There are many different systems involved in when we exercise, the three main ones are the Respiratory system which is involved in breathing the circulatory system which is about circulation of blood around the body and finally the muscular system and finally the Muscular system which is about how we move.
Not sure if this is an open-ended,or multiple choice. Either way,I think they'd do it to ensure a victory, and to keep the teams motivation up. If I get this wrong,I take responsibility for it. Hope this helps! ^-^