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

The 6 min walk test (6MWT) is used in clinical and epidemiological practice as a simple tool to evaluate the maximal aerobic exercise capacity (VO₂max). To date, little evidence has been provided regarding regression equation models to predict VO₂max in older adults. Therefore, the main purpose of the study was to develop a reference equation to estimate objectively measured VO₂max, based on the 6MWT, sex, age and body mass index (BMI).

In this observational prospective study, we collected the data from 233 asymptomatic participants aged 60-80 years (52.4% women). VO₂max and the 6MWT were measured using standardized protocols. BMI was calculated as weight (kg) divided by height squared (m²). To be able to develop the predictive equation for VO₂max, we used linear generalized estimating equations (GEE).

Older men performed better in VO₂max (30.9 ± 8.8 vs. 26.3 ± 6.3 mL/kg/min, p < 0.001) and the 6MWT (673.9 ± 58.7 vs. 642.3 ± 48.0 m, p < 0.001), compared to women. VO₂max 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 VO₂max included: VO₂max (mL/kg/min) = 59.44 - 3.83 *, sex (1-men; 2-women) - 0.56 *, age (years) - 0.48 *, BMI (kg/m²) + 0.04 *, and the 6MWT (m) (R = 0.85; R² = 72.3%, SEE = 3.99 mL/kg/min, p < 0.001).

The newly developed regression equation can be a guideline in clinical and epidemiological practice to predict the VO₂max in apparently healthy older adults.