This study will determine if airway resistance to airflow and pressure, measured by Oscillometry, is associated with abnormal findings on Cardiopulmonary Exercise Testing in subjects who are experiencing shortness of breath.

Inclusion Criteria:

• Willingness to perform breathing test
• Must be able to speak and understand English
• Referred for Cardiopulmonary Exercise Testing

Exclusion Criteria:

• Unable to provide consent or perform oscillometry test

Up to fifty (50) human subjects will be recruited from the following University of Rochester locations: Mary Parkes Center for Asthma, Allergy, and Pulmonary Care, the Pulmonary Clinic at Strong Memorial Hospital, and The Pulmonary Clinic at Highland Hospital.