Exercise training, along with smoking cessation, are key components for treating COPD and are an important piece of pulmonary rehabilitation.
Chronic Obstructive Pulmonary Disease (COPD) is the third leading cause of death in the United States. COPD is associated with chronic, progressive lung airflow limitation in response to noxious particles. In the US, 80-90% of COPD patients are smokers, but worldwide biomass fuel pollution is the most common etiology. In addition, a genetic defect in the protease inhibitor alpha-1 antitrypsin is responsible for 1-3% of cases of COPD.
Regardless of the trigger, COPD is caused by an uncontrolled or hyperactive immune response, which leads to emphysema and/or chronic bronchitis. COPD is defined by trouble with expiration, which leads to air trapping in lung alveoli and the classic presentation of a "barrel chest” in COPD patients. Although men previously had a higher incidence of COPD, today women have a higher COPD incidence and mortality rate than their male counterparts as a result of increased smoking rates among women. COPD patients generally feel short of breath (dyspnea) and this is exacerbated upon exertion.
There are several evidence-based guidelines for treating COPD to reduce morbidity and mortality. Smoking cessation is paramount and can lead to a dramatic halt in the progression of the disease. Along with smoking cessation, oxygen therapy, bronchodilators and surgery (lobectomy) are other proven measures of reducing COPD mortality. Pulmonary rehabilitation and vaccination are other measures proven to reduce COPD morbidity.
COPD Exercise-Dyspnea Spiral
Exercise training is the most important component of pulmonary rehabilitation for COPD patients. One of the problems that COPD patients have is that exercise is very difficult. COPD patients are generally short of breath at rest, and exercise augments their hypoxia (oxygen deficiency). This leads to a downward spiral whereby COPD patients to become progressively more sedentary, exacerbating their muscle wasting, leading to more difficulty with exercise and further inactiveness. Pulmonary rehabilitation teaches patients several strategies for exercising for short bouts with COPD. These strategies include a quick inhalation followed by a prolonged pursed lip exhalation. Pursing the lips during exhalation maintains a positive pressure in the lungs keeping the airways open.
Why is exercise so important? First, it helps COPD patients maintain a respiratory reserve at rest. This is critical for surviving an acute exacerbation, such as a pneumonia, which reduces respiratory capacity. Second, it can prevent crippling muscle loss during an exacerbation (Resistance Training Prevents Deterioration in Quadriceps Muscle Function During Acute Exacerbations of Chronic Obstructive Pulmonary Disease, 2010. Troosters, et al.). Studies have shown no difference between endurance training and resistance training in their ability to improve the quality of life of rehabilitation participants for COPD (A Systematic Review of Resistance Training Versus Endurance Training in COPD, 2015. Jepsen UW, et al.). Ideally, a pulmonary rehabilitation program for COPD should run at least eight weeks.