Timed “up and go” to identify physically inactive individuals with interstitial lung disease

Abstract

Objective: To investigate the relationship between the timed “up and go” (TUG) test and physical activity in daily life (PADL) in patients with interstitial lung disease (ILD) and propose a cutoff point to identify physically inactive individuals. Methods: Participants performed the TUG test at a usual pace (TUGusual) and at a fast pace (TUGfast). Exercise capacity was assessed by the six-minute walk test, lung function was assessed by whole-body plethysmography, quadriceps strength was assessed by maximal voluntary isometric contraction, and PADL was assessed by an activity monitor worn for six consecutive days. PADL variables included number of steps/day, time spent/day in activities of different intensities, and time spent/day in different postures. A ROC curve was plotted to identify physically inactive individuals on the basis of daily steps (5,000 steps/day) and moderate to vigorous physical activity (MVPA; 30 min/day). Results: Fifty-three ILD patients (26 women, with a mean age of 60 ± 11 years) were included in the study. TUGusual and TUGfast correlated moderately with the number of steps/day and time spent/day in light physical activity and MVPA (−0.60 < r < −0.41; p < 0.05 for all). ROC curves for TUGusual showed that the cutoffs of ≥ 9.25 s and ≥ 7.9 s can identify physically inactive individuals on the basis of 5,000 steps/day (AUC: 0.73; sensitivity, 76%; specificity, 70%) and 30 min/day of MVPA (AUC: 0.85; sensitivity, 90%; specificity, 75%). Participants who performed worse on TUGusual (i.e., ≥ 9.25 s) showed lower peripheral muscle strength, exercise capacity, and PADL. Conclusions: Performance on TUGusual and TUGfast correlates moderately with PADL in patients with ILD. A TUGusual performance ≥ 9.25 s appears to be able to identify physically inactive individuals in this population.