Physical activity in patients with idiopathic pulmonary fibrosis

Physical activity is an important parameter in patients with chronic obstructive pulmonary disease, but has not been studied in detail in patients with interstitial lung disease. This study aimed to evaluate physical activity in patients with idiopathic pulmonary fibrosis (IPF).

Physical activity was monitored in 31 stable IPF patients using an accelerometer for 1 month. The following factors reflecting physical activity were measured: the number of steps, walking distance, the time spent at magnitude of movement (MM) 1-6, physical activity-related energy expenditure (PAEE) and total energy expenditure. We also measured the following clinical parameters: the modified Medical Research Council (MRC) scale, Krebs von den Lungen-6 (KL-6), pulmonary function parameters, 6-min walk test (6MWT) results and high-resolution computed tomography (HRCT) findings of the chest. We determined the relationship between these parameters and physical activity.

We recorded 24 days of physical activity data. The time spent at MM < 1 was more than 10 h per day, whereas that at MM > 1 was approximately 1 h per day. The modified MRC scale, serum KL-6 levels, 6MWT distance, and the extent of honeycomb and reticular abnormality on HRCT were associated with several facets of physical activity. In particular, lower KL-6 levels were correlated with higher physical activity based on the number of steps, walking distance, the time spent at MM 1-4 and PAEE.

The modified MRC scale, 6MWT distance, extent of fibrosis on HRCT and serum KL-6 levels are strongly associated with physical activity.