The MPT test shows good overall accuracy to identify subjects who are susceptible to develop dynamic hyperinflation during CPET. Before considering the use of MPT as a screening tool for dynamic hyperinflation in COPD, sensitivity and specificity need further evaluation.

In patients with chronic obstructive pulmonary disease (COPD), exercise capacity is reduced, resulting over time in physical inactivity and worsened health status. It is unknown whether ventilatory constraints occur during activities of daily life (ADL) in early stages of COPD. The aim of this study was to assess respiratory mechanics during ADL and to study its consequences on dyspnoea, physical activity and health status in early-stage COPD compared with healthy controls. In this cross-sectional study, 39 early-stage COPD patients (mean FEV1 88±s.d. 12% predicted) and 20 controls performed 3 ADL: climbing stairs, vacuum cleaning and displacing groceries in a cupboard. Respiratory mechanics were measured during ADL. Physical activity was measured with accelerometry. Health status was assessed by the Nijmegen Clinical Screening Instrument. Compared with controls, COPD patients had greater ventilatory inefficiency and higher ventilatory requirements during ADL (P<0.05). Dyspnoea scores were increased in COPD compared with controls (P<0.001). During ADL, >50% of the patients developed dynamic hyperinflation in contrast to 10–35% of the controls. Higher dyspnoea was scored by patients with dynamic hyperinflation. Physical activity was low but comparable between both groups. From the patients, 55–84% experienced mild-to-severe problems in health status compared with 5–25% of the controls. Significant ventilatory constraints already occur in early-stage COPD patients during common ADL and result in increased dyspnoea. Physical activity level is not yet reduced, but many patients already experience limitations in health status. These findings reinforce the importance of early diagnosis of COPD and assessment of more than just spirometry.

Chronic obstructive pulmonary disease (COPD) is one of the leading causes of disability and death worldwide. Although COPD is considered to be a preventable and treatable disease, there are concerns that COPD remains substantially underdiagnosed and undertreated. Even in mild disease, patients suffer from significant impairments in health status, which places a considerable burden on patients as well as society. Symptomatic patients are likely to progress to more advanced disease. To avoid breathlessness, they adapt and gradually reduce their activities, which, inevitably, leads to further deconditioning. As a consequence, a progressive deterioration in physical activity with increasing severity of COPD can be observed. Because physical activity is closely related to exacerbation rate, hospitalization, and mortality in patients with COPD, it is important to recognize the role of pharmaceutical interventions in enabling patients to stay physically active. Bronch(iol)odilation not only has important direct effects (symptom relief), but also exerts indirect effects on exercise capacity, exacerbation rate, health status, and mortality. In patients with COPD, the latter effects may be even more important than the direct effects. In this review the current view on causes and consequences of activity limitation in COPD is summarized. From this perspective, the rationale behind bronch(iol)odilator therapy as the cornerstone of treatment for patients with COPD will be discussed.

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