Something that happens for who train piano or dance

 And is shake. For the pianist is the fingers because if you make a lot of exercise your body have fat to burn, and trainning the fingers, the fingers is one place of the body that haven't the energy of the fat to keep the energy that you are using to trainning the piano. And for the dancer is the feet, the feet is a place of the body that don't have fat to keep the energy for your training. So when is little the energy the fingers start to shake. Rute Bezerra de menezes Gondim