Long-term reliability of the incremental shuttle walking test in clinically stable cardiovascular disease patients

ObjectiveThe incremental shuttle walking test (ISWT) is a valuable tool for assessing changes in patients’ functional capacity during cardiac rehabilitation. However, studies have only assessed its test–retest reliability in the short term. The purpose of this study was to examine long-term test–retest reliability of the ISWT in clinically stable cardiac patients.DesignTest–retest reliability assessment.SettingContinuous, community-based phase IV cardiac rehabilitation centre.ParticipantsThirty patients with cardiovascular disease (15 males, 15 females; age 55 to 80 years) volunteered to participate in the study.InterventionsParticipants undertook two ISWTs, a minimum of 8 weeks apart.Main outcome measuresISWT performance in metres.ResultsOverall, the mean distance walked in the pre-test was 502 ± 161 m and this did not differ from test to retest. The intraclass correlation coefficient was 0.80, indicating good test–retest reliability. Using the Bland and Altman method, there was a small mean test–retest difference (−7 m). The 95% limits of agreement were large, ranging from −203 m to 189 m.ConclusionsOver long test–retest durations, there appears to be no learning effect in the ISWT, negating the need for a practice walk. The long-term random variation in the ISWT test is larger than in previous studies, probably due to greater physiological and psychological variation in the participants over 8 weeks compared with that seen in day-to-day testing. Factors influencing long-term test–retest reliability of the ISWT require further elucidation.