Claudio Gil S. Araújo et al. Claudia Lucia Castro João Felipe Franca Christina Grüne de Souza e Silva
Abstract
Background:
Cardiorespiratory (aerobic) fitness is strongly and directly related to major health outcomes, including all-cause mortality. Maximum oxygen uptake (VO2max), directly measured by maximal cardiopulmonary exercise test (CPET), represents the subject’s aerobic fitness. However, as CPET is not always available, aerobic fitness estimation tools are necessary.
Objectives:
a) to propose the CLINIMEX Aerobic Fitness Questionnaire (C-AFQ); b) to validate C-AFQ against measured VO2max; and c) to analyze the influence of some potentially relevant variables on the error of estimate.
Methods:
We prospectively studied 1,000 healthy and unhealthy subjects (68.6% men) aged from 14 to 96 years that underwent a CPET. The two-step C-AFQ describes physical activities with corresponding values in metabolic equivalents (METs) – ranging from 0.9 to 21 METs.
Results:
Application of C-AFQ took less than two minutes. Linear regression analysis indicated a very strong association between estimated (C-AFQ) and measured (CPET) maximal METs – r2 = 0.83 (Sy.x = 1.63; p < .001) – with median difference of only 0.2 METs between both values and interquartile range (percentiles 25 and 75) of 2 METs. The difference between estimated and measured METs was not influenced by age, sex, body mass index, clinical condition, ß-blocker use or sitting-rising test scores.
Conclusion:
C-AFQ is a simple and valid tool for estimating aerobic fitness when CPET is unavailable and it is also useful in planning individual ramp protocols. However, individual error of estimate is quite high, so C-AFQ should not be considered a perfect substitute for CPET’s measured VO2max.