Clinical exercise testing in interstitial lung disease.

Clinical exercise testing has become an essential tool used in the early diagnosis, in the monitoring of treatment effectiveness, and in the assessment of impairment owing to ILD. Despite the assorted causes, the responses to exercise demonstrated by these diseases are generally similar. Although much has been learned about how these diverse diseases functionally impair the exercise capacity of the patient, further study is required if we are to understand fully the various physiologic abnormalities manifested by patients with ILD during exercise.