A Simple Equation to Estimate Maximal Oxygen Uptake in Older Adults Using the 6 min Walk Test, Sex, Age and Body Mass Index

Purpose: The 6 min walk test (6MWT) is used in clinical and epidemiological practice as a simple tool to evaluate the maximal aerobic exercise capacity (VO(2)max). To date, little evidence has been provided regarding regression equation models to predict VO(2)max in older adults. Therefore, the main purpose of the study was to develop a reference equation to estimate objectively measured VO(2)max, based on the 6MWT, sex, age and body mass index (BMI). Patients and Methods: In this observational prospective study, we collected the data from 233 asymptomatic participants aged 60-80 years (52.4% women). VO(2)max and the 6MWT were measured using standardized protocols. BMI was calculated as weight (kg) divided by height squared (m(2)). To be able to develop the predictive equation for VO(2)max, we used linear generalized estimating equations (GEE). Results: Older men performed better in VO(2)max (30.9 & PLUSMN; 8.8 vs. 26.3 & PLUSMN; 6.3 mL/kg/min, p < 0.001) and the 6MWT (673.9 & PLUSMN; 58.7 vs. 642.3 & PLUSMN; 48.0 m, p < 0.001), compared to women. VO(2)max was correlated with the 6MWT (r = 0.71, p < 0.001), sex (r = -0.29, p < 0.001), age (r = -0.62, p < 0.001) and BMI (r = -0.38, p < 0.001). The model to predict VO(2)max included: VO(2)max (mL/kg/min) = 59.44 - 3.83 *, sex (1-men; 2-women) - 0.56 *, age (years) - 0.48 *, BMI (kg/m(2)) + 0.04 *, and the 6MWT (m) (R = 0.85; R-2 = 72.3%, SEE = 3.99 mL/kg/min, p < 0.001). Conclusion: The newly developed regression equation can be a guideline in clinical and epidemiological practice to predict the VO(2)max in apparently healthy older adults.

Automated summary

The purpose of this study was to develop a reference equation to estimate objectively measured VO(2)max in older adults based on the 6 min walk test, sex, age, and body mass index (BMI).