Abstract
Background: Heart rate recovery (HRR), an important independent risk factor for cardiovascular disease and mortality is often used in research to study the cardiac autonomic status of an individual. Studies have shown that the HRR is impaired in men with metabolic syndrome, suggesting a deranged autonomic function in these individuals. An association has been found between HRR and the metabolic syndrome as well as between HRR and each of the components of this syndrome. It is well-known that HRR after exercise can be modified by weight loss, but the mechanism underlying the improvement of HRR is unclear.

Aims and Objectives: The aim of this study is to assess and compare the exercise-induced changes in the cardiac autonomic status of young overweight and obese sedentary females and females with normal body mass index (BMI) using HRV.

Materials and Methods: BMI and Waist/Hip ratio of 40 apparently healthy females recruited was calculated, and they were divided (following the WHO guidelines for Asians) into two groups: (1) Test group – BMI >23 Kg/m2 and W/H>0.8 and (2) control group - BMI 18.5 to 22.9 Kg/m2 and W/H<0.8. The level of physical activity of the study participants was assessed using the IPAQ questionnaire. Pre- and post-exercise ECG were recorded in all the females in lead II configuration. Short-term HRV analysis was performed with Kubios HRV software and tests of significance was done using repeated measures of ANOVA and Mann-Whitney U test using SPSS software version 23.

Results: Not pre-exercise, but post-exercise time domain parameters were significantly differing at 1 min, 15 min, and 30 min after exercise in the test group, whereas, frequency domain parameters were showing significant differences (high LF nu, low HF nu, high LF/HF ratio) before as well as after exercise in the test group, but not significant in the control group.

Conclusion: This shows that the sympathetic dominance after exercise is prolonged in females with higher BMI and recovery to the baseline is delayed. Hence, it is likely that these individuals could develop hypertension and other cardiac complications in their future life. Hence, the improvement of regular physical activities must be stressed on among these young females.

Key words: Heart Rate Variability; Body Mass Index; Sympathetic Dominance