Muscle Contributions to Centre of Mass Acceleration


For my research project I would like to calculate muscle contributions to the acceleration of the whole body centre of mass (CoM). I have seen that it has been achieved using induced acceleration analysis to estimate muscle contributions to propulsion and support during running using OpenSim. In this method the net ground reaction force was decomposed into individual muscle constituents to determine how muscles accelerate the whole body CoM.

Can a similar method be performed using the AnyBody Modeling System? If not, is there another method that can be implemented in AnyBody to calculate muscle contributions to the acceleration of the whole body centre of mass?

Thanks for your help.

Dear Paul,

First of all, I’d like to apologize for the belated response. We had an internal discussion here last week about this. The conclusion is that although it can be implemented in the AnyBody Modelling System, currently we don’t have it for users.

Nevertheless, we recommend a couple of alternative approaches that we think can be easily used:
1- If you have measured ground reaction forces (GRFs), run inverse dynamics once to get muscle forces. Then, add 1 N of directional force to one of the GRFs at a time and run the analysis again to get the second set of muscle forces. By comparing the two sets of forces, you will be able to compute the contribution of each muscle to each GRF component and somehow implicitly to the COM acceleration.
2- If you are using our ground reaction force prediction (that can be used to predict any environment force in general), you can add unit directional force to the center of mass (CoM) using AnyKinCoM and run the second analysis with this. This will provide you with the contribution of force of each muscle to the CoM directional acceleration.

The above-mentioned approaches in principle lead to different results than those from the Induced Acceleration Method because the directional perturbation force will be distributed to all muscles during the muscle recruitment algorithm; however, we believe that they convey physiological meaning.

Hope you find this useful.

Best Regards,
Mohammad S. Shourijeh, PhD
ANyBody Team