process of Metabolic Cost

[hongjie hou]

Hello everyone,

I want to know the detailed calculation process of Metabolic Cost. I do not know how to determine the ratio of slow- to fast-twitch fibers? I saw that the ratio shown in the opensim model file is fixed. However, in the relevant literature I found that this ratio is variable.
thanks,
hongjie

[Thomas Uchida]

I saw that the ratio shown in the opensim model file is fixed.

The ratio of slow- to fast-twitch fibers is a parameter: it can be set to any (constant) value for each muscle. Please see the documentation and references here: https://simtk.org/api_docs/opensim/api_ ... ml#details.

[hongjie hou]

Thank you very much for your help. Do you know how to determine the Scaling Factors(F_iso)?

[Thomas Uchida]

Do you know how to determine the Scaling Factors(F_iso)?

The image above appears to have been taken from Umberger et al., "A model of human muscle energy expenditure", 2003. The first sentence of the "Model derivation" section indicates that they are using a modified version of the muscle model described by van Soest and Bobbert (reference 1 in Umberger et al., 2003). A description of the muscle model (including F_iso) can be found in Appendix A.1 of van Soest and Bobbert.