Chronic Obstructive Pulmonary Disease (Copd)
Chronic obstructive pulmonary disease (COPD) is a disease characterized by the presence of airflow obstruction that is attributable to either chronic bronchitis or emphysema (1, 2). Chronic bronchitis is a clinical diagnosis for patients who have chronic cough and sputum production. It is formally defined by the American Thoracic Society as the presence of a productive cough most days during three consecutive months in each of two successive years (1, 6). The cough is a result of hyper-secretion of mucus, which in turn is the result of an enlargement of the mucus-secreting glands. In contrast to the clinical diagnosis for chronic bronchitis, emphysema is a pathological or anatomical diagnosis marked by abnormal permanent enlargement of the respiratory bronchioles and the alveoli, that is, the airspaces distal to the terminal bronchioles. It is accompanied by destruction of the lung parenchyma without obvious fibrosis (6, 7). Most patients with COPD have both chronic bronchitis and emphysema with the relative extent of each varying among patients. The underlying pathology therefore differs but the symptoms are the same, that is, shortness of breath on minimal exertion because lung function is impaired. Most patients are elderly and ex- or current smokers. The development of COPD is silent and insidious because the healthy lung has good reserves of gas capability. This reserve of function is eaten away by disease without any noticeable effects until, when approximately 60% of airway function is lost, symptoms develop.
Copd and Exercise
The evidence for the therapeutic value of exercise is strong and extensive for COPD. The disease is progressive and unlikely to undergo spontaneous natural remission. Once optimal medical treatment has been effected, rehabilitation focuses on the reduction of disability.
Rehabilitation is a relatively new feature of the management of patients with COPD, having been introduced in the US only in the 1980s (even later in Europe) when it was realized how much physical deconditioning and emotional responses to disability contributed to the resulting morbidity. Three features are common to most programmes, that is, exercise, disease education and psychosocial support. The exercise component is usually brisk walking or, less commonly, cycling. Training of the muscles of the upper extremities is sometimes included because this will diminish the ventilatory requirement of tasks using the arms.
What does pulmonary rehabilitation achieve? There is ample evidence that this cannot alter parameters that reflect impairment, for example, FEV1, blood gases or even maximal exercise capacity. Outcome measures are focused on assessment of disability, such as walking performance, health status. These aim to reflect any changes in symptoms, improvements in function and independence in daily life (3).
In one large trial, 200 patients were randomized to a 6-week rehabilitation programme (education, including smoking cessation, recognizing and dealing with symptoms; aerobic exercise for arms and legs; and psychological issues relating to chronic disability) (4). Patients in the rehabilitation group were encouraged to exercise at home after the out-patient programme and all patients were followed for 1 year. Rehabilitation improved walking performance; after 6 weeks, patients in the rehabilitation group walked both faster and 50% further than controls in a symptom-limited ‘shuttle’ walking test. Rehabilitation also reduced breathlessness and fatigue, improved patient’s sense of control over their disease and improved their perception of their general health status. Some benefits were still evident 1 year later. During this year, patients in the rehabilitation group used fewer National Health Service resources: they spent only half as many days in hospital as those in the control group, required fewer home visits from their general practitioner and less medication.
This study is not atypical. A review from the Cochrane Collaboration, based on 23 randomly controlled trials, concluded that rehabilitation for COPD results in moderately large and statistically significant improvements in health status (dyspnoea, fatigue, mastery) above the minimum clinically important difference and small improvements in walking distance (5).
What mechanisms are responsible for these improvements? The answer to this question is unclear. Training does not seem to lead to major adaptations of skeletal muscle metabolism in these patients, as it does in healthy people. One explanation is that patients cannot attain an intensity of exercise sufficient to stimulate these adaptations. The decrease in dyspnoea has been variously attributed to desensitization, (learning to overcome the anxiety associated with dyspnoea) or maybe to improved mechanical skill.
If you have COPD, learn about how COPD is a chronic disease which is eligible to receive a Medicare Rebate when seeing an Accredited Exercise Physiologist:
Did you know you could get up to 50% off with a Medicare Rebate?
Learn how an Accredited Exercise Physiologist can help you to begin and maintain exercise in your life, so you can enjoy the health benefits of Exercise for COPD:
What Does an Exercise Physiologist Do?