Reliability and validity of the 6-min walk test in adults and seniors with intellectual disabilities

• Validity and reliability evaluation of the 6MWT in adults and seniors with ID.
• The 6MWT was found to be a valid and a reliable test in this population.
• Isometric leg strength and relative VO2 peak are significant predictors of this test.
• We recommend performing at least one practice trial to obtain reliable scores.

IntroductionAdults with intellectual disabilities (ID) have significantly lower rates of physical activity and fitness than adults without ID. The 6-min walk test (6MWT) is an inexpensive and simple way to test mobility and submaximal work capacity.PurposeTo evaluate the test–retest reliability and validity of the 6MWT in adults and seniors with ID and explore factors contributing to the 6MWT distance (6MWD).Methods46 participants with mild, moderate and severe ID levels (age = 41 ± 11 years) performed the 6MWT three times (T1; T2; T3) to determine test–retest reliability. To test validity, peak oxygen uptake (VO2 peak) was measured using a treadmill protocol. To analyze factors contributing to the 6MWD, sex, height, fat mass % and fat free mass %, ID level, isometric leg strength and relative VO2 peak were also measured.ResultsThe walking distances for T1, T2 and T3 were 460.3 ± 76.9; 489.4 ± 81.2 and 491.4 ± 77.9 m, respectively. The 6MWDs between T1–T2 and T1–T3 were significantly different (p < 0.001), but T2 and T3 were not different. The intraclass correlation coefficient between T2 and T3 was 0.96 indicating high reliability. Relative VO2 peak and isometric leg strength significantly contributed to the 6MWD (R2 = 0.55).ConclusionsThe 6MWT is an easy, inexpensive, reliable and valid test in adults and seniors with ID. Familiarization is necessary to obtain reliable values. Relative VO2 peak and leg strength have significant impact on the distance walked.