Influence of age in estimating maximal oxygen uptake

Objective To assess the influence of age on the error of estimate (EE) of maximal oxygen uptake (VO₂max) using sex and population specific-equations in cycle ergometer exercise testing, since estimated VO₂max is associated with a substantial EE, often exceeding 20%, possibly due to intrinsic variability of mechanical efficiency. Methods 1850 adults (68% men), aged 18 to 91 years, underwent maximal cycle ergometer cardiopulmonary exercise testing. Cardiorespiratory fitness (CRF) was assessed relative to sex and age [younger (18 to 35 years), middle-aged (36 to 60 years) and older (> 60 years)]. VO₂max [mL?(kg?min)^?1] was directly measured by assessment of gas exchange and estimated using sex and population specific-equations. Measured and estimated values of VO₂max and related EE were compared among the three age- and sex-specific groups. Results Directly measured VO₂max of men and women were 29.5 ± 10.5 mL?(kg?min)^?1 and 24.2 ± 9.0 mL?(kg?min)^?1 (P < 0.01). EE [mL?(kg?min)^?1] and percent errors (%E) for men and women had similar values, 0.5 ± 3.2 and 0.4 ± 2.9 mL?(kg?min)^?1, and ?0.8 ± 13.1% and ?1.7 ± 15.4% (P > 0.05), respectively. EE and %E for each age-group were, respectively, for men: younger = 1.9 ± 4.1 mL?(kg?min)^?1 and 3.8 ± 10.5%, middle-aged = 0.6 ± 3.1 mL?(kg?min)^?1 and 0.4 ± 10.3%, older = ?0.2 ± 2.7 mL?(kg?min) ^?1 and ?4.2 ± 16.6% (P < 0.01); and for women: younger = 1.2 ± 3.1 mL?(kg?min) ^?1 and 2.7 ± 10.0%, middle-aged = 0.7 ± 2.8 mL?(kg?min)?1 and 0.5 ± 11.1%, older = -0.8 ± 2.3 mL?(kg?min)^?1 and ?9.5 ± 22.4% (P < 0.01). Conclusion VO₂max were underestimated in younger age-groups and were overestimated in older age groups. Age significantly influences the magnitude of the EE of VO₂max in both men and women and should be considered when CRF is estimated using population specific equations, rather than directly measured.