TY - JOUR T1 - Chicken or egg: physical activity in COPD revisited JF - European Respiratory Journal JO - Eur Respir J SP - 227 LP - 229 DO - 10.1183/09031936.00176808 VL - 33 IS - 2 AU - M. I. Polkey AU - K. F. Rabe Y1 - 2009/02/01 UR - http://erj.ersjournals.com/content/33/2/227.abstract N2 - Quietly, over recent years, a reassessment has occurred amongst those caring for patients with chronic obstructive pulmonary disease (COPD). Although COPD is triggered by the inhalation of noxious stimuli, usually cigarette smoke, it is now apparent that the condition has a significant extrapulmonary component 1. COPD is of course diagnosed by the finding of a reduced forced expiratory volume in one second (FEV1); however, amongst patients with an FEV1 of <50% predicted, FEV1 is a poor predictor of survival. What then does predict survival amongst patients with advanced disease? Certainly weakness of the principle locomotor muscle, the quadriceps, does 2, as does the reduction in quadriceps cross-sectional area 3. It is also well established that exercise capacity, whether measured on a field test, as in the BODE (body mass index, airflow obstruction, dyspnoea, exercise capacity) score 4, or in the laboratory 5, is predictive of survival. Lastly, in large cohorts it is clear that self-reported physical activity predicts prognosis in COPD 6 and may even impact on the rate of lung function decline 7. Indeed, recent data from 77,000 participants in the Nurses Health Study suggests that a lack of physical exercise is a major contributor to all causes of mortality irrespective of smoking history, although the latter is of course a separate and major risk factor 8. Daily physical activity, muscle strength and performance are likely intimately interlinked; progress in the former area has been greatly advanced by the development of technology which permits physical activity monitoring. In its earliest guise, this could be as simple as a pedometer 9 or an actigraph 10. However, most investigators prefer the more sophisticated devices now … ER -