Evaluation of Cardiac Autonomic Function in Relation to Post-Exercise Heart Rate Recovery Among Medical Students

Abstract

Introduction: Heart rate variability is the indicator that reflects the cardiovascular autonomic nervous system. Regular exercise stimulates structural and functional changes in the cardiovascular and peripheral system that can be measured by heart rate variability. This study was necessary to evaluate cardiac autonomic tone and its relation with physical fitness level in healthy medical students. So that it could provide important data regarding autonomic status and physical status which will be useful for both clinical and research purposes. Aims: To measure cardiac autonomic tone of medical students using heart rate variability and to look for the relationship between recovery heart rate and cardiac autonomic tone. Methods: In this cross-sectional study, 57 consenting healthy medical students age 17-30 years, underwent cardiac autonomic tone evaluation through heart rate variability and the cardiac autonomic tone was compared with their physical fitness level which was categorized into four groups that is good, satisfactory, poor and very poor. Results: No changes in Heart rate variability among four fitness groups were found. But when Spearman’s correlation was done we found out association of heart rate variability measures with recovery heart rate. The recovery heart rate showed significant negative correlation with pNN50, high frequency power and high frequency normalized unit. Whereas, recovery heart rate showed significant positive correlation with low frequency normalized unit and Low frequency/ high Frequency ratio of frequency domain measures of heart rate variability. Conclusion: This study reflects that parasympathetic activity was higher in increasing fitness level. But in lower fitness level sympathetic activity was higher.