

Hi Jokke and Soren,

Thanks for the replies.

I guess Jokke reply confirm my understanding with
regarding to EMG and AnyBody Activity. Now my
question if there is a AnyBody publication (paper)
that talks about this?

Jokke is right that there is still a debate of how
EMG measurement relates to Muscle Forces,
Muscle mechanical work, metabolic cost, etc
in the literature. Is there a document (paper again)
that AnyBody document the comparison of its quantities
with those in used the Bio community (EMG, Oxygen
consumption, metabolic cost)? This will make
more sense if one wants to compare the results
from AnyBody with those in the Bio community.
(If something like this exist, please kindly point me
to the paper?)

Thank you (Soren, Jokke) for your reply. =)

-All comments are welcome.

Thanks,
Leng-Feng Lee

— On Mon, 4/21/08, joakim_holmberg <jokke@sockertoppen.com> wrote:
From: joakim_holmberg <jokke@sockertoppen.com>
Subject: [AnyScript] Re: EMG and Muscle Activity.
To: anyscript@yahoogroups.com
Date: Monday, April 21, 2008, 3:19 AM

         Hello.

In short, both EMG and AnyBody muscle (corr.) activity tell you when

within a certian movement a muscle is working.

And now to a slightly longer answer. Currently, there is no muscle

activation dynamics in AnyBody, at least partly due to nature of the

method. A muscle in AnyBody can produce maximum available* force

instantly (when the recruitment algorithm needs it). In reality, for

real muscles, there is a short delay. EMG measure the electric muscle

fiber action potential. When this potential jumps from it normal

value (about -90 mV) its a sign that the muscle is contracting and

producing force. There can be a delay here also which makes things

harder to interpret. Apart from the delay issue, I think there is

still a debate on how to interpret the EMG signal concerning its

relation to muscle force. Anyway, it is common to present EMG in % of

maximum voluntary force (for the specific muscle). To conclude, there

is no direct relation between AnyBody activity and EMG becasue a 0.5

AnyBody activity at one time instant is not the same as a 50% EMG

reading at the same time instant. But, in my opinion they are still

comparable at “larger scale” if you are aware of the differences.

*depending on current contraction velocity, length etc following the

Hill-type muscle model, or just max force with a simple muscle model.

See for example http://www.anybodyt ech.com/684. 0.html for difference

of activity and corrected activity.

See for example http://en.wikipedia .org/wiki/ Electromyography for EMG.

/jokke

— In anyscript@yahoogrou ps.com, Leng-Feng Lee <lengfenglee@ …>

wrote:

>

> Hi,

>

> In the gait webcast, the result from the gait

> simulation is compare with EMG result.

>

> In particular, ‘Muscle Activation’ is compared

> with EMG plot. Is the ‘muscle activation’ refer

> to Muscle Activity or Corrected Activity?

>

> I couldn’t find in the reference that say

> the Muscle Activity or CorrectedActivity is

> actually ‘equivalent’ to measured EMG data.

>

> How is EMG measurement relate to AnyBody’s

> muscle Activity and Corrected Activity?

>

> It will be great if someone can point me

> to a reference.

>

> Thanks,

> Leng-Feng Lee

>

>

>

>

>

>

> Be a better friend, newshound, and

> know-it-all with Yahoo! Mobile. Try it now.

http://mobile. yahoo.com/ ;_ylt=Ahu06i62sR 8HDtDypao8Wcj9tA cJ

>

________________________________________________________________________________\

Be a better friend, newshound, and
know-it-all with Yahoo! Mobile. Try it now.
http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

5

Hi Leng-Feng

I am sorry, but there are no such paper that I know of :wink:

Best regards

Søren

From: anyscript@yahoogroups.com [mailto:anyscript@yahoogroups.com] On Behalf
Of Leng-Feng Lee
Sent: 21 April 2008 18:14
To: anyscript@yahoogroups.com
Subject: Re: [AnyScript] Re: EMG and Muscle Activity.

Hi Jokke and Soren,

Thanks for the replies.

I guess Jokke reply confirm my understanding with
regarding to EMG and AnyBody Activity. Now my
question if there is a AnyBody publication (paper)
that talks about this?

Jokke is right that there is still a debate of how
EMG measurement relates to Muscle Forces,
Muscle mechanical work, metabolic cost, etc
in the literature. Is there a document (paper again)
that AnyBody document the comparison of its quantities
with those in used the Bio community (EMG, Oxygen
consumption, metabolic cost)? This will make
more sense if one wants to compare the results
from AnyBody with those in the Bio community.
(If something like this exist, please kindly point me
to the paper?)

Thank you (Soren, Jokke) for your reply. =)

-All comments are welcome.

Thanks,
Leng-Feng Lee

— On Mon, 4/21/08, joakim_holmberg <jokke@sockertoppen.
<mailto:jokke%40sockertoppen.com> com> wrote:
From: joakim_holmberg <jokke@sockertoppen. <mailto:jokke%40sockertoppen.com>
com>
Subject: [AnyScript] Re: EMG and Muscle Activity.
To: anyscript@yahoogrou <mailto:anyscript%40yahoogroups.com> ps.com
Date: Monday, April 21, 2008, 3:19 AM

Hello.

In short, both EMG and AnyBody muscle (corr.) activity tell you when

within a certian movement a muscle is working.

And now to a slightly longer answer. Currently, there is no muscle

activation dynamics in AnyBody, at least partly due to nature of the

method. A muscle in AnyBody can produce maximum available* force

instantly (when the recruitment algorithm needs it). In reality, for

real muscles, there is a short delay. EMG measure the electric muscle

fiber action potential. When this potential jumps from it normal

value (about -90 mV) its a sign that the muscle is contracting and

producing force. There can be a delay here also which makes things

harder to interpret. Apart from the delay issue, I think there is

still a debate on how to interpret the EMG signal concerning its

relation to muscle force. Anyway, it is common to present EMG in % of

maximum voluntary force (for the specific muscle). To conclude, there

is no direct relation between AnyBody activity and EMG becasue a 0.5

AnyBody activity at one time instant is not the same as a 50% EMG

reading at the same time instant. But, in my opinion they are still

comparable at “larger scale” if you are aware of the differences.

*depending on current contraction velocity, length etc following the

Hill-type muscle model, or just max force with a simple muscle model.

See for example http://www.anybodyt ech.com/684. 0.html for difference

of activity and corrected activity.

See for example http://en.wikipedia .org/wiki/ Electromyography for EMG.

/jokke

— In anyscript@yahoogrou ps.com, Leng-Feng Lee <lengfenglee@ …>

wrote:

>

> Hi,

>

> In the gait webcast, the result from the gait

> simulation is compare with EMG result.

>

> In particular, ‘Muscle Activation’ is compared

> with EMG plot. Is the ‘muscle activation’ refer

> to Muscle Activity or Corrected Activity?

>

> I couldn’t find in the reference that say

> the Muscle Activity or CorrectedActivity is

> actually ‘equivalent’ to measured EMG data.

>

> How is EMG measurement relate to AnyBody’s

> muscle Activity and Corrected Activity?

>

> It will be great if someone can point me

> to a reference.

>

> Thanks,

> Leng-Feng Lee

>

>

>

>

>

>

> Be a better friend, newshound, and

> know-it-all with Yahoo! Mobile. Try it now.

http://mobile. yahoo.com/ ;_ylt=Ahu06i62sR 8HDtDypao8Wcj9tA cJ

>

Be a better friend, newshound, and
know-it-all with Yahoo! Mobile. Try it now. http://mobile.
<http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ>
yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

[Non-text portions of this message have been removed]

6

Hej Leng-Feng Lee,

Maybe the following paper might give you some leads:

de Zee M, Dalstra M, Cattaneo PM, Rasmussen J, Svensson P, Melsen B.
Validation of a musculo-skeletal model of the mandible and its
application to mandibular distraction osteogenesis.
J Biomech. 2007;40(6):1192-201.

URL: http://dx.doi.org/10.1016/j.jbiomech.2006.06.024

In this paper we have validated a mandible model built in AnyBody with
EMG recordings (both surface and wire electrodes).

Greetings, Mark

Leng-Feng Lee wrote:
>
> Hi Jokke and Soren,
>
> Thanks for the replies.
>
> I guess Jokke reply confirm my understanding with
> regarding to EMG and AnyBody Activity. Now my
> question if there is a AnyBody publication (paper)
> that talks about this?
>
> Jokke is right that there is still a debate of how
> EMG measurement relates to Muscle Forces,
> Muscle mechanical work, metabolic cost, etc
> in the literature. Is there a document (paper again)
> that AnyBody document the comparison of its quantities
> with those in used the Bio community (EMG, Oxygen
> consumption, metabolic cost)? This will make
> more sense if one wants to compare the results
> from AnyBody with those in the Bio community.
> (If something like this exist, please kindly point me
> to the paper?)
>
> Thank you (Soren, Jokke) for your reply. =)
>
> -All comments are welcome.
>
> Thanks,
> Leng-Feng Lee
>
> — On Mon, 4/21/08, joakim_holmberg <jokke@sockertoppen.com
> <mailto:jokke%40sockertoppen.com>> wrote:
> From: joakim_holmberg <jokke@sockertoppen.com
> <mailto:jokke%40sockertoppen.com>>
> Subject: [AnyScript] Re: EMG and Muscle Activity.
> To: anyscript@yahoogroups.com <mailto:anyscript%40yahoogroups.com>
> Date: Monday, April 21, 2008, 3:19 AM
>
> Hello.
>
> In short, both EMG and AnyBody muscle (corr.) activity tell you when
>
> within a certian movement a muscle is working.
>
> And now to a slightly longer answer. Currently, there is no muscle
>
> activation dynamics in AnyBody, at least partly due to nature of the
>
> method. A muscle in AnyBody can produce maximum available* force
>
> instantly (when the recruitment algorithm needs it). In reality, for
>
> real muscles, there is a short delay. EMG measure the electric muscle
>
> fiber action potential. When this potential jumps from it normal
>
> value (about -90 mV) its a sign that the muscle is contracting and
>
> producing force. There can be a delay here also which makes things
>
> harder to interpret. Apart from the delay issue, I think there is
>
> still a debate on how to interpret the EMG signal concerning its
>
> relation to muscle force. Anyway, it is common to present EMG in % of
>
> maximum voluntary force (for the specific muscle). To conclude, there
>
> is no direct relation between AnyBody activity and EMG becasue a 0.5
>
> AnyBody activity at one time instant is not the same as a 50% EMG
>
> reading at the same time instant. But, in my opinion they are still
>
> comparable at “larger scale” if you are aware of the differences.
>
> *depending on current contraction velocity, length etc following the
>
> Hill-type muscle model, or just max force with a simple muscle model.
>
> See for example http://www.anybodyt ech.com/684. 0.html for difference
>
> of activity and corrected activity.
>
> See for example http://en.wikipedia .org/wiki/ Electromyography for EMG.
>
> /jokke
>
> — In anyscript@yahoogrou ps.com, Leng-Feng Lee <lengfenglee@ …>
>
> wrote:
>
> >
>
> > Hi,
>
> >
>
> > In the gait webcast, the result from the gait
>
> > simulation is compare with EMG result.
>
> >
>
> > In particular, ‘Muscle Activation’ is compared
>
> > with EMG plot. Is the ‘muscle activation’ refer
>
> > to Muscle Activity or Corrected Activity?
>
> >
>
> > I couldn’t find in the reference that say
>
> > the Muscle Activity or CorrectedActivity is
>
> > actually ‘equivalent’ to measured EMG data.
>
> >
>
> > How is EMG measurement relate to AnyBody’s
>
> > muscle Activity and Corrected Activity?
>
> >
>
> > It will be great if someone can point me
>
> > to a reference.
>
> >
>
> > Thanks,
>
> > Leng-Feng Lee
>
> >
>
> >
>
> >
>
> >
>
> >
>
> >
>
> ____________ _________ _________ _________ _________ _________ _
>
> ____________ __
>
> > Be a better friend, newshound, and
>
> > know-it-all with Yahoo! Mobile. Try it now.
>
> http://mobile. yahoo.com/ ;_ylt=Ahu06i62sR 8HDtDypao8Wcj9tA cJ
>
> >
>
>
>
>
>
>
>
>
>
>
>
> __________________________________________________________
> Be a better friend, newshound, and
> know-it-all with Yahoo! Mobile. Try it now.
> http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ
> <http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ>
>
>

7

Hello.

What about the following:

Thompson, M.S., M. Voigt, and M. de Zee.: Evaluation of lower extremity
musculo-skeletal model using sit-to-stand movement. In: Milburn, P.
(ed.), University of Otago, International Society of Biomechanics XIXth
Congress : the human body in motion, 6-11 July 2003, Dunedin New
Zealand, Dunedin, N.Z., University of Otago, 2003, CD ROM Abstracts and
Proceedings.

Though, if I remember correctly, its a staight forward comparison of EMG
and AnyBody simulated activity and no discussion about the “correctness”
of such a comparison.

/jokke

— In anyscript@yahoogroups.com, Mark de Zee <mdz@…> wrote:
>
> Hej Leng-Feng Lee,
>
> Maybe the following paper might give you some leads:
>
> de Zee M, Dalstra M, Cattaneo PM, Rasmussen J, Svensson P, Melsen B.
> Validation of a musculo-skeletal model of the mandible and its
> application to mandibular distraction osteogenesis.
> J Biomech. 2007;40(6):1192-201.
>
> URL: http://dx.doi.org/10.1016/j.jbiomech.2006.06.024
>
> In this paper we have validated a mandible model built in AnyBody with
> EMG recordings (both surface and wire electrodes).
>
> Greetings, Mark
>
> Leng-Feng Lee wrote:
> >
> > Hi Jokke and Soren,
> >
> > Thanks for the replies.
> >
> > I guess Jokke reply confirm my understanding with
> > regarding to EMG and AnyBody Activity. Now my
> > question if there is a AnyBody publication (paper)
> > that talks about this?
> >
> > Jokke is right that there is still a debate of how
> > EMG measurement relates to Muscle Forces,
> > Muscle mechanical work, metabolic cost, etc
> > in the literature. Is there a document (paper again)
> > that AnyBody document the comparison of its quantities
> > with those in used the Bio community (EMG, Oxygen
> > consumption, metabolic cost)? This will make
> > more sense if one wants to compare the results
> > from AnyBody with those in the Bio community.
> > (If something like this exist, please kindly point me
> > to the paper?)
> >
> > Thank you (Soren, Jokke) for your reply. =)
> >
> > -All comments are welcome.
> >
> > Thanks,
> > Leng-Feng Lee
> >
> > — On Mon, 4/21/08, joakim_holmberg jokke@…
> > <mailto:jokke%40sockertoppen.com>> wrote:
> > From: joakim_holmberg jokke@…
> > <mailto:jokke%40sockertoppen.com>>
> > Subject: [AnyScript] Re: EMG and Muscle Activity.
> > To: anyscript@yahoogroups.com <mailto:anyscript%40yahoogroups.com>
> > Date: Monday, April 21, 2008, 3:19 AM
> >
> > Hello.
> >
> > In short, both EMG and AnyBody muscle (corr.) activity tell you when
> >
> > within a certian movement a muscle is working.
> >
> > And now to a slightly longer answer. Currently, there is no muscle
> >
> > activation dynamics in AnyBody, at least partly due to nature of the
> >
> > method. A muscle in AnyBody can produce maximum available* force
> >
> > instantly (when the recruitment algorithm needs it). In reality, for
> >
> > real muscles, there is a short delay. EMG measure the electric
muscle
> >
> > fiber action potential. When this potential jumps from it normal
> >
> > value (about -90 mV) its a sign that the muscle is contracting and
> >
> > producing force. There can be a delay here also which makes things
> >
> > harder to interpret. Apart from the delay issue, I think there is
> >
> > still a debate on how to interpret the EMG signal concerning its
> >
> > relation to muscle force. Anyway, it is common to present EMG in %
of
> >
> > maximum voluntary force (for the specific muscle). To conclude,
there
> >
> > is no direct relation between AnyBody activity and EMG becasue a 0.5
> >
> > AnyBody activity at one time instant is not the same as a 50% EMG
> >
> > reading at the same time instant. But, in my opinion they are still
> >
> > comparable at “larger scale” if you are aware of the differences.
> >
> > *depending on current contraction velocity, length etc following the
> >
> > Hill-type muscle model, or just max force with a simple muscle
model.
> >
> > See for example http://www.anybodyt ech.com/684. 0.html for
difference
> >
> > of activity and corrected activity.
> >
> > See for example http://en.wikipedia .org/wiki/ Electromyography for
EMG.
> >
> > /jokke
> >
> > — In anyscript@yahoogrou ps.com, Leng-Feng Lee <lengfenglee@ …>
> >
> > wrote:
> >
> > >
> >
> > > Hi,
> >
> > >
> >
> > > In the gait webcast, the result from the gait
> >
> > > simulation is compare with EMG result.
> >
> > >
> >
> > > In particular, ‘Muscle Activation’ is compared
> >
> > > with EMG plot. Is the ‘muscle activation’ refer
> >
> > > to Muscle Activity or Corrected Activity?
> >
> > >
> >
> > > I couldn’t find in the reference that say
> >
> > > the Muscle Activity or CorrectedActivity is
> >
> > > actually ‘equivalent’ to measured EMG data.
> >
> > >
> >
> > > How is EMG measurement relate to AnyBody’s
> >
> > > muscle Activity and Corrected Activity?
> >
> > >
> >
> > > It will be great if someone can point me
> >
> > > to a reference.
> >
> > >
> >
> > > Thanks,
> >
> > > Leng-Feng Lee
> >
> > >
> >
> > >
> >
> > >
> >
> > >
> >
> > >
> >
> > >
> >
> > ____________ _________ _________ _________ _________ _________ _
> >
> > ____________ __
> >
> > > Be a better friend, newshound, and
> >
> > > know-it-all with Yahoo! Mobile. Try it now.
> >
> > http://mobile. yahoo.com/ ;_ylt=Ahu06i62sR 8HDtDypao8Wcj9tA cJ
> >
> > >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > __________________________________________________________
> > Be a better friend, newshound, and
> > know-it-all with Yahoo! Mobile. Try it now.
> > http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ
> > <http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ>
> >
> >
>

[Non-text portions of this message have been removed]

8

Hi Leng-Feng,

I am currently doing some gait modelling with simultaneous EMG data collection.
I am a couple of weeks away from sorting my data out, but I’d be happy to pass
over some examples when i do.

best wishes

peter

AnyBody Support <support@anybodytech.com> wrote:

Hi Leng-Feng

I am sorry, but there are no such paper that I know of :wink:

Best regards

Søren

From: anyscript@yahoogroups.com [mailto:anyscript@yahoogroups.com] On Behalf
Of Leng-Feng Lee
Sent: 21 April 2008 18:14
To: anyscript@yahoogroups.com
Subject: Re: [AnyScript] Re: EMG and Muscle Activity.

Hi Jokke and Soren,

Thanks for the replies.

I guess Jokke reply confirm my understanding with
regarding to EMG and AnyBody Activity. Now my
question if there is a AnyBody publication (paper)
that talks about this?

Jokke is right that there is still a debate of how
EMG measurement relates to Muscle Forces,
Muscle mechanical work, metabolic cost, etc
in the literature. Is there a document (paper again)
that AnyBody document the comparison of its quantities
with those in used the Bio community (EMG, Oxygen
consumption, metabolic cost)? This will make
more sense if one wants to compare the results
from AnyBody with those in the Bio community.
(If something like this exist, please kindly point me
to the paper?)

Thank you (Soren, Jokke) for your reply. =)

-All comments are welcome.

Thanks,
Leng-Feng Lee

— On Mon, 4/21/08, joakim_holmberg
com> wrote:
From: joakim_holmberg
com>
Subject: [AnyScript] Re: EMG and Muscle Activity.
To: anyscript@yahoogrou ps.com
Date: Monday, April 21, 2008, 3:19 AM

Hello.

In short, both EMG and AnyBody muscle (corr.) activity tell you when

within a certian movement a muscle is working.

And now to a slightly longer answer. Currently, there is no muscle

activation dynamics in AnyBody, at least partly due to nature of the

method. A muscle in AnyBody can produce maximum available* force

instantly (when the recruitment algorithm needs it). In reality, for

real muscles, there is a short delay. EMG measure the electric muscle

fiber action potential. When this potential jumps from it normal

value (about -90 mV) its a sign that the muscle is contracting and

producing force. There can be a delay here also which makes things

harder to interpret. Apart from the delay issue, I think there is

still a debate on how to interpret the EMG signal concerning its

relation to muscle force. Anyway, it is common to present EMG in % of

maximum voluntary force (for the specific muscle). To conclude, there

is no direct relation between AnyBody activity and EMG becasue a 0.5

AnyBody activity at one time instant is not the same as a 50% EMG

reading at the same time instant. But, in my opinion they are still

comparable at “larger scale” if you are aware of the differences.

*depending on current contraction velocity, length etc following the

Hill-type muscle model, or just max force with a simple muscle model.

See for example http://www.anybodyt ech.com/684. 0.html for difference

of activity and corrected activity.

See for example http://en.wikipedia .org/wiki/ Electromyography for EMG.

/jokke

— In anyscript@yahoogrou ps.com, Leng-Feng Lee

wrote:

>

> Hi,

>

> In the gait webcast, the result from the gait

> simulation is compare with EMG result.

>

> In particular, ‘Muscle Activation’ is compared

> with EMG plot. Is the ‘muscle activation’ refer

> to Muscle Activity or Corrected Activity?

>

> I couldn’t find in the reference that say

> the Muscle Activity or CorrectedActivity is

> actually ‘equivalent’ to measured EMG data.

>

> How is EMG measurement relate to AnyBody’s

> muscle Activity and Corrected Activity?

>

> It will be great if someone can point me

> to a reference.

>

> Thanks,

> Leng-Feng Lee

>

>

>

>

>

>

> Be a better friend, newshound, and

> know-it-all with Yahoo! Mobile. Try it now.

http://mobile. yahoo.com/ ;_ylt=Ahu06i62sR 8HDtDypao8Wcj9tA cJ

>

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9

— In anyscript@yahoogroups.com, Leng-Feng Lee <lengfenglee@…> wrote:

> Is there a document (paper again)
> that AnyBody document the comparison
> of its quantities with those in used
> the Bio community (EMG, Oxygen
> consumption, metabolic cost)?

Hi Leng-Feng,

There is actually exactly such a paper, although it is not about
AnyBody. Marit Praagman from the Free University of Amsterdam is
defending her PhD thesis on April 22nd, and in the thesis is this paper:

M. Praagman, H.E.J Veeger, E.K.J. Chadwick, W.N.J.M Coller & F.C.T. van
der Helm: Muscle oxygen consumption, determined by NIRS, in relation to
external force and EMG. Journal of Biomechanics, 36(7), pp. 905-912,
2003.

I think that is pretty much what you are looking for.

Best regards,
John

10

Hi,

Thanks (John, jokke, Mark, and Soren) who reply
and provide useful references.

Praagman’s paper shows linear relationship between
EMG, Oxygen Consumption (local) measurement
linearly correlate to each other and also linearly
related to external load - hence likely linearly related
to muscle forces.

AnyBody’s Muscle Activity value, on the other hand,
have shown comparable patterns with EMG measure-
ment in Mark’s paper (and others).

Thanks again for everyone who reply!

Sincerely,
Leng-Feng Lee

— On Tue, 4/22/08, John Rasmussen <jr@ime.aau.dk> wrote:
From: John Rasmussen <jr@ime.aau.dk>
Subject: [AnyScript] Re: EMG and Muscle Activity.
To: anyscript@yahoogroups.com
Date: Tuesday, April 22, 2008, 3:42 PM

         --- In anyscript@yahoogrou ps.com, Leng-Feng Lee &lt;lengfenglee@ ...&gt;

wrote:

> Is there a document (paper again)

> that AnyBody document the comparison

> of its quantities with those in used

> the Bio community (EMG, Oxygen

> consumption, metabolic cost)?

Hi Leng-Feng,

There is actually exactly such a paper, although it is not about

AnyBody. Marit Praagman from the Free University of Amsterdam is

defending her PhD thesis on April 22nd, and in the thesis is this paper:

M. Praagman, H.E.J Veeger, E.K.J. Chadwick, W.N.J.M Coller & F.C.T. van

der Helm: Muscle oxygen consumption, determined by NIRS, in relation to

external force and EMG. Journal of Biomechanics, 36(7), pp. 905-912,

I think that is pretty much what you are looking for.

Best regards,

John

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