Activity restriction in mild COPD: a challenging clinical problem

Abstract

Dyspnea, exercise intolerance, and activity restriction are already apparent in mild chronic obstructive pulmonary disease (COPD). However, patients may not seek medical help until their symptoms become troublesome and persistent and significant respiratory impairment is already present; as a consequence, further sustained physical inactivity may contribute to disease progression. Ventilatory and gas exchange impairment, cardiac dysfunction, and skeletal muscle dysfunction are present to a variable degree in patients with mild COPD, and collectively may contribute to exercise intolerance. As such, there is increasing interest in evaluating exercise tolerance and physical activity in symptomatic patients with COPD who have mild airway obstruction, as defined by spirometry. Simple questionnaires, eg, the modified British Medical Research Council dyspnea scale and the COPD Assessment Test, or exercise tests, eg, the 6-minute or incremental and endurance exercise tests can be used to assess exercise performance and functional status. Pedometers and accelerometers are used to evaluate physical activity, and endurance tests (cycle or treadmill) using constant work rate protocols are used to assess the effects of interventions such as pulmonary rehabilitation. In addition, alternative outcome measurements, such as tests of small airway dysfunction and laboratory-based exercise tests, are used to measure the extent of physiological impairment in individuals with persistent dyspnea. This review describes the mechanisms of exercise limitation in patients with mild COPD and the interventions that can potentially improve exercise tolerance. Also discussed are the benefits of pulmonary rehabilitation and the potential role of pharmacologic treatment in symptomatic patients with mild COPD.

The importance of physical activity

“…Deconditioning and muscle weakness are physiological consequences of inactivity that can also be observed in healthy subjects within 2 weeks of reduced physical activity [17]. These data suggest that reductions in physical activity will lead to deconditioning, worsening of dyspnoea and a further reduction in physical activity levels [12,15]. This brings patients into a vicious cycle of inactivity that is difficult to reverse [15].…”

“…The potential mechanisms explaining the presence of (early) physical inactivity and worsening throughout the course of the disease are illustrated in figure 1. Abnormalities in pulmonary function and gas exchange (leading to higher ventilatory requirements during exercise), as well as skeletal muscle dysfunction are already present to a variable degree in early disease stages and can contribute to the perception of increased exertional dyspnoea and leg fatigue [11,15,16]. These symptoms make exercise an unpleasant experience and patients probably adapt to this by decreasing their physical activity, most likely beginning with nonessential leisure activities followed by activities of daily living.…”

“…These symptoms make exercise an unpleasant experience and patients probably adapt to this by decreasing their physical activity, most likely beginning with nonessential leisure activities followed by activities of daily living. This results in an inactive lifestyle, which is likely to aggravate exercise limitation [12,15]. Deconditioning and muscle weakness are physiological consequences of inactivity that can also be observed in healthy subjects within 2 weeks of reduced physical activity [17].…”

Gender disparity of changes in heart rate during the six-minute walk test among patients with chronic obstructive airway disease

“…2 COPD is clinically characterized by a pathological rate of decline in lung function with age, and, as a result, patients with COPD often complain of dyspnea and exercise intolerance, both of which not only interfere with the ability to perform the activities of daily life but also significantly impede quality of life. 2,3 COPD patients have limited exercise capacity due to complex pathophysiology, and evaluation of exercise performance at all stages of COPD is important if we are to understand disease progression better 4 . However, there has been limited development of maximal incremental load exercise test specific for heart rate parameters in patients with COPD.…”

“…The 6-minute walk test (6MWT) has classically been used in clinical settings to evaluate exercise capacity at submaximal exercise levels and to assess the effects of treatment in individuals with a variety of cardiovascular and pulmonary diseases, including COPD. 4,5 The test is easy to administer, better tolerated than some other tests, and its reflective of physical activities. 6 The 6-minute walk distance (6MWD) has been widely applied as a representative parameter in the 6MWT, in patients with COPD.…”