Reliability of a timed walk test in persons with acquired brain injury

OBJECTIVE: The purpose of this study was to assess the reliability of a 6-min walk test in individuals with acquired brain injury. DESIGN: A total of 23 clients (14 men, 9 women) participated. All participants were clients in a postacute residential rehabilitation facility. The time from injury averaged 12 mo (range, 7-38 mo). Subjects were instructed to walk around a rectangular track as many times as possible during a period of 6 min. The test was performed twice, separated by 1-10 days. Heart rate was monitored continuously throughout the test, and distance traveled was recorded in meters after completion. A physiologic cost index (beats per meter) was calculated. Intraclass correlation coefficients were calculated for distance traveled, heart rate responses, and physiologic cost index. RESULTS: The mean distance walked was 403 +/- 105 m (trial 1) and 417 +/- 106 m (trial 2). The intraclass correlation coefficient for distance was 0.94. The mean steady-state heart rate was 118 +/- 21 beats/min (trial 1) and 117 +/- 20 beats/min (trial 2), and the intraclass correlation coefficient was 0.65. The mean physiologic cost index was 0.52 +/- 0.19 beats/m (trial 1) and 0.55 +/- 0.22 beats/m (trial 2), and the intraclass correlation coefficient was 0.89. CONCLUSIONS: Distance traveled and the physiologic cost index demonstrated excellent reliability, whereas heart rate responses for individual minutes demonstrated only fair reliability. The individuals studied were very consistent in their efforts, despite a combination of physical and cognitive impairments. The results suggest that the 6-min walk test can be used reliably in the assessment of functional ambulation in persons with acquired brain injury.