Air is carried through your lungs from your mouth all the way down to small structures that are like hollow sacs. Each sac contains a mesh of blood vessels where oxygen can enter the bloodstream. When oxygen levels are low, the brain sends signals that say work harder to the muscles that control breathing . This means that people with breathing difficulties due to problems in their respiratory and circulatory have to work harder to get enough oxygen.
Both oxygen and glucose are needed by cells to go through cellular respiration and metabolism which leads to energy.
Playing soccer requires an uptake of oxygen and energy, because of that it would be more difficult for Lucille to play soccer.