The purpose of this study is to investigate how budesonide/formoterol fumarate dihydrate (Symbicort ©) affects dynamic hyperinflation in patients with obstructive disease using Optoelectronic Plethysmography (OEP). This study is unique as it will be the first randomized, doubleblind, crossover study with a placebo inhaler and budesonide/formoterol fumarate dihydrate as the intervention which will evaluate the effects on ventilatory mechanics through the use of OEP. The investigators plan to demonstrate that budesonide/formoterol fumarate dihydrate impacts dynamic hyperinflation which can be detected with OEP, and that budesonide/formoterol fumarate dihydrate may have an effect in the short term on exercise capacity during a constant load exercise test. The changes in ventilatory mechanics measured after budesonide/formoterol fumarate dihydrate by OEP will provide a unique evaluation of budesonide/formoterol fumarate dihydrate in a controlled setting also demonstrating the utility of OEP in evaluating of the effects of a medical treatment on hyperinflation in individuals with chronic obstructive lung disease (COPD).