Mechanisms and Measures of Exercise Intolerance in Chronic Obstructive Pulmonary Disease
Section snippets
VENTILATORY LIMITATION DURING EXERCISE
A number of processes that affect ventilation interact in the patient with COPD to reduce exercise tolerance and increase breathlessness. Reduced exercise tolerance results from increased ventilatory requirements and reduced ventilatory capacity. Airflow limitation, a hallmark feature of COPD, leads to altered ventilation-perfusion (V/Q) matching in the lung. Loss of elastic recoil also occurs in patients with emphysema. As a result of V/Q mismatching, physiologic deadspace and the ratio of
RESPIRATORY MUSCLE FUNCTION DURING EXERCISE
Although traditionally the most widely accepted explanation for exercise limitation in COPD is decreased ventilatory capacity because of diseased airways and lung-parenchyma, recent attention has also focused on respiratory muscle function. Respiratory muscle strength appears to be an important determinant of exercise tolerance in patients with COPD.4, 58 Data from normal volunteers indicate that the perception of dyspnea during exercise correlates best with the degree of respiratory muscle
CARDIAC LIMITATION DURING EXERCISE
Pathologic studies support the concept that right ventricular hypertrophy and dilatation frequently accompany COPD.85 The role of the cardiovascular system as a cause of exercise limitation in COPD, however, has been thought traditionally to be minimal.13, 22 This view was based on the belief that patients with COPD could not exercise intensely enough to achieve cardiac limitation. Recent work has suggested, however, that the profound respiratory mechanical changes seen in patients with severe
PERIPHERAL MUSCLE WEAKNESS
There is a growing body of evidence supporting a role for peripheral muscle dysfunction as a significant contributing factor to exercise intolerance in patients with COPD.19, 30, 34 This topic is reviewed extensively in the article by Maltais and colleagues elsewhere in this issue. In brief, leg fatigue and discomfort can be the main limiting symptoms during exercise in up to 40% of patients with COPD.34, 53 Peripheral muscle abnormalities in COPD that have been described include reductions in
NUTRITIONAL STATUS AND EXERCISE LIMITATION
Malnutrition, as defined by body weight less than 90% of ideal body weight, has been reported in up to 25% of patients with COPD.91, 92 The importance of this finding is reflected in the well-known increase in mortality rate among malnourished patients with COPD.11 Malnutrition has been demonstrated to affect ventilatory and peripheral muscle strength adversely, thereby reducing exercise tolerance.1 The causes of malnutrition in COPD are not well understood but may include a hypermetabolic
PSYCHOLOGIC VARIABLES IN CHRONIC OBSTRUCTIVE PULMONARY DISEASE
Approximately 45% of patients with COPD describe restrictions in their daily activities, yet physiologic variables may only explain a portion of this disability.68, 79 Psychologic factors such as depression, outlook, and level of self-esteem may also play a role in functional impairment.27 Weaver et al90 evaluated the relationship between physiologic and psychologic variables and functional status in COPD. They examined 104 patients with COPD and measured functional status (Pulmonary Functional
MEASURES OF EXERCISE INTOLERANCE IN CHRONIC OBSTRUCTIVE PULMONARY DISEASE
It is often necessary to quantitate the degree of exercise intolerance experienced by the patient with COPD. Measurement of exercise tolerance can assist in diagnosis of symptoms, enable the assessment of the functional impact of disease progression over time, and identify responses to treatment interventions, such as pulmonary rehabilitation or medication. Exercise tolerance can be assessed by several methods. The choice of method in individual patients depends on equipment availability,
SUMMARY
The mechanisms for exercise intolerance in chronic obstructive pulmonary disease are complex and multifaceted. Although ventilatory limitation caused by abnormal pulmonary function is a major contributor to this phenomenon, other factors may play an important role in limiting exercise. These other factors include depressed cardiac function, respiratory and peripheral muscle weakness, nutritional imbalances, and psychologic factors. The assessment of the pulmonary patient who complains of
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Cited by (44)
Impact of acute exacerbations of COPD on patients' health status beyond pulmonary function: A scoping review
2023, PulmonologyCitation Excerpt :Exacerbations (single or repeated) also result in an acute decrease in functional exercise tolerance, which was expected since the breathing load is acutely increased and patients experience breathlessness even when performing low-intensity activities.47,63 Moreover, fatigue and quadriceps muscle weakness also play a role as limiting factors of exercise performance.64 Surprisingly, although it is often assumed that AECOPD leads to a permanent impairment on exercise performance, it is still unclear if the decrease in exercise tolerance recovers after a few days,24 alongside with symptomatic recovery,6,47,65 or whether it is sustained on a long-term, with studies26,28 even suggesting a sustained impairment 2 years after the exacerbation.
Reproducibility of NIRS assessment of muscle oxidative capacity in smokers with and without COPD
2017, Respiratory Physiology and NeurobiologyCitation Excerpt :Chronic obstructive pulmonary disease (COPD) is characterized by dyspnea on exertion, with subsequent reduced exercise tolerance and quality of life. Skeletal muscle dysfunction is a systemic consequence of COPD that also contributes to increased morbidity and mortality in this population (Agustí et al., 2003; Casaburi, 2001; Decramer et al., 2008; Maltais et al., 2000, 2014; Nici, 2000; Vogiatzis and Zakynthinos, 2012; Wouters, 2002). Morphological and structural skeletal muscle alterations in COPD are especially prevalent in the locomotor muscles, and include atrophy and weakness, loss of type I fibers, loss of muscle oxidative capacity and mitochondrial dysfunction, among others (Allaire et al., 2004; Coronell et al., 2004; Couillard and Prefaut, 2005; Engelen et al., 2000; Gosker et al., 2002, 2007; Maltais et al., 2014; Picard et al., 2008; Whittom et al., 1998).
Simple Lower Limb Functional Tests in Patients with Chronic Obstructive Pulmonary Disease: A Systematic Review
2015, Archives of Physical Medicine and RehabilitationReduced dynamic hyperinflation after LVRS is associated with improved exercise tolerance
2014, Respiratory MedicineDeterminants of exercise capacity in obese and non-obese COPD patients
2014, Respiratory MedicineCitation Excerpt :The six-minute walking test (6MWT) [8] and the incremental cardiopulmonary exercise (CPET) [9] are well accepted tests to evaluate exercise capacity in COPD (10–12). Yet, neither peak oxygen uptake (VO2 peak) determined during CPET [10–12] or the six-minute walking distance (6MWD) can be adequately predicted from the degree of airflow limitation [13–15] as an isolated factor, indicating that factors other than lung function impairment also modulate exercise capacity in COPD. Obesity [16] is often associated with COPD and it has the potential to contribute to exercise limitation [17,18], but its individual contribution to impaired aerobic capacity in these patients is unclear [18–21].
Panic attacks and panic disorder in chronic obstructive pulmonary disease: A cognitive behavioral perspective
2010, Respiratory MedicineCitation Excerpt :Both groups had mean scores in the lower end of the clinical range on measures of anxiety and depression at study entry. Post-intervention, while both groups had improved significantly on the six minute walking test,78 only the CBT group had a significant decrease in anxious and depressive symptoms to below the clinical range. Unlike Emery and colleagues (1998), de Godoy and de Godoy (2003) controlled for attendance of pulmonary rehabilitation, so the decreases in anxiety and depression scores cannot be attributed to physical exercise.76
Address reprint requests to Linda Nici, MD, Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rhode Island Hospital, 593 Eddy Street, Aldrich Building 124, Providence, RI 02903, e-mail: [email protected]
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Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rhode Island Hospital and Brown University, Providence, Rhode Island