Reliability of Cardiorespiratory and Metabolic Responses During Incremental Shuttle Walk Test in Adult Subjects With Asthma

BACKGROUND: The incremental shuttle walk test (ISWT) has been widely used to assess exercise capacity of subjects with COPD. However, to date, no studies have assessed its reliability in the asthmatic population. This study aimed to assess the test-retest reliability of ISWT for the distance walked (ISWD) and cardiorespiratory and metabolic responses in adult subjects with asthma. METHODS: This was a cross-sectional observational study. Thirty-four subjects of both genders, 18-45 y old, with a diagnosis of controlled asthma, were recruited from March 2012 to December 2015. The subjects performed 3 ISWTs on different days, with a minimum interval of 48 h and a maximum of 1 week between the second and third ISWT. For the reliability analysis, the values of the second and third ISWTs were used, eliminating the influence of any learning effect from the first test. RESULTS: The intraclass correlation coefficients were > 0.75 (P < .001) for ISWD (m), speed (km/h),oxygen uptake ((V) over dot(O2)), ventilatory equivalent carbon dioxide ((V) over dot(E)/(V) over dot(CO2)), and minute ventilation ((V) over dot(E)) at the ISWT peak. The Bland-Altman plot presented a mean error close to zero, and measurement distribution was within acceptable limits of variation. CONCLUSION: The ISWT presented excellent reliability for the ISWD and metabolic responses. The cardiorespiratory responses in the ISWTs presented good reliability. We concluded that the ISWT was reliable for young adult subjects with controlled asthma.