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Pulmonary Medicine
Volume 2013, Article ID 956081, 13 pages
Review Article

Inspiratory Capacity during Exercise: Measurement, Analysis, and Interpretation

1Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada V6T 1Z3
2UBC James Hogg Research Centre, Institute for Heart + Lung Health, St. Paul’s Hospital, Vancouver, BC, Canada V6Z 1Y6
3Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston General Hospital, Kingston, ON, Canada K7L 2V7

Received 20 July 2012; Accepted 21 December 2012

Academic Editor: Jose Alberto Neder

Copyright © 2013 Jordan A. Guenette et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Cardiopulmonary exercise testing (CPET) is an established method for evaluating dyspnea and ventilatory abnormalities. Ventilatory reserve is typically assessed as the ratio of peak exercise ventilation to maximal voluntary ventilation. Unfortunately, this crude assessment provides limited data on the factors that limit the normal ventilatory response to exercise. Additional measurements can provide a more comprehensive evaluation of respiratory mechanical constraints during CPET (e.g., expiratory flow limitation and operating lung volumes). These measurements are directly dependent on an accurate assessment of inspiratory capacity (IC) throughout rest and exercise. Despite the valuable insight that the IC provides, there are no established recommendations on how to perform the maneuver during exercise and how to analyze and interpret the data. Accordingly, the purpose of this manuscript is to comprehensively examine a number of methodological issues related to the measurement, analysis, and interpretation of the IC. We will also briefly discuss IC responses to exercise in health and disease and will consider how various therapeutic interventions influence the IC, particularly in patients with chronic obstructive pulmonary disease. Our main conclusion is that IC measurements are both reproducible and responsive to therapy and provide important information on the mechanisms of dyspnea and exercise limitation during CPET.