106 / Journal of Cardiopulmonary Rehabilitation and Prevention 2013;33:106-112 www.jcrpjournal.com Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Interstitial lung disease (ILD) is a heterogeneous group of respiratory disorders characterized by lung inflammation and fibrosis that varies in natural clinical course, response to therapy, and prognosis. 1 The mechanisms contributing to exercise limitation arise from a combination of factors including ventilatory, diffusion, and circulatory limitations; gas exchange abnormalities; alterations in respiratory drive; abnor- mal breathing patterns; and peripheral muscle dys- function. 2 ,3 Although limited therapeutic options exist, an emerging body of evidence suggests pulmonary rehabilitation is effective, safe, and feasible in ILD, with studies demonstrating short-term improvements in dyspnea, health-related quality of life, and func- tional exercise capacity. 4 -14 Pulmonary rehabilitation is also recommended in lung transplant candidates to increase fitness for surgery and improve posttrans- plant outcomes, 15 ,16 and ILD is 1 of the major indica- tions for adult lung transplantation. 17 One aim of pulmonary rehabilitation is to increase physical activity. Physical activity has been shown to be reduced early in the disease progression of chronic Lisa Wickerson, MSc, BScPT ; Sunita Mathur , PhD, MSc, BScPT ; Denise Helm, BScPT ; Lianne Singer, MD; Dina Brooks, PhD, MSc, BScPT Physical Activity Profile of Lung Transplant Candidates With Interstitial Lung Disease ■ PURPOSE: Little is known about physical activity in individuals with interstitial lung disease (ILD). The objectives of this study were (1) to objectively measure physical activity in lung transplant candidates with ILD, (2) to compare levels of physical activity on rehabilitation and nonrehabilitation days, and (3) to explore the relationships between physical activity and functional measures. ■ METHODS: Twenty-four (14 men) lung transplant candidates with ILD on long-term oxygen therapy, who were enrolled in an exercise-based rehabilitation program, underwent measurements of physical activity using accelerometry (daily steps and time spent in moderate-intensity physical activity per day), functional exercise capacity (6-minute walk distance), and muscle strength (isometric quadriceps torque). ■ RESULTS: Lung transplant candidates with ILD had reduced levels of physi- cal activity compared to the general population but were more active on rehabilitation versus nonrehabilitation days ( M  SD) (daily steps, 3780  2196 vs 2138  1353; P  .001; and time spent in moderate- intensity activity per day, 4.5 [interquartile range, 1.5-17] minutes vs 2 [interquartile range, 1-3.5] minutes). The 6-minute walk distance showed the strongest correlation to daily steps ( r = 0.59, P  .01) and time spent in moderate-intensity physical activity per day ( r = 0.56, P  .01). ■ CONCLUSIONS: Individuals with advanced ILD are markedly inactive; however, physical activity levels were significantly higher on rehabili- tation days. The importance of physical activity as a rehabilitation out- come in ILD warrants further investigation. K E Y W O R D S interstitial lung disease lung transplantation physical activity Author Affiliations: Toronto Lung Transplant Program, Department of Rehabilitation Sciences, University Health Network (Mss Wickerson and Helm), Department of Physical Therapy, University of Toronto (Ms Wickerson and Drs Mathur and Brooks), and Toronto Lung Transplant Program, University Health Network, and Faculty of Medicine, University of Toronto (Dr Singer), Toronto, Ontario, Canada. The authors declare no conflict of interest. Correspondence: Lisa Wickerson, MSc, BScPT, Toronto Lung Transplant Program, Department of Rehabilitation Sciences, University Health Network, 200 Elizabeth St, Toronto, ON M5G 2C4, Canada (lisa.wickerson@uhn.ca). DOI: 10.1097/HCR.0b013e3182839293