Is Dark Matter good for building muscle?
Dark Matter has got nothing to do with building muscle! It's
"stuff" that may not even exist!
It's usually ok, just be careful of spontaneous black holes and
blinking out of existence.
Another view: If dark matter does exist and has the
properties postulated by cosmologists, then it would be no good for
building muscle. It interacts so weakly with ordinary matter that
you would be unable to lift it - it would pass right through