Reference values for standardized tests of walking speed and distance: a systematic review

To provide an overview of the reference values and methodology used to obtain them for time- and distance-limited walk tests.

We performed a systematic review and searched PubMed, MEDLINE (Ovid), EMBASE, CINAHL, Scopus, PEDro, and The Cochrane Library from 1946 to May 2013. Full-text peer-reviewed articles written in English, French or Spanish were considered eligible. Two authors independently screened titles and abstracts. One author determined eligibility of full-text articles, appraised methodological quality, and extracted data. A second author independently verified the accuracy of extracted data.

Of the 41 eligible studies reviewed, 25 failed to describe the method used to select participants and 10 had an inadequate sample size. Twenty-five studies provided reference values for one time-limited walk test (6-min walk test (6 MWT)) and 18 studies provided reference values for 15 distance-limited walk tests. Across studies, walk test distances ranged from 3m to 40m. Descriptive values and reference equations for the 6 MWT were reported in 15 and 20 studies, respectively. Across 43 regression equations (median R(2)=0.46), age (98%) and sex (91%) were most frequently included. The equation yielding the maximum R(2) value (0.78) included age, height, weight and percentage of predicted maximum heart rate. Among six unique regression equations for distance-limited walk tests (median R(2)=0.17), sex (83%), age (67%) and weight (67%) were most frequently included. The equation yielding the maximum R(2) value (0.25) included age and sex.

Reference values reported for these tests provide a basis for classifying walking capacity as within normal limits, determining the magnitude of deficit, educating clients, setting rehabilitation goals, and planning studies.