Reproducibility of walking at self-preferred and maximal speed in patients with postpoliomyelitis syndrome

Objective: To assess the reproducibility of walking performance, heart rate, and perceived exertion at self-preferred speed and maximal walking speed in patients with the post-poliomyelitis syndrome (PPS). Design: Repeated measurement at a 3-week interval. Setting: University hospital. Participants: Convenience sample of 65 patients with PPS. Interventions: Not applicable. Main Outcome Measures: Walking performance: the distance walked in 2 minutes at a self-preferred speed and the time needed to walk 75m at maximal speed, heart rate, and rating of perceived exertion (RPE) on an 11-point scale. Results: Test-retest reliability of walking performance was excellent for both tests (intraclass correlation coefficient [ICC] range,.94-97). No systematic differences existed between test and retest. The smallest detectable change for an individual was 15% for both tests. Test-retest reliability for heart rate was good (ICC=.86) but moderate for RPE (Spearman p range,.67-70). The smallest detectable change for RPE was between 4 and 6 scale points. The variability in walking performance was significantly correlated with the variability in heart rate at self-preferred speed (r=.36, P<.01) but not with the variability in RPE (r=.20, P=.11). Conclusions: Both walking tests showed good reproducibility and may be appropriate to monitor (individual) changes in walking capacity in patients with PPS. Because of its moderate reproducibility, RPE does not seem to be suitable to monitor physical exertion. The usefulness of an objective measure such as heart rate for this purpose needs further investigation.