OK, so I guess the Muscle Musical is well known enough that it can make mainstream news (the first two stories are in Japanese):
The first story is about a Muscle Musical member who is filing for compensation because she was hurt during the filming of an NHK show. The end of this story includes SASUKE and something about how the two shows were created by the same group and both HORRIBLY INJURE PEOPLE. Or maybe not. I could be exaggerating.
Edit: Here it is in English. For some reason, they left out that she was a Muscle Musical member.
This story is a bit old but it's about how three members of the troupe declined to join the Las Vegas troupe and then had their pay slashed and the union that was formed as a result. Here it is in English.
Finally, here is a month old story from the Japan Times Online about the creation of the show, one of the few in English.