Validating a Nonmotorized Treadmill Across Age and Sex for the Traditional Overground 6-min Walk Test in Healthy Adults

ABSTRACT Introduction The 6-min walk test (6MWT) is a traditional test used in clinical and research settings to assess physical function. However, in many settings, the 30-m corridor required to conduct the test may not be available. The use of a nonmotorized treadmill (NMT) as an alternative has not been well studied. The primary purpose of this study was to assess the validity of using a NMT as a replacement for the traditional (TRAD) 6MWT. Methods A total of 55 healthy adults (28 females) completed the TRAD and NMT 6MWTs on the same day to assess interrater reliability. The levels of agreement between the two modes were quantified using Lin’s concordance correlation coefficients. Additionally, a multiple linear regression was done to predict TRAD 6MWT distance with covariates of age, sex, height, and weight from NMT 6MWT distance walked. Results The average 6MWT distance was 630 m for TRAD and 607 m for NMT. There was a very large level of agreement between modes ( r c = 0.84). A multiple linear regression was developed and revealed that NMT 6MWT distance significantly predicted TRAD 6MWT distance when controlling for age, sex, height, and weight ( R 2 = 0.80, P < 0.001). Conclusion The use of NMT for 6MWT is a valid replacement for the TRAD 6MWT based on the results of this study.