Exercise Training in Severe COPD

Rehabilitation in-hospital program The rehabilitation program (RP) will start the day after the in-hospital admission and will be continuously supervised by a physiotherapist. The patients will use the drugs and the oxygen therapy prescribed. RP will include a training session on cycloergometer at constant load once a day (Group F1) or twice-a day (Group F2) interrupted by at least three hours of rest. The workout will start with a workload of 50% of the theoretical maximum Watts indirectly assessed by the 6-Minutes Walking Test (6MWT) with equation of Luxton et al. Measures At baseline (T0) we will gather in both groups the following evaluations: 1. Anthropometric parameters (age, BMI) 2. Scale of comorbidity CIRS At the baseline (T0) and end of the program (T1) we will collect, in all patients, the following evaluations: 1. 6-minute walking test walk (6MWT) will be performed according to international guidelines. In patients using oxygen during walking, the oxygen flow will be adjusted to increase the oxygen saturation over 96%.The 6MWT at T1 will be performed with the same amount of oxygen used in the initial test (T0). 2. Endurance cycloergometer test will be performed at 80% of Watts max predicted by the 6MWT. At the beginning, the test will be performed at charge "zero watts" for 2 minutes, then the workload will be increased to 80% of the theoretical max Watts until muscle exhaustion (Borg score \> 8), presence of high dyspnea (Borg score \> 8) or the achievement of 90% of theoretical maximal heart rate. The final endurance test will be repeated at the same load (speed 50-60 rpm). The time spent for performing the exercise will be registered. In a subset of patients (belonging to the Institute of Lumezzane) the endurance cycloergometer test on the quadriceps muscle will be executed by the Near Infrared Spectroscopy (NIRS ). 3. Scale of the MRC dyspnea 4. Arterial blood gas analysis 5. Respiratory muscle strength (Maximal lnspiratory Pressure \[MIP\] and Maximal Espiratory Pressure \[MEP\]) 6. Biceps and quadriceps muscle strength evaluated with dynamometer manual 7. CAT scale Only at the end of the program (T1) we will collect: 1. patient satisfaction by a Likert scale taking into consideration the quantity, quality, and impact of rehabilitation on hospitalization 2. The time consuming for the two programs 3. The side effect 4. The drop out (waste, flare)