Leg muscles’ force as a system of levers

[KataruZ98]

TL;DR Summary

How can I calculate the force exerted by each muscle group in a jump?

If I know a person has exerted total force F with their legs and I’m interested in breaking down said force in smaller forces exerted for each involved muscle group - how can I do it? With a basic level of understanding of human anatomy I can divide the leg as a series of levers but how can I specifically find force exerted by each lever?

EDIT: I’m aware “smaller” is not the correct word, but still..

 

[A.T.]

If I know a person has exerted total force F with their legs and I’m interested in breaking down said force in smaller forces exerted for each involved muscle group - how can I do it? With a basic level of understanding of human anatomy I can divide the leg as a series of levers but how can I specifically find force exerted by each lever?

Note that this is an underdetermined problem, so you need to specify an optimization criterion to get a unique solution. You use inverse-dynamics to get the external joint torques from the ground reaction force, and then muscle optimization to get the muscle forces that balance these external torques.

You can use software for that:
https://simtk.org/projects/opensim

If you simplify it to 2D and just a few muscles, then you might get something that you can solve by hand.

 

[KataruZ98]

Note that this is an undermined problem, so you need to specify an optimization criterion to get a unique solution. You use inverse-dynamics to get the external joint torques from the ground reaction force, and then muscle optimization to get the muscle forces that balance these external torques.

You can use software for that:
https://simtk.org/projects/opensim

If you simplify it to 2D and just a few muscles, then you might get something that you can solve by hand.

Ah, I see. Thank you very much, I’ll see what I’ll be able to do.

 

[jbriggs444]

undermined

I suspect that the correct word is underdetermined.

There are some nasty repetitions in there to entice the fingers to skip ahead in the sequence and no spell check to save you.

 

[A.T.]

I suspect that the correct word is underdetermined.

Yes, thanks. Fixed it.