Strategies of muscle training in very severe COPD patients

There is strong evidence that exercise training, constituting the cornerstone of pulmonary rehabilitation, improves exercise tolerance, dyspnoea sensations, functional capacity and quality of life in patients with severe chronic obstructive pulmonary disease. However, intolerable sensations of breathlessness and/or peripheral muscle discomfort may prevent such patients from tolerating high-intensity exercise levels for sufficiently long periods of time to obtain true physiological training effects.

Accordingly, the major issue that arises is the selection of the appropriate training strategy, which is tailored to the cardiovascular, pulmonary and peripheral muscle limitations of the individual patient and is aimed at maximising the effect of exercise conditioning.

Within this context, the present article explores the application of strategies that optimise exercise tolerance by reducing dyspnoea sensations, namely noninvasive mechanical ventilation, oxygen and/or heliox supplementation. Administration of heliox or oxygen during exercise also increases peripheral muscle oxygen delivery, thereby delaying the onset of peripheral muscle fatigue. Particular emphasis is also given to interval exercise and resistance-muscle training as both modalities allow the application of intense loads on peripheral muscles with tolerable levels of dyspnoea sensations.

In patients with profound muscle weakness and intense breathlessness upon physical exertion, execution of short bouts of interval or local muscle strength conditioning, along with oxygen breathing, may constitute a feasible and effective approach to pulmonary rehabilitation.

Breathlessness and peripheral muscle discomfort are the most common symptoms limiting exercise tolerance in patients with severe chronic obstructive pulmonary disease (COPD). Exercise training constitutes the cornerstone of pulmonary rehabilitation as there is strong evidence that its implementation improves both exercise tolerance and health-related quality of life in these patients [1]. The intensity of exercise is a key determinant of true physiological training effects: in order to optimise this outcome, it is necessary that the intensity of exercise be as high as possible [2]. Nevertheless, in patients with severe COPD, intolerable sensations of breathlessness and/or peripheral muscle discomfort may prevent high-intensity levels being tolerated for sufficiently long periods of time to yield true physiological training effects [3]. Consequently, it is important to implement strategies to optimise exercise tolerance in severe COPD with the objective of enhancing the patient's ability to tolerate as sustained and intense a workload as possible. These strategies aim at reducing the intensity of dyspnoea sensations, either by allowing patients to sustain a higher absolute exercise-training intensity or by prolonging the cumulative time a given exercise task can ordinarily be sustained. Such strategies include noninvasive mechanical ventilation (NIV), oxygen and/or heliox supplementation and interval cycling modality. In addition, progressive resistance muscle training will be discussed within the scope of reducing leg muscle discomfort.