Yes. Athletes, and anyone who is going to be completing an action, whether that be sleeping or running a mile, need cellular respiration. Cellular respiration uses glucose and oxygen and results in ATP (the type of energy body's can use). Humans get glucose from the food that they eat. Cellular respiration happens in many cells including muscle cells. Athletes will use more ATP than most, and therefore will need to ingest more glucose to make more energy.
Cellular respiration is the combination of oxygen and glucose in order to produce water, carbon dioxide and energy in the form of adenosine triphosphate (otherwise known as ATP). In this case, glucose is serving as the energy input.
ATP is the form of usable energy by your body. Everyday activities, such as working at a computer requires such energy. However, when you are partaking in more strenuous activities (running, swimming, etc), then your body requires bursts of ATP. Thus, during exercise the rate of cellular respiration increases. (Your respiratory rate and pulse also increase in order to deliver the O2 to the cells and carry away the CO2 that is created during cellular respiration).
The fact that cellular respiration increases during exercise is why it is imperative that athletes increase their caloric intake in order to sustain their activity.