Assessment of Cardio-Respiratory Relationship during and after Exercise in Healthy Recreative Male Subjects: A Pilot Study

Background: Understanding the responses of the cardio and respiratory systems during exercise, as well as their coupling in post-exercise recovery, is important for the prescription of exercise programs in physically recreative subjects. Aim: In this work, we aimed to set up an adjusted experiment to evaluate the relations and changes in parameters obtained from an analysis of cardiac and respiratory signals under three physiological conditions: relaxation, exercise, and post-exercise recovery. Material and Methods: Simultaneously recorded ECG (RR intervals) and respiratory signal during relaxation, bicycle ergometry exercise until submaximal heart rate (HR), and recovery in 10 healthy men were analyzed. The exercise included consecutive phases of 3 min in duration with a constant workload. Parasympathetic cardiac control (RMSSD), heart rate (HR), breathing frequency (BF), and respiratory cycle amplitude (RCA) were calculated. Anthropometric data were also collected. Results: Based on time series analysis, our results show that: (1) during exercise, an increase in HR was related to a reduction in HR variability and RMSSD, while an increase in BF was related to an increase in RCA, and (2) during recovery, HR and RCA significantly decreased, while RMSSD had a biphasic response. The results of multiple linear regressions showed that the averaged HR, RMSSD, and BF during 3 min segments of recovery were determined by several calculated and collected parameters. Conclusions: The parameters from the analysis of respiratory signals and RR interval time series under conditions of relaxation and exercise, along with anthropometric data, contributed to the complexity of the post-exercise recovery of cardiopulmonary parameters after submaximal HR exercise in healthy recreative males.