IJCS | Volume 32, Nº4, July/August 2019

364 VO 2 max estimated by the BP and the CPET (38.85 ± 3.72 mL/Kg.min versus 26.83 ± 3.90mL/Kg.min, respectively, p < 0.0001) for women, and for men (45.94 ± 3.94 mL/ Kg.min versus BP 34.26 ± 4.21 mL/Kg.min, respectively, p < 0.0001) The BP overestimated VO 2 max by 44.8% for women and by 34.1% for men compared with the CPET. No difference was found in maximal effort, measured bymaximal heart rate (HRmax) between the tests. During the BP and CPET, HR max was 184.8 ± 9.47 vs 183.1 ± 10.03, respectively, for men, and 179.8 ± 11.68 versus 180.8 ± 12.63, respectively, for women, p = NS). There was a moderate correlation between the two methods (r = 0.65), and the agreement between the tests regarding cardiorespiratory fitness was null (Figure 2) (Kappa = 0.0034 and chi-square = 0.001). Most participants showed high or very high cardiorespiratory fitness by the BP and moderate or low cardiorespiratory fitness according to the CPET. Discussion Cardiorespiratory fitness has been shown to be an important prognosticmarker ofmorbidity andmortality in young, older, healthy individuals with heart diseases. 8,15,16 Most studies have classified individuals according to their performance in ergometric tests. In Brazil and in the USA, the ergometric test on the treadmill has beenwidely used, and the BP is the main test performed. 14 Although individual risk to stress tests may be stratified by test duration, functional capacity may be overestimated in young adults, even in physically inactive ones. In this regard, when age range is used for risk stratification, conventional stress test is not an accurate test to evaluate functional capacity. Sedentary habits have long-term, cumulative effects, and several studies have shown that it is never too late to decrease the risk by improving physical fitness. In most computer programs for exercise stress testing in Brazil, VO 2 is estimated using the BP formula, and used to classify subjects according to cardiorespiratory fitness. Our study showed an important overestimation of the indirect assessment of VO 2 by the BP. In 1973, Bruce et al., 1 studied 295 physically active or inactive adults by exercise testing on the treadmill, and direct analysis of gases, fromwhich derived the formulas currently used. Ong et al., 4 measured VO 2 max by CPET and compared it with that obtained by cycle ergometer test (prediction equations). The formulas overestimated the results by 13.74% for men and 10.55% formwomen. 4 Fairbarn et al., 17 evaluated 231 non-athletes aged from Figure 1 - Comparison of VO 2 max in Young, physically inactive individuals by sex (men; n = 20 and women; n = 21), p < 0.0001 (mean ± SD); VO 2 : oxygen uptake; CPET: cardiopulmonary exercise testing. Female Male 38.84 ± 3.72 45.95 ± 3.94 26.83 ± 3.90 34.27 ± 4.20 38.94 ± 4.12 46.76 ± 4.38 VO 2 by Bruce protocol (mL/kg.min) VO 2 by CPET (mL/kg.min) Predicted VO 2 (mL/kg.min) Herdy & Souza Comparison of direct and estimatedVO 2 Int J Cardiovasc Sci. 2019;32(4):362-367 Original Article