Phase IV O2 Consumption Study in COPD Patients.

Subjects will receive a single dose (2 inhalations) of Symbicort pMDI 160/4.5 μg (2 inhalations; total dosage 320/9.0 μg) or placebo (with a spacer) in a cross-over design (a total of 2 doses of Symbicort and 2 doses of placebo over the duration of the study), and assessments will be made before and after dosing at specified timepoints

Placebo will be given according at the same dose and schedule as the active comparator - cross-over design.