weightage of forces in a muscle spindle/group

Dear experts,

As mentioned in the subject, my question is related to how force gets distributed among multiple functional groups of a muscle.

So, for example, the calf muscle has three functional groups (two heads of the gastroc + soleus). When AnyBody solves the indeterminate problem, how does it make sure the max. muscle force from the entire muscle (i.e., the whole calf muscle) is not physiologically unreasonable?

For instance, in a recent seminar by AnyBody (knee grand challenge), the forces were weighted by the fractional volume? In the latest version, this is NOT being done.

Thank you,


Dear Vikas,

[COLOR=black]The current version of AMS incorporates the features needed to handle the normalization which was used in the knee grand challenge, the feature is available, but it has not been implemented into the models yet. [/COLOR]

[COLOR=black]Take a look at the AnyBodyStudy object in the reference manual and look for the “[/COLOR]Nfactor_SearchName[COLOR=black]” terms[/COLOR]

[COLOR=black]The procedure is to add the normalization factor to each muscle in the model which is picked up by the recruitment solver.[/COLOR]
[COLOR=black]So in each muscle you write eg. AnyVar MyNormalizationTerm =xxx[/COLOR]
[COLOR=black]And in the anybody study you define the Nfactor_searhname(s) = MyNormalizationTerm[/COLOR]

[COLOR=black]I do not have any examples on hand I can provide, if it is something you would like to try I would start playing with it on the simple arm model to understand how it works… [/COLOR]

In general the recruitment solver see each muscle unit independently there is no activation constraints relating activities between muscles, but this is also possible to add in the study that muscle are activated in a linear combination.

It is also possible to add upperbound activation on muscles individually or in general for all muscles.

I do not think there is a direct way to say that the combined force from three muscles must be less than a certain number. Constraints can be made on the activation levels directly but not on their force. It would however be possible to create a dummy segment which the muscle attach to and then constrain the reaction in this jnt to be less than a certain number.

Best regards

Dear Soren,

i have one rather simple question. I just wanted to ask where the Normalization Factor i can define by myself will actually work.
Is it correct to assume that the Muscle Recruitment will try to minimize the following formula in equation.png?

Thanks in advance,