Adaptation for speed is further exhibited in the moulding of the shape of the body so as to present the minimum amount of resistance to the air, as well as in increase in heart and lung capacity to meet the extra expenditure of energy.
These tests are also done before major lung surgery to make sure the patient will not be disabled by having a reduced lung capacity.
Total lung capacity is measured by body plethysmography.
During the test, the child exhales and the spirometer measures the airflow, comparing lung capacity to the normal range for the child's age and race.
The child then inhales a drug that widens the air passages (a short-acting bronchodilator) and the doctor takes another measurement of the lung capacity.