Abstract 3105: VO2@RER1.0: A Novel Submaximal Cardiopulmonary Exercise Index
VO2max is the gold standard to assess functional capacity but is dependent on subject motivation. Anaerobic threshold (AT) as a submaximal surrogate of VO2max is limited by subjectivity and difficulty identifying this point in some cases. Early in exercise, VO2 < VCO2; at some point after AT, VO2 = VCO2. The point where VO2@VCO2 (VO2@RER1.0) is easy to identify without subjectivity.
Hypothesis: VO2@RER1.0 predicts the likelihood of reaching a normal or abnormal VO2max.
Methods: Between 2/96 and 7/04 139 pediatric subjects (age range 7–18 yrs; 51% males) exercised (bike) to exhaustion; all reached a peak HR ≤ 180, RER ≤ 1.10, and achieved a peak VO2 > 80% predicted (CONTROLS; n = 107) or a peak VO2 < 60% predicted (TEST group; n=32). Primary indication for the TEST group: cardiomyopathy, n=15; repaired congenital heart, n=14; heart transplant, n=2; palpitation, n=1. Using the CONTROLS, linear regression equations were made for VO2@RER1.0 as a function of VO2max predicted and for -2 standard deviations below the mean (figure⇓). TEST subjects were overlayed onto this plot; contingency table analysis was used to compare the two groups.
Results: VO2@RER1.0 and predicted VO2max in normal subjects correlated well (r = 0.84, p<0.0001). 27 TEST subjects had a VO2@RER1.0 which fell below -2SD predicting they would achieve a low peak VO2 (84% sensitivity, 96% specificity, positive predictive value = 87%, negative predictive value = 95%).
Conclusion: VO2@RER1.0 is highly sensitive, specific and predictive of the ability to achieve normal or abnormal peak VO2. This submaximal index will aid in the evaluation of subjects who cannot exercise to maximal parameters.