Patients admitted with AECOPD will be recruited for the study. AECOPD will be defined when a patient with background COPD has at least two of the major symptoms (increased dyspnoea, increased sputum purulence, increased sputum amount) or one major and one minor symptom (nasal discharge/congestion, wheeze, sore throat, cough) for at least two consecutive days.5,17 Inclusion criteria include patients who are ambulatory (no major joint problem and no Class III or IV angina), patients agree to join exercise programme if offered, the forced expiratory volume in 1 second (FEV1) <70% predicted normal and an age of over 40 years old. Patients who have had PRP within the past 1 year will not be recruited for this study.