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Hello,
I am working on calculating metabolic cost when arm26 model lifts a load of 0kg, 1kg and 2kg from 0 degree elbow flexion to 95 degrees elbow flexion. So, this is the plot I obtained of total metabolic cost. But here I see that the metabolic rate curve for 2kg load is coming at some points even lower than that of 1kg and 0kg load. I don't understand this because with increasing the load, muscle forces are increasing and so are the muscle activations, and since metabolic cost is direct function of these quantities, it should also increase at every point. So, curves for 0kg, 1kg and 2kg loads either have to be parallel to each other with enough separation between them or if not linear then at least enough separation has to be there with no crossings.

Now, when I remove include_negative_mechanical_work_rate, the results are coming exactly as expected. I have read the Bhargava and Umberger models for metabolic cost estimation, but I am not getting able to understand what this negative_mechanical_work_rate is.

If someone has some idea regarding this the please help.

Thanks,
Ratna Sambhav

This parameter is described in the API documentation for Umberger2010MuscleMetabolicsProbe, under the "MECHANICAL WORK RATE (W)" heading (https://simtk.org/api_docs/opensim/api_ ... ml#details). Additional discussion can be found in the papers listed there.