This systematic review examined the measurement properties of the 6-min walk test (6MWT), incremental shuttle walk test (ISWT) and endurance shuttle walk test (ESWT) in adults with chronic respiratory disease.
Studies that report the evaluation or use of the 6MWT, ISWT or ESWT were included. We searched electronic databases for studies published between January 2000 and September 2013.
The 6-min walking distance (6MWD) is a reliable measure (intra-class correlation coefficients ranged from 0.82 to 0.99 in seven studies). There is a learning effect, with greater distance walked on the second test (pooled mean improvement of 26 m in 13 studies). Reliability was similar for ISWT and ESWT, with a learning effect also evident for ISWT (pooled mean improvement of 20 m in six studies). The 6MWD correlates more strongly with peak work capacity (r=0.59–0.93) and physical activity (r=0.40–0.85) than with respiratory function (r=0.10–0.59). Methodological factors affecting 6MWD include track length, encouragement, supplemental oxygen and walking aids. Supplemental oxygen also affects ISWT and ESWT performance. Responsiveness was moderate to high for all tests, with greater responsiveness to interventions that included exercise training.
The findings of this review demonstrate that the 6MWT, ISWT and ESWT are robust tests of functional exercise capacity in adults with chronic respiratory disease.