Problem: When breathing, you're never able to completely fill your lungs with fresh air. A certain volume of stale air always remains in the air passageways. In some lung diseases, such as emphysema, large amounts of stale air accumulate and can't be expelled. The lungs are filled with air that is useless for gas exchange. Vital capacity is significantly less than an in normal lungs. Predict what will happen when a person with emphysema exercises heavily.