 Cardiopulmonary exercise testing provides a global assessment of both respiratory lung and cardiovascular heart response to exercise. Whilst studies have shown a worsening of dynamic hyperinflation with bisoprolol, due to their differing pharmacological properties it might be that celiprolol will not result in worsening dynamic hyperinflation, whilst also demonstrating improvement in cardiovascular outcomes such as stroke volume the pump function of the heart and heart rate recovery following exercise. Whether these effects result in an improved exercise tolerance is unknown. Another interesting property of celiprolol is reduced cholesterol and increased High Density Lipoprotein HDL fraction conferred by partial beta-2-agonist activity. We will also measure serum markers of cardiac dysfunction B-type Natriuretic Peptide BNP and Galectin-3 and their response to beta-blockade which to the investigators knowledge has never been performed in a COPD study. 