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.