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

OBJECTIVE: To provide an overview of the reference values and methodology used to obtain them for time- and distance-limited walk tests. METHODS: 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. RESULTS: 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 R2=0.46), age (98%) and sex (91%) were most frequently included. The equation yielding the maximum R2 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 R2=0.17), sex (83%), age (67%) and weight (67%) were most frequently included. The equation yielding the maximum R2 value (0.25) included age and sex. CONCLUSIONS: 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