Regression equations to predict 6-minute walk distance in middle-aged and elderly adults

Six-minute walk distance (6MWD) is commonly used as a measure of functional exercise capacity in clinical practice and research. Regression equations to predict 6MWD in healthy individuals are available, but the equations predict distances that vary considerably for an individual. The aims of this study were to 1) measure 6MWDs in healthy Caucasian Australians aged 45-85 years; 2) determine whether evidence exists for Australian-specific prediction equations for Caucasian individuals by comparing measured 6MWDs with predicted 6MWDs derived by using published regression equations; and 3) develop regression equations for males and females. One hundred nine subjects (48 males) completed the 6-minute walk test (6MWT). Measurements of height, leg length, weight, habitual physical activity, and peak heart rate (HR) achieved during the 6MWT were obtained. 6MWD (better of two tests) was 682 +/- 73 m (mean +/- SD) and 643 +/- 70 m in the males and females, respectively (p<0.01). Published regression equations underestimated 6MWDs in female subjects. Gender-specific regression equations using age and anthropometric data explained 40% and 43% of the variance in 6MWD in males and females, respectively. Validation of the regression equations in a prospective subject cohort is required.