Cellular respiration is the process in which your muscles<span> use </span>oxygen<span> to produce ATP energy. The process is simple. Your body obtains </span>oxygen<span> from the ambient air you breathe. ... Whether you're </span>exercising<span> or not, the </span>oxygen<span> in your body is used to break down glucose and create the fuel for your </span>muscles<span> called ATP.</span>
