Identification of steady states and quantification of transition periods from beat-by-beat cardiovascular time series: application to incremental exercise test

A recently proposed procedure for checking the cardiovascular steady state from beat-by-beat values of blood pressure and heart rate was used for investigating incremental exercise tests. We measured conrinuous blood pressure in 5 volunteers during rest, incremenial exercise until volitional exhaustion, and recovery, and derived a “steadiness profile” over the whole recording. During exercise, the level of steadiness was higher in the best trained subjects. Steady state was lost at the maximum workload, WL- in all the subjects. Recovery time, measured as the period io reach a new steady state after exercise, seems fo be inversely related to WL_max ranging from 254s for the best trained subject (WL_max = 275W) to 350s for the less trained one (WL_max = 175W). The analysis showed that the procedure can check the hypothesis of steady srate during exercise tests, and provide useful informutian to better describe fhe level of physical fitness.