What are the important components of physical activity for people with fibrotic interstitial lung disease?

IntroductionFibrotic interstitial lung disease (fILD) is characterized by scarring of the lungs, decline in lung function and compromised exercise capacity. People with fILD participate in less daily physical activity compared to healthy controls, however, the relative importance of physical activity components (volume, intensity, duration) is unknown. This study aimed to examine the relationship between the components of physical activity and established disease severity and impact measures in fILD.MethodsParticipant data were from baseline assessment of a randomized controlled trial recruiting people with fILD and exertional desaturation during exercise testing on room air. Physical activity components including volume (steps per day), intensity (light, moderate and vigorous) and duration (time spent in different physical activity intensities) were objectively assessed for 7 days using two physical activity monitors. Associations of these components with lung function (FVC, FEV1, TLCO), functional exercise capacity (6-min walk distance, 6MWD) and dyspnea (Dyspnea-12 questionnaire) were investigated.Results106 participants with mild to severe fILD were included. Physical activity volume was not associated with 6MWD (r = 0.027, p = 0.78) and weakly associated with lung function (FVC r = 0.33, p = 0.001; FEV1 r = 0.34, p = 0.001). Physical activity intensity and duration were weakly associated with 6MWD (light r = 0.22 p = 0.02; moderate r = 0.42, p < 0.001; vigorous r = 0.33, p = 0.01). Time spent in vigorous physical activity was weakly associated with lung function (FVC r = 0.19, p = 0.05; FEV1 r = 0.18, p = 0.006). Dyspnea scores were not associated with any physical activity variables. Relationships remained consistent after adjusting for age, gender and disease severity, with the exception of vigorous physical activity which was no longer associated with lung function or 6MWD.ConclusionIn people with fILD, the physical activity components of volume, intensity and duration were associated with different measures of disease severity and impact. This highlights the importance of considering specific physical activity components when evaluating and promoting physical activity in this group.