A healthy person at rest takes in and expels about 500 ml of air in one respiratory cycle. This is called the tidal volume. If one takes in a very deep breath, it is possible to inhale 3 liters of air over and above the tidal volume. This is called the inspiratory reserve volume. After the end of a normal expiration, it is possible to exhale an extra 1 liter of air. This is called the expiratory reserve volume.
The total amount of air that can be exhaled after taking the deepest possible breath is called the vital capacity. In an average healthy adult the vital capacity is about 4.5 liters. Athletes have a much higher vital capacity which may exceed 6 liters. After a maximum expiration, about one and half liters of air remains in the lungs. This is called the residual volume that endures the athletes on tracks.