Test-retest reliability of the 6-minute walk test in individuals with Down syndrome

Objectives: To evaluate the reliability of the 6-minute walk test (6MWT) in individuals with Down syndrome and explore factors affecting walking distance.

Design: Four repeated walk tests in the span of 2 weeks including 2 practice walks.

Setting: All tests were carried out in a 40-meter corridor at a university sport complex.

Participants: Adolescents and young adults with Down syndrome (N=55) aged 11 to 26 years.

Intervention: Not applicable.

Main outcome measure: Participants were instructed to walk as far as possible for the duration of 6 minutes. Distance walked, heart rate, blood pressure, and perceived exertion were measured across 4 tests (t1, t2, t3, and t4).

Results: The walking distances for t1, t2, t3, and t4 averaged 395, 428, 433, and 436 meters, respectively. The 6-minute walk distance (6MWD) during t1 and t2 was significantly different from that during t3 and t4 (t(54)=-6.475, P<.001). Repeated analysis of variance showed no significant difference between the distance walked in t3 and t4 (433±64m vs 436±68m) (F(1,54)=2.439, P=.124). Body mass index as well as levels of intellectual disability and physical activity all affected the distance walked to different degrees.

Conclusions: The 6MWT showed good test-retest reliability and increased the walking distance after 2 practice walks, emphasizing the need to account for a learning effect among people with Down syndrome. Reported 6MWD appears lower than that previously reported for individuals without Down syndrome.