Physical activity in idiopathic pulmonary fibrosis

Introduction: Physical activity (PA) is reduced in IPF and related to mortality predictors. This study aims to describe PA in IPF and evaluate its association with clinical parameters, exercise capacity, muscular strength and health-related quality of life (HRQL). Methods: 17 IPF patients were included. Clinical data was collected; pulmonary function tests, 6-minute walk test (6MWT), respiratory and peripheral muscle strength, body mass index and body composition were performed; patients completed dyspnea scale, Hospital anxiety and depression scale and St. George’s Respiratory Questionnaire (SGRQ). GAP index (Gender-Age-Physiology) was calculated. The following PA parameters were measured with accelerometer: steps/day, time on moderate-vigorous PA/day (MVPA), energy expenditure/day (EE) and PA level (PAL). All variables were compared by PA (steps/day) and PA variables were compared by GAP index; correlations were established between PA variables, exercise capacity and muscular strength. Results: Patients performed a median (p25-p75) of 4393(2444-6919) steps/day, 37(22-51) minutes of MVPA, EE of 1384(713-1630) J and a PAL of 1.3(1.2-1.4). Those with lower PA had higher SGRQ score. GAP III patients performed significantly less PA compared to GAP I-II. There was significant correlation between 6MWT distance and all PA variables. Quadriceps strength correlated with MVPA (r=0.486; p=0.048), EE (r=0.647; p=0.005), and PAL (r=0.56;p=0.03); hand-grip correlated with steps/day (r=0.491;p=0.045), MVPA (r=0.531;p=0.028) and EE (r=0.557;p=0.016). Conclusions: IPF patients with lower PA presented worse HRQL. Those in GAP III stage (worst prognosis) performed less PA. Peripheral muscular strength was positively correlated with PA variables.