Evaluation of a Simple Clinical Test to Detect the Risk of Falling in Patients With BPCO and Research for Predictive Factors of Fall Risk.

We will recruit COPD patients in stable condition (free of exacerbation of the disease for a month), 40 without chronic respiratory failure and 40 with home oxygen therapy. The patients will be proposed to perform the following tests and to fill in questionnaires: \- Questionnaires: Elderly Falls Screening Test to quantify the falls in the last year, Hospital Anxiety and Depression Scale, Activities-specific Balance Confidence scale. Tests: * Berg Balance Scale measuring balance in 14 different functional tasks (abnormal cut-off value \<56) * Timed Up and Go evaluating the time to rise from a chair, walk 3 meters, turn around, walk back to the chair and sit down (abnormal cut-off value \>12 seconds). * 6 minute walk test evaluating endurance to submaximal exercise. * Isokinetic maximal force of the quadriceps at 60°/s * Balance control: posturography consisting in measuring variations when standing on a force platform. * Body composition assessment through Dual Xray Absorptiometry (DXA), to measure body muscle mass and more specifically appendicular muscle mass index as a criteria of sarcopenia, and bone mineral density. * Blood analysis: a blood sample will be withdrawn to measure calcium, phosphorus, vitamin D, albumin transthyretin, cell count, C reactive protein. Analysis of the results: We will calculate the sensitivity of the TUG test (abnormal test) to detect fall risk as assessed by an abnormal BBS score. Moreover, in fallers, we will search for predictive factors. More specifically, we will look for the role of a decreased quadriceps force, a reduced muscle mass, a poor tolerance of exercise, the presence of hypoxia (severity of the disease). Perspectives: When validated as a screening test for the risk of falling in COPD patients, the TUG test could be used routinely by physiotherapists as a more simple and faster test and will enable to prevent falls through initiation of a balance control training program.