Validity and reliability of the modified shuttle walk test in patients with chronic obstructive pulmonary disease

Objectives: (1) To examine the concurrent criterion validity of the modified shuttle walk test (MSWT) by using the 6(6MWT) and 12-minute walk test (12MWT), (2) to examine the concurrent criterion validity of the estimated maximum oxygen uptake (Vo(2)max) of the MSWT with actual Vo(2)max, and (3) to determine test-retest reliability of the MSWT in patients with chronic obstructive pulmonary disease (COPD). Design: Validation study. Setting: Outpatient pulmonary rehabilitation program. Participants: Thirty clinically stable adults with COPD. Interventions: Not applicable. Main Outcome Measures: Subjects were randomly assigned to receive either the 6MWT and 12MWT or the MSWT first. The MSWT was repeated 1 week later (N=30). Estimated Vo2max was calculated, and actual Vo2max was conducted by using the Jones test. Validity of the MSWT was assessed by comparing endurance scores and Vo(2)max with results from the 6MWT and 12MWT and Jones test, respectively. Results: There was a moderately high correlation between the MSWT and the 6MWT and 12MWT at initial testing (.82 and .74, respectively). Correlation between estimated and actual Vo(2)max was r equal to .68. Test-retest reliability for the entire sample was high (intraclass correlation coefficient, .88). Results remained quite stable across severity, age, and sex subgroups. Conclusions: The MSWT is a standardized externally paced submaximal endurance walking test. The results indicate that the MSWT has high concurrent validity and test-retest reliability for patients with COPD.