Maximal oxygen consumption (\( \dot{V}_{\text{O}_{2}}\text{max}\)) is the “gold standard” by which to assess functional capacity; however, it is effort dependent. \(\text{V}_{\text{O}_{2}}\)@RER_{1.0} is defined when \(\text{V}_{\text{O}_{2}}={V}_{\text{CO}_{2}}\). Between December 22, 1997 and November 9, 2004, 305 pediatric subjects underwent cycle ergometer cardiopulmonary exercise testing, exercised to exhaustion, and reached a peak respiratory exchange ratio ≥1.10. Group 1 subjects achieved a peak \(\text{V}_{\text{O}_{2}} \ge 80\%\) of predicted \( \dot{V}_{\text{O}_{2}}\text{max}\); group 2 subjects achieved a peak \(\text{V}_{\text{O}_{2}} \le 60\% \) of predicted \( \dot{V}_{\text{O}_{2}}\text{max}\); and group 3 subjects achieved a peak \(\text{V}_{\text{O}_{2}}\) between 61 and 79% of predicted \( \dot{V}_{\text{O}_{2}}\text{max}\). Linear regression analysis was performed for \(\text{V}_{\text{O}_{2}}\)@RER_{1.0} as a function of predicted \( \dot{V}_{\text{O}_{2}}\text{max}\) for group 1 subjects. A −2 SD regression line and equation was created. \( \text{V}_{\text{O}_{2}}\)@RER_{1.0} data from groups 2 and 3 were plotted onto the normative graph. Contingency table and relative-risk analysis showed that an abnormal \( \text{V}_{\text{O}_{2}}\)@RER_{1.0} predicted an abnormal peak \(\text{V}_{\text{O}_{2}}\)(positive-predictive value 83%, negative-predictive value 85%, sensitivity 84%, and specificity 84%). \( \text{V}_{\text{O}_{2}}\)@RER_{1.0} is a highly sensitive, specific, and predictive submaximal index of functional capacity. This submaximal index is easy to identify without subjectivity. This index may aid in the evaluation of subjects who cannot exercise to maximal parameters.