title: Influence of age in estimating maximal oxygen uptake.
abstract: 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 VO2 max 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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Heart Institute Edson Saad and Medical School, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil; Exercise Medicine Clinic, CLINIMEX, Rio de Janeiro, RJ, Brazil.
authors.forename: Christina G
authors.initials: CG
authors.lastname: de Souza E Silva
authors.affiliation: Preventive Cardiology and Cardiac Rehabilitation, William Beaumont Hospital, Royal Oak, MI, United States.
authors.forename: Barry A
authors.initials: BA
authors.lastname: Franklin
authors.affiliation: Section of Geriatric Cardiology, University of Pittsburgh Medical Center, Geriatrics, Research, Education, and Clinical Center, VA Pittsburgh Healthcare System, University of Pittsburgh, Pittsburgh, PA, USA.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Forman
authors.affiliation: Heart Institute Edson Saad and Medical School, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil; Exercise Medicine Clinic, CLINIMEX, Rio de Janeiro, RJ, Brazil.
authors.forename: Claudio Gil S
authors.initials: CG
authors.lastname: Araújo
keywords: Aging; Cardiopulmonary exercise testing; Error of measurement