Integrative Medicine Research 9 (2020) 28–32 Contents lists available at ScienceDirect Integrative Medicine Research j o ur nal ho mepage: www.imr-journal.com Original Article Effects of yoga breathing practice on heart rate variability in healthy adolescents: a randomized controlled trial Maheshkumar Kuppusamy a,∗ , Dilara Kamaldeen b , Ravishankar Pitani c , Julius Amaldas d , Padmavathi Ramasamy b , Poonguzhali Shanmugam a , Venugopal Vijayakumar a a Government Yoga and Naturopathy Medical College and Hospital, Chennai, India b Department of Physiology, Sri Ramachandra Medical College and Research Institute, Chennai, India c Department of Community Medicine, Ramachandra Medical College and Research Institute, Chennai, India d Department of Biochemistry, Sri Balaji Dental College and Hospital, Bharath University, Chennai, India a r t i c l e i n f o Article history: Received 17 September 2019 Received in revised form 10 January 2020 Accepted 12 January 2020 Available online 20 January 2020 Keywords: Yoga Bhramari pranayama Autonomic function Heart rate variability Adolescents a b s t r a c t Background: This study was conducted among healthy adolescents to assess the effects of a yoga breathing practice (Bhramari pranayama, Bhr.P) towards cardiac autonomic function using heart rate variability (HRV) parameters. Methods: Of the 730 eligible subjects screened, 520 healthy adolescents who met the inclusion and exclu- sion criteria were randomly assigned to either yoga breathing group (n = 260) or control group (n = 260). The yoga breathing group practiced Bhr.P. five days a week for a duration of six months while the control group continued with their daily routine without any intervention. Outcome measures were time and frequency domain of HRV in both groups which were assessed before and after the intervention using Lead II ECG. Linear models were used in the analysis of short term HRV. Results: After 6 months of yoga breathing, the time domain parameters of short term HRV showed signif- icant (P < 0.05) improvement towards the parasympathetic domain. Frequency domain parameters also showed the same direction of changes. In contrast, control group subjects showed a trend towards a sympathetic domain. Conclusion: The present study showed a positive shift in cardiac autonomic modulation towards parasym- pathetic predominance after 6 months of yoga breathing practice among apparently healthy adolescents. © 2020 Korea Institute of Oriental Medicine. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Introduction Several types of school-based stress management and wellness programs have been developed with the purpose of encouraging healthy coping strategies and resilience among adolescents. 1 Ado- lescence is a vital period for the development of mental health, which also includes healthy coping responses to stress whereas today’s “typical child” is described as stressed out, under nour- ished, and sedentary. 2 One promising approach for this is yoga combines physical exercises, flexibility and strength with relax- ation and meditation/ mindfulness techniques. 3 Practicing yoga has been associated with numerous health ben- efits. Bhramari pranayama (Bhr.P) adopts simple regulation of ∗ Corresponding author: Government Yoga and Naturopathy Medical College and Hospital, Chennai 600106, India. E-mail address: doctor.mahesh1985@gmail.com (M. Kuppusamy). voluntary breathing and can be easily practiced by all irrespective of age or/and gender. Previous studies have mentioned that regu- lar practice of yoga breathing practice reduces the cardiovascular reactivity to stress (cold pressor test) by inducing parasympathetic predominance and cortico- hypothalamo medullary inhibition. 4,5 Reduction of heart rate, blood pressure and autonomic function were observed immediately after 5 min of yoga breathing practice in healthy volunteers and this also shows that it produces parasym- pathetic domination. 6 Enhanced inhibitory response and cognitive control were noted among the healthy individuals followed by 10 min of yoga breathing practice. 7 Electroencephalogram (EEG) studies have shown increased theta activity and paroxysmal gamma waves, following the yoga breathing practice, inducing the positive thought and feeling of happiness. 8 Yoga breathing has recently shown to improve the acoustic and aerodynamic parameters of voice in healthy subjects. 9 Our previous studies on adolescents also showed improvement in cardiovascular param- eters and pulmonary function test. 10,11 These are the very few https://doi.org/10.1016/j.imr.2020.01.006 2213-4220/© 2020 Korea Institute of Oriental Medicine. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).