VO2 kinetics in supra-anaerobic threshold constant tests allow the visualization and quantification of the O2 saving after cytochrome C oxidase inhibition by aerobic training or nitrate administration

We tested whether the known cytochrome c oxidase (COX) inhibition by nitric oxide (NO) could be quantified by VO 2 kinetics during constant load supra-Anaero bic Threshold (AT) exercises in healthy trained or untrained subjects following aerobic training or nitrate administration. In cycle er gometer constant load exercises supra-AT, identified in previous incremental tests, VO 2 kinetics describe a double exponential curve, one rapid and one appreciably slower, allowing the area between them to be calculate in O 2 l. After training, with increased NO availability, this area decreases in inverse ratio to treatment efficacy. In fact, in 11 healthy subjects after aerobic tr aining for 6-7 weeks, area was decreased on average by 51 %. In 11 untrained subjects, following the assumption of an NO donor, 20 mg isosorbide 5 mononitrate, area was decrea sed on average by 53 %. In conclusion, supra-AT VO 2 kinetics in constant load exercises permit the quantification of the inhibitory effect NO-dependent on COX after either physical training or nitrate assumption.