Abstract

The kinetics of oxygen uptake (V02), carbon dioxide output (VC02), and expired ventilation (VE) in the transition from rest or from prior exercise were studied in response to step increases in power output (PO). The data are modeled with a single-component exponential function incorporating a time delay (TD). Each subject exercised on four occasions. Test 1 was an incremental test for determination of ventilatory anaerobic threshold (AT). Step increase tests were rest to 80 of PO at AT (test 2), rest -40 AT (3a), 40-80 AT (3b), rest -40 AT (4a), and 40-120 AT (4b). Respiratory gas exchange was monitored by open-circuit techniques. The V02 kinetics showed the time constant (r) to be longer in the transitions from prior exercise than from rest. Kinetic analysis for VC02 showed a tendency for r to be shorter for the tests from prior exercise, but neither r nor r + TD were significantly different between tests. In contrast to VC02, VE kinetics showed a significantly longer r + TD for test 3b and test 4b. This study has shown the V02 kinetics to be delayed when a given increment in PO occurred from prior exercise, whether the final PO was below or above the AT. Further, the dissociation of VC02 and VE kinetics does not support a direct link between these two variables as the sole control factor in exercisehyperpnea.Verf.-Referat