抄録
In order to study respiratory transients during exercise, we examined breath-by-breath gas exchange kinetics during constant-load work. Five male subjects performed cycle ergometer tests which 6 min of constant-load work (150, 200, 250W) followed 50W base line work. and Vo, measured at the mouth ((Vco2)E ((Vo2)_E) and estimated at the alveolar level ((Vco2)A, (Vo2)A) were computed breath-by-breath. The kinetic parameter (time constant) of first- and second·order exponential model was estimated using nonnear least-squares method. Our results demonstrated that a relative stability of PETO2, PETCO2, and R at their control values in the first phase. Independent of work intensities, breath-by-breath variation in gas exchange measured at the mouth was larger than those in gas exchange estimated at the alveolar level both at a non-steady state and a steady state. The time constants of (Vo2)A and (Vo2)E were varied with increase of work load intensity.
