One of the reasons we can breathe is because of the elasticity of the lungs. The internal surface of the lungs on average in a non-emphysemic person is normally 63m2 and can hold about 5lts of air volume. Both lungs together have the same amount of surface area as half of a tennis court. Disease such as, emphysema, tuberculosis, can reduce the amount of surface area and elasticity of the lungs. Another big factor in the elasticity of the lungs is smoking because of the residue left behind in the lungs from the smoking. The elasticity of the lungs can be trained to expand further.