COPD is a chronic and progressive lung disease that encompasses two main conditions- emphysema and chronic bronchitis.
Emphysema is characterized by the destruction of the lung parenchyma, which is just a fancy word for the functional part of the tissue, so this would be the single-cell layers in the alveoli.
This destruction results in the enlargement of the alveolar space and reduces the surface area for gas exchange. If you recall any human physiology or biology that you might have had previously when we open up the lung and spread it out as a single layer it is essentially the size of a tennis court. The ability to move oxygen from the lung to the capillaries is directly proportional to the amount of surface area in the lungs, so the destruction of the alveoli significantly reduces the ability to get oxygen into the blood.
Bronchitis is more of an inflammatory response causing swelling and a narrowing of the airway.
As COPD is a progressive and chronic disease it is often managed with pharmacological interventions.
The following medications are the most commonly used and while they are quite useful for symptom management, they can also have an effect on exercise responses.
Beta-agonist bronchodilators are administered to help alleviate some of the expiratory flow limitations, however, they do not completely abolish it in COPD. While they provide relief for respiration they have the effect of increasing resting heart rate and altering the heart rate response to exercise. Thus care should be taken when prescribing exercise based on heart rate responses in COPD patients as typical responses may not be observed.
Corticosteroids are often utilized to minimize the inflammatory responses to COPD. These may cause muscle weakness and fragility and over the longer term may contribute to osteoporosis. Again care must be taken when prescribing resistance training exercises in this group of patients.
While we must be aware of the exercise-drug interactions, it is also clear that exercise can serve as a tool to support improvements in the side effects of these medications.