What do you suppose those computers are doing, then? ;)

https://www.youtube.com/watch?v=tF4DML7FIWk

https://www.youtube.com/watch?v=tfb6aEUMC04&t=115s

I would go a step further and look at the research on medical devices for spinal-damage patients which try to literally control their existing muscles through a computer; the concept of neuroprosthesis and https://en.wikipedia.org/wiki/Functional_electrical_stimulat... working to design algorithms on CPU to move muscles, as the parent post words it.

In this very narrow sense that you are defining, no brain can move a muscle either. All it can do is send signals. A computer can do the same.

If you are making a broader claim about the limits of hardware vs. wetware the you will need to clarify things a bit further.

This is such a strange claim to make, I can't even tell what you could have meant. We are surrounded by simplistic mechanical computations moving muscles , and have been for more than a hundred years, since the industrial revolution at least.