History of major trauma and/or major orthopedic surgery of the spine, the pelvis or the lower quadrant

One of the following conditions: Parkinson, multiple sclerosis, stroke, history of vestibular disorder

Respiratory disorder other than COPD

α1-antitrypsin deficiency

Known history of significant inflammatory disease other than COPD

COPD exacerbation within 4 weeks prior to study

Lung surgery

Recent diagnosis of cancer

Therapy with oral corticosteroids in the last 6 weeks

Significant cardiovascular comorbidity

Proprioceptive Postural Control and Chronic Obstructive Pulmonary Disease (COPD)