Evaluation components of the heart rate kinetics for assessment cardiac adaptation during rehabilitation

"The purpose of the study was assessment of the cardiovascular adaptation to the workload and physical training by analysis of the heart rate kinetics and dynamics of power spectrum components in healthy subjects and ischemic heart disease patients during rehabilitation. The contingent of study was 20 healthy subjects and 97 patients post-myocardial infarction (74 without chronic heart failure and 23 with chronic heart failure symptoms). Multistage bicycle ergometry or spiroergometry and computerized analysis of heart rate variability during active orthostatic, symptom-limited workload tests and recovery period after test were performed. The rhythmogram at 50W of the workload, and during bicycle (Kettler) training and recovery period was analyzed and the time constant (?) of the exponential function (by using Proni method), coefficients of amplification, rapidity as well as heart rate (HR) power spectral components (?VLF, ?LF, ?HF) were evaluated. Heart rate kinetics response time constant to the low-level (?50W) workload (30.3 vs. 19.3 s) and during recovery period (40 vs. 45.6 s) was delay in post-myocardial infarction patients, especially in those with CHF and low physical capacity as compared with healthy subjects. Heart rate responses (?50W) correlated with baseline HR autonomic control components (?LF, r=-0.25, ?RRB%, r=-0.24, RRB, r=0.23,) and with physical capacity (r=-0.30). In CHF patients the delay HR response to the workload and during recovery correlated with expressed ventilatory response (VE/VCO2, r=0.60) in this group. Positive dynamic of HR kinetics components (?=37.1 vs. 34.6 s) and power spectrum characteristics after low intensity bicycle training procedure and during recovery (?=42.4 vs. 39.9 s) period was observed. The faster HR reaction to the physical stressor after 3-weeks bicycle training correlated with positive dynamics of ?HF (r=-0.35). The HR power spectrum components during bicycle training changed favorably (?VLF, 15.2 vs. 16.3 ms; ?LF, 8.2 vs. 9.4 ms; ?HF, 8.8 vs. 9.4 ms) too. Conclusions. Analysis of the heart rate kinetics components and power spectrum data during exercise provides a new possibility evaluation of the cardiac adaptation to the workload and physical training procedures in ischemic heart disease patients during rehabilitation"