Gender difference in heart rate variability in medical students and association with the level of stress

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Background: Academic stress is the predominant stress in medical students, and there are studies conducted before on the assessment of stress during exams. However, medical students also face other kinds of stressors apart from academics which are present in their day to day activities. Heart rate variability (HRV) is a proved reliable non-invasive marker of cardiovascular health and has been used in the cardiovascular risk stratification. Aims and Objectives: This study was designed to compare the HRV in medical students and assess the association between the stress level and HRV in both genders. Materials and Methods: This was a cross-sectional analytical study, conducted in the Department of Physiology, Meenakshi Medical College, Kanchipuram, Tamil Nadu, India. 150 first year MBBS medical student volunteers were included in the study. 78 female and 72 male students were recruited for the study. The level of stress was assessed using the medical students’ stress questionnaire. Basal heart rate (BHR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were recorded by the oscillometric method using automated BP monitor Omron MX3 (Omron Healthcare Co. Ltd, Kyoto, Japan). Short-term HRV recording was done using lead II ECG. The data acquisition was done using 16 bit, 16 channel data acquisition system BIOPAC MP100 (BIOPAC Inc., Goleta, CA, USA) with AcqKnowledge 3.8.2 software (BIOPAC Inc., Goleta, CA, USA). Results: More female students have fallen in the category of high and severe stress in comparison to males. All the frequency domain indices (total power, low-frequency power, high-frequency power, and normalized high-frequency power [HFnu]) were reduced with increase in the intensity of stress except for LFnu, which significantly increased. With increase in the intensity of stress, BHR, SBP, DBP, pulse pressure (PP), and rate pressure product (RPP) were significantly increased. Females have significantly higher BP, BHR, PP, and RPP than males. All the HRV parameters and coefficient of variation parameters had a significant correlation with the cumulative stress score. Conclusion: We found that medical students are exposed to significant stressors during their medical training, and especially female students are more affected. With increase in the intensity of stress, the cardiovascular health of the student can get hampered with decreased HRV and increased BP and RPP.