Exercise capacity and physical activity in patients with COPD and healthy subjects classified as medical research council dyspnea scale grade 2

摘要

PURPOSE: Patients with chronic obstructive pulmonary disease (COPD) are often classified by Medical Research Council (MRC) dyspnea grade and comparisons thus made to healthy individuals. The MRC grade of a healthy population is assumed to be grade 1, although this may be inaccurate. Physical activity and exercise capacity are not well-defined for those with MRC grade 2. This study was undertaken to establish whether there are differences in physical activity and exercise capacity between individuals with COPD and healthy controls, who have all assessed themselves as MRC grade 2. METHODS: Patients with COPD (n = 83) and 19 healthy controls, with a self-selected MRC grade of 2, completed the Incremental Shuttle Walk Test (ISWT) and wore a SenseWear (BodyMedia, Pittsburgh, PA) activity monitor for 12 hours for 2 weekdays. RESULTS: Adjusting for age, step count and ISWT were significantly reduced for those with COPD, compared with healthy controls (P < .05). Patients with COPD achieved mean (SD) 425.5 (131.3) m on ISWT and took 6022 (3276) steps per day compared with 647.8 (146.3) m and 9462 (4141) steps per day for healthy controls. For subjects achieving 10 000 steps per day, 8 (42.11%) healthy controls achieved this level compared with 7 (8.43%) patients with COPD (P < .01). CONCLUSIONS: Healthy individuals may report functional limitations and categorize themselves as MRC grade 2. However, despite both groups subjectively considering themselves similarly functionally limited, exercise capacity and physical activity were significantly reduced in patients with COPD compared with healthy participants. This highlights the importance of early interventions to increase physical performance and prevent functional decline for patients with COPD.