There are many ways in which cancer can cause fatigue. The growth of a tumor, in general, can be taxing for your body. Other symptoms of cancer such as shortness of breath, anemia, pain, or a decreased level of oxygen in your blood (hypoxia) can cause fatigue.
A pulmonary function test may take 30 to 60 minutes to complete. This will vary according to the amount of trials necessary for you to get repeatable test results.
Participants had a sustained improvement in exercise capacity at 6 months into their extended pulmonary rehabilitation exercise programs. However, at 12 months, there were no significant differences between groups in pooled data from 5 of the trials.