Analysis of Dynamic Cardiopulmonary Signals and Heart Rate Variability for Distinct Cardiopulmonary Fitness Norms under Graded Exercise and Recovery Periods

This study performed a comparison based on electrocardiogram (ECG) signals for participants with distinct levels of cardiopulmonary fitness at graded exercise intensities. The participants were university freshmen with cardiopulmonary fitness norms in the bottom 20%, middle, and top groups. Cardiopulmonary signals were acquired under the rest condition, at three graded exercise levels, and in subsequent recovery periods. Time domain and spectral analyses were performed to study the principal components of heart rate variability (HRV) from recorded ECG signals. The results showed that the frequency domain measures TP, HF, nLF, nHF, and LF/HF of the HRV indices all exhibit significant differences between the three groups.