3.Explain the change in IC with exercise.

Total Lung Capacity (TLC) is the amount of air in the lungs following a maximal inspiration - maximum chest cavity size. Residual Volume (RV) is the amount of air left in the lungs after maximal expiration - the minimum chest cavity size.

Vital Capacity (VC) is the difference, TLC - RV. In other words, the maximum one can exhale after a maximum inhalation. It depends on chest excursion, or the movement of of the chest cavity, not the actual maximum or minimum size.

Since a person's anatomy does not change before and after an exercise session, the VC will not change in a normal patient between rested and post-exercise tests. A change in VC would point toward some sort of change restricting chest motion- unusual exhaustion, splinting due to pain, muscle injury. An obstruction in air flow such as Exercise Induced Asthma could also cause a lower measured VC, but in an FVC measurement would show a decreased FEV1 / FVC ratio.