The illusion of dance on stage: constructing a fourth wall separating yourself, the dancer, from the audience, becoming an elusive creature as part of a narrative performance and executing the choreography to such a high standard it could not possibly have been done by a human. All three of these reasons for illusions are just some which help to evoke a sense of magic on stage, convincing the audience of the magic of the theatre of which you are both part of.
The feeling of being in the presence of a non-human illusion by the audience is usually through the dancer performing the steps and choreography to such a high standard that is incomparable to anything from the audience's day-to-day life. For the dancer, performing on stage usually feels very different to how it looks; remembering the next sections of choreography, staying 'on your leg' and making sure you perform as well on stage as you did in rehearsals are all big parts of conveying a performance. Lots of preparation is done throughout rehearsals, making sure the body is ready for what the piece requires from the dancer.
In this sense, core conditioning is a vastly important part of the rehearsals and off-stage preparations. If the body is strong and able, executing the choreography is wholly easier. Many dancers undertake conditioning exercises such as gym work and the use of weights in order to define their muscles further. However, the most important part of this, for on-stage success, is utilising the core efficiently, having built up the deep stomach muscles to create a strong base to perform the movement from. Ever wondered how ballerinas perform multiple turns, finish in awe-inspiring balances and fantastic partner work? The conditioning they have done to their core is the reason they are able to create and sustain this illusion.