In Degas's numerous paintings of ballet dancers there is always this atmosphere of women concentrated in themselves. It is not a place where the dancers talk to each other about their problems or victories.
It seems they are thinking if the clothes are well adjusted, if their postures are fine, movements correct, everything related with their own performances.
They are self-conscious an maybe fearing any tiny little thing wrong can ruin it all.
I don't know why for me they always finish in standing ovation.