Muscle Envelope force range

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1

Hi There,

I am currently analysing some data and assessing the muscle envelopes of the trunk, shoulder and legs. A lot of the time the data exceeds values between 0-1. I am wanting to clarify what the value is in the muscle envelope in terms of the axis. I originally assumed between 0-1 was total force range of the muscle?

Thank-you,
Darius

2

Hi Darius,
Muscle activation is force in muscle divided by its strength, so normally between 0 and 1.

The solver will allow it to exceed one if needed, meaning that the model is overloaded.

The overloading can come from applied external loads or the dynamics of the motion or scaling etc…

Best regards
Søren

3

Hi Soren,

Thank-you for your reply.
Would this mean the results are still valid if errors etc. and parameters are correct?

Meaning the values that exceed 1 are a correct result of muscle activation force in the muscle divided by its strength greater than what is capable within the the models muscle capacity parameters?
Being that it is a factor of external force, but still the correct values resulting on the model.

Or is it just an error once it exceeds 1?

Kind Regards,
Darius

4

Hi Darius,

The result is still correct in the sense that dynamic equilibrium has been obtained etc., but the criterium may have changed.

A little more explanation:
If the upperbound of 1 enabled in the study and e.g power criteria of 3, then when the activation of 1 is reached the solver will try to find a solution not exceeding 1, if this turns out to be not possible it will shift to the min max strict criterium, which in theory always extract the maximum strength from the model.

Please see more details on this in this tutorial :
https://anyscript.org/tutorials/MuscleRecruitment/index.html

Best regards
Søren

5

Hi Soren,

Thankyou for the explanation, that has been very helpful.

Kind Regards,
Darius

6

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