INTRODUCTION: The importance of maximal oxygen consumption (<img border=0 id="_x0000_i1032" src="/img/revistas/rbme/v18n3/v.jpg" align=absmiddle>O2máx) measurement is justified by its international acceptance as the best physiological parameter to assess the functional capacity of the cardiorespiratory system in both athletes and non-athletes who physically train in order to achieve better health. OBJECTIVE: To determine the agreement between the Polar Fitness Test® protocols to estimate of <img border=0 id="_x0000_i1033" src="/img/revistas/rbme/v18n3/v.jpg" align=absmiddle>O2máx and the maximal exercise test with direct gas measurement. METHODS: Seventeen active males (22.5 ± 2 years) participated in the study. At rest, the Polar Fitness Test® protocol by direct gas collection under maximum effort on treadmill and the Bruce protocol were applied. RESULTS: Significant difference in the <img border=0 id="_x0000_i1034" src="/img/revistas/rbme/v18n3/v.jpg" align=absmiddle>O2máx estimation was observed between methods. The Polar Fitness Test® protocol underestimated <img border=0 id="_x0000_i1035" src="/img/revistas/rbme/v18n3/v.jpg" align=absmiddle>O2máx a mean of 15% (CI95%: 24;-53%) when compared to the direct protocol. The values obtained by the Polar Fitness Test® did not correlate well with direct measurement in ergospirometer (r = 0.1). CONCLUSION: The Polar Fitness Test® protocol is not valid to estimate <img border=0 id="_x0000_i1036" src="/img/revistas/rbme/v18n3/v.jpg" align=absmiddle>O2máx in physically active young men.
efficiency; oxygen consumption; ergospirometer; estimation; heart rate