Student athletes accustomed to exercise do generally have greater lung capacity than unathletic students with equal body or lung size, according to an article in the European Journal of Applied Physiology. However, lung capacity is also a result of other factors more relevant than athleticism.
Lung capacity refers to the amount of air a person is able to hold in his lungs. Doctors measure it in several different ways. The easiest is to measure the maximum volume of air that a person is able to exhale in one breath. Athleticism helps only if it provides stronger control of the muscles used in breathing.
This volume is largely a result of the size of each person's lungs. Taller and larger, non-obese people are both likely to have larger lungs and to be able to hold more air. Location also matters, according to Wikipedia; people who live at sea level have less lung volume than people who live at high altitudes.