IJCS | Volume 32, Nº4, July/August 2019

365 20 to 80 years by cycle ergometer test and found a difference in VO 2 max measured by the equations of 36.17% and 26.47% for men and women, respectively, with higher values obtained by the equations. 17 Neder et al., 18 conducted a study with 120 physically inactive volunteers and observed an increment in VO 2 by 14.71% among men and 22.29% among women. Most studies have used the cycle ergometer test for this comparison, and reported VO 2 values 5-11% lower than those obtained from treadmill tests. However, in the American continent, the treadmill exercise test is the most commonly performed, mainly the BP. 19 In our study sample, results obtained from the treadmill test were even higher, maybe because we have used a treadmill ergometer. Similar to our study, Fairbam et al., 17 also reported the biggest differences in VO 2 max among men, although they used an ergometer cycle to assess aerobic capacity. In a nation-wide Brazilian study published in 2011, Peserico et al., 20 assessed aerobic capacity in trained female runners, by measuring VO 2 max both by direct method and indirectly by Foster’s formula (1996) using a treadmill ergometer. The authors found that VO 2 was significantly underestimated when estimated by the prediction formula as compared with direct analysis of gases, indicating substantial limitations of the approach in determining functional capacity in these individuals. 20 Most of previous studies reported contrasting results, showing an overestimation of the VO 2 max indirectly estimated by regression and conventional ergometer test, regardless of the protocol and type of ergometer used. 21,22 Also, according to Santos 21 and Rondon et al., 22 the results of VO 2 max obtained by indirect measurement are influenced by cardiorespiratory fitness of the study subjects. In these studies, greater VO 2 max values, estimated by the ACSM formula, were higher in individuals with poor cardiorespiratory fitness than in those with moderate fitness. These findings suggest that both the type of exercise test protocol and the type of prediction formulas may affect VO 2 estimation, by either overestimating or underestimating the true values. Our study was the first to perform treadmill ergometer exercise test in a group composed of both men and women, young and older subjects, physically active and inactive individuals for a comparative analysis of VO 2 max directly measured by CPET with that estimated by formulas. VO 2 prediction equations derive from studies conducted in North America and Europe. Thus, the results may not be extended to other populations, as pointed by Ong et al., 15 The formula used in the BP 1 was Figure 2 - Null hypothesis of agreement between the methods (Kappa = 0.0034; chi² = 0.001; p = 0.3713) based on the American Heart Association classification of the aerobic capacity; CPET: cardiopulmonary exercise testing; BP: Bruce protocol. CPET Men CPET Women BP Men BP Women Low Moderate High Very high Herdy & Souza Comparison of direct and estimatedVO 2 Int J Cardiovasc Sci. 2019;32(4):362-367 Original Article