Due to Emphysema the pressure in the lungs (and on the blood vessels and airways respectively.) rises. This creates the basis for the development of further diseases (e.g. overstress of the heart, pulmonary hypertension).

Furthermore, the diaphragm is pushed downward: This leads to phrenoptosis, a flattened diaphragm. Thus, the most important respiratory muscle is not able to move down any further and (thus) is not able to draw in more air. This deficiency is redistributed: the accessory muscles of respiration need to work proportionally harder and eventually become over stressed overtime.

Did you know?
Altogether, the breathing depth (How much air is moved by a breath?) on exertion is not as deep as in a person with a healthy lung. Usually, it is only possible to breath faster, the amount of air on exertion decreases [dynamic hyperinflation = pump up yourself]. This additionally diminishes exercise capacity.