Estimating cardiorespiratory fitness in well-functioning older adults: Treadmill validation of the Long Distance Corridor Walk

OBJECTIVES: To determine criterion validity of the 400-m walk component of the Long Distance Corridor Walk (LDCW) and develop equations for estimating peak oxygen consumption (VO2) from 400-m time and factors intrinsic to test performance (e.g., heart rate (HR) and systolic blood pressure (SBP) response) in older adults. DESIGN: Cross-sectional validation study. SETTING: Gerontology Research Center, National Institute on Aging, Baltimore, Maryland. PARTICIPANTS: Healthy volunteers (56 men and 46 women) aged 60 to 91 participating in the Baltimore Longitudinal Study of Aging between August 1999 and July 2000. MEASUREMENTS: The LDCW, consisting of a 2-minute walk followed immediately by a 400-m walk "done as quickly as possible" over a 20-m course was administered the day after maximal treadmill testing. HR and SBP were measured before testing and at the end of the 400-m walk. Weight, height, activity level, perceived effort, and stride length were also acquired. RESULTS: Peak VO2 ranged from 12.2 to 31.1 mL oxygen/kg per minute, and 400-m time ranged from 2 minutes 52 seconds to 6 minutes 18 seconds. Correlation between 400-m time and peak VO2 was -0.79. The estimating equation from linear regression included 400-m time (partial coefficient of determination (R-2)=0.625), long versus short stride (partial R-2=0.090), ending SBP (partial R-2=0.019), and a correction factor for fast 400-m time (< 240 seconds; partial R-2=0.020) and explained 75.5% of the variance in peak VO2 (correlation coefficient=0.87). CONCLUSION: A 400-m walk performed as part of the LDCW provides a valid estimate of peak VO2 in older adults. Incorporating low-cost, safe assessments of fitness in clinical and research settings can identify early evidence of physical decline and individuals who may benefit from therapeutic interventions.