Physical activity and exercise capacity in patients with moderate COPD exacerbations

Introduction: Little is known about changes in physical activity during moderate (out-patient managed) exacerbations. Methods: Six minute walking distance (6MWD) was measured during 50 exacerbations when the patients were stable, and at 3 and 7 days post exacerbation presentation. At similar time points, quadriceps maximum voluntary contraction (QMVC) was measured during 47 different exacerbations. Physical activity (SenseWear) was recorded over two consecutive week periods post presentation. Results: 6MWD fell from a median 422 metres when stable to 373 metres on day 3 (p=0.001). Similarly, QMVC fell from 32.6 vs. 29.7 kg (p=0.026). Falls in 6MWD were associated with rise in C-Reactive Protein (r=-0.364; p=0.041) and increased FACIT fatigue (r=-0.44; p=0.013). Light physical activity was 2.18 hours/day during the first week post exacerbation and was less over week 2, 1.98 hours/day (p=0.009). Patients who had attended pulmonary rehabilitation (PR) had smaller changes in 6MWD than those who had not attended (-35.0 vs. -114.9 meters; p=0.013). Falls in physical activity were correlated with higher depression scores (rho=-0.51; p=0.006). Conclusion: These findings indicate that exercise capacity and muscle strength falls at exacerbation in COPD patients treated at home and free to maintain normal activity