Cardiac reserve mobilization trend during exercise and recovery after exercise

Objective: Little is known about the cardiac contractility recovery after exercise. The objective of the study was to explore a method to evaluate the extent and speed of cardiac function up-regulation during exercise and the recovery course of cardiac contractility and heart rate after exercise. Methods: Ten student athletes and ten student non-athlete voluntarily participated in this controlled study. Three indicators were selected: 1) amplitude ratio of the first to second heart sound (S1/S2); 2) heart rate (HR); 3) power output (W). Phonocardiogram exercise test (PCGET) was adopted. A four-stage workload increment protocol was used. Phonocardiograms were recorded in the sitting position at rest and immediately after each test stage. The time taken for completing the workloads 1750 J, 3500 J, 5250 J, and 7000 J was recorded, respectively. During recovery heart sound signals were recorded immediately after exercise, and at 1, 5, 10, 15, 20, 25, and 30 minutes after exercise. S1/S2, HR, and W were calculated from the measured data. Cardiac function change trend graphs were constructed. Results: During exercise, HR and S1/S2 ratio increased with the increase in workload from 1750 J to 7000 J; the level and speed of increase in power output and S1/S2 ratio of the athletes were higher than the general students; power done by the general students decreased earlier than the athletes. During recovery course, the recovery course of the general students was slower than the athletes. Conclusion: This method for evaluating cardiac function up-regulation and recovery course is safe, easy, reliable, and effective, which is beneficial for selecting athletes, training, and matchmaking.