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.

Six minute walk distance in healthy subjects aged 55-75 years.

BACKGROUND: The six minute walk test (6MWT) is the most commonly used exercise test in pulmonary rehabilitation; however, the paucity of six minute walk distance (6MWD) reference values from population-based samples limits data interpretation in patients. This study was undertaken to determine 6MWD in a population-based sample of healthy subjects and to identify predictors of 6MWD in this group. METHODS: Seventy Caucasian subjects (33 males) aged 55-75 years performed three tests using a standardised protocol. 6MWD was defined as the greatest distance achieved from the three tests. Other measurements included height, leg length, weight, forced expiratory volume in 1s (FEV(1)), exhaled carbon monoxide and self-reported physical activity including habitual walking. RESULTS: The average 6MWD was 659+/-62 m (range 484-820 m). Males walked 59+/-13 m further than females (P<0.001). Height (r=0.54, P<0.01), weight (r=0.25, P<0.05) and FEV(1) (r=0.48, P<0.001) were significantly correlated with 6MWD. Forwards stepwise multiple regression showed height (R(2)=0.294) and FEV(1) (R(2) change=0.045) to be independent predictors of 6MWD (P<0.05), explaining 33.9% of the variance. CONCLUSIONS: 6MWD in this healthy population-based sample of males and females exceeds values previously reported. Height and FEV(1) were identified as significant independent predictors of 6MWD in this group.