VALIDATION OF A COMPUTERIZED TECHNIQUE FOR DETECTION OF THE GAS-EXCHANGE ANAEROBIC THRESHOLD IN CARDIAC DISEASE

Respiratory gas exchange data were collected from 77 men >6 months after acute myocardial infarction. Maximal exercise was performed on an ergometer cycle programmed for a ramp protocol of 15 W/min. The gas exchange anaerobic threshold (ATge) was determined by analysis of the carbon dioxide elimination (V̇CO2) vs oxygen consumption (V̇O2) curve below a respiratory exchange ratio of 1.00 using a computerized algorithm. This value was estimated at the inflection of V̇CO2 from a line with a slope of 1 which intersects the V̇CO2 vs V̇O2 curve. The relation of the ATge to the lactate acidosis threshold was studied in 29 patients. The reproducibility of the ATge method was studied in 77 patients. Mean (± standard deviation) V̇O2 for the ATge was 905 ± 220 vs 866 ± 299 ml/min for the lactate acidosis threshold (r = 0.86, p < 0.001). Mean V̇O2 at the ATge for test 1 was 968 ± 225 vs 952 ± 217 ml/min for test 2 (r = 0.71, p < 0.001). Mean peak V̇O2 was 1,392 ± 379 vs 912 ± 202 ml/min at the ATge (r = 0.76, p < 0.001). Results demonstrate that this ATge method correlates well with the lactate acidosis threshold, is reproducible, and should be useful as an objective measure of submaximal exercise performance. © 1990.