Running has a number of body systems constantly working together. Systems like; the nervous, skeletal, muscular, respiratory, and the circulartory system.
When we run, a signal is sent from the brain to the nervous system, causing our muscles to contract and we start to run. The process of running uses a lot of energy and this energy is provided to us by cellular respiration.
We use the respiratory system to deliver oxygen to the body, where it interacts with food and generates energy. The carbon dioxide produced is removed by the respiratory system.