Clinical determinants of the incremental shuttle walk test in patients with interstitial lung disease

Abstract

Background : The incremental shuttle walk test (ISWT) is a constantly used measurement of maximal exercise capacity in interstitial lung disease (ILD). While exercise intolerance has been identified in ILD, the clinical determinants of ISWT in this population have not been adequately examined yet. Aim: To investigate the clinical determinants of incremental shuttle walk test in patients with ILD. Methods: Forty-seven patients with ILD (50.06±12.47 years, 32F, 15M) were included. Patients' demographics were recorded. Maximal exercise capacity was evaluated using incremental shuttle walk test (ISWT), respiratory muscle strength (MIP, MEP) using a mouth pressure device, pulmonary functions and diffusing capacity (DLCO) using spirometry, peripheral muscle strength using a hand-held dynamometer, dyspnea using Modified Medical Research Council (MMRC) dyspnea scale, fatigue using Fatigue Severity Scale (FSS), quality of life using Saint George's Respiratory Questionnaire (SGRQ). Results: There were statistically significant correlations between ISWT distance and age, height, sex, MIP, MEP, quadriceps femoris and shoulder flexor muscle strength, DLCO, MMRC and FSS (p<0.05). In the multiple regression analysis, conducted in the 47 patients, 84% of the variance in the ISWT distance was explained by the shoulder flexor muscle strength (R²=0.54 p<0.001), age (R²=0.20 p<0.001) and fatigue (R²=0.10 p<0.001). Conclusions: Upper extremity muscle strength, age and fatigue are demonstrated a stronger determinants of ISWT in patients with ILD. These findings suggest that, resistance training and possible pulmonary rehabilitation approaches alleviating fatigue in patients with ILD are advisable.