ESTIMATING FITNESS IN OLDER ADULTS

Abstract

This study evaluated the validity of the Long Distance Corridor Walk (LDCW) as a low cost alternative to treadmill-based assessment of cardiorespiratory fitness in older adults. The LDCW consist of: 1) a 2-min warm-up walk (“covering as much ground as possible”) that also serves as a stepped-down test for those unable to walk for a longer period and 2) a 400m walk “done as quickly as possible”. The 400m component has been found to encourage greater effort than time-limited tests, such as the 6-min walk. Overall and sex-specific equations for estimating VO2max using time to walk 400m, age, race, HR and BP response, perceived effort, height, weight, stride length, and activity level were also developed. The study population consisted of 56 men and 46 women aged 60–91 participating in the Baltimore Longitudinal Study on Aging who had a maximal treadmill test with measured O2 consumption. Subjects did the LDCW the day after treadmill testing on a 20m course. VO2max ranged from 12.2 - 31.1 ml O2/kg/min and time on the 400m walk ranged from 2:52 to 6:18. The correlation between 400m walk time and VO2max was −0.79. The linear regression equation including all variables listed explained 76% of the variance in VO2max. Using a stepwise procedure, only 400m walk time (partial R2 = .625), stride length (partial R2 = 0.55), and ending SBP (partial R2 = 0.32) entered the model explaining 74% of the variance in VO2max. The LDCW provides a valid estimate of cardiorespiratory fitness in older adults. Time to walk 400m with adjustment for stride length and effort, as indicated by ending SBP, produces remarkably close estimates of VO2max, correlating 0.82 for men and 0.86 for women with that determined from a maximal treadmill test.