Is there an 'angel dance' outside of the Shirobako anime?
According to what I read in a forum:


  Ema's Angel Exercise is modelled on the real-life Angel Exercise in the 70s.
  Bodybuilder Tsushima Seiji, under the name of Mukimuki Man (Muscular Man), comically did the Angel Exercise in the TV commercial for a sweet made by Morinaga and also in other TV programmes in the late 70s. (Morinaga's mascot is an angel, and the founder of Morinaga &amp; Company Morinaga Taichirō was a Christian and learnt how to make Western-style confectionery in the USA.)


Here's the video of the original Angel Exercise: https://www.youtube.com/watch?v=NpF9V3nQoK4