Ballerina bodycheck

They are not ballerinas. The are Chinese Traditional Dancers (古典舞), which was invented in 1950s partly modeled on ballet hence the confusion. For one thing they don't use pointe shoes. And they really like to focus on back flexibility - they are usually as flexible as rhythmic gymnasts. Lots of torture videos on YouTube of their passive flexibility training (big no no in the ballet world which encourages active stretching instead).