Heart Rate Variability; A 16-Week Examination of Stress (PDF)

AN EXAMINATION OF BASIC BIOMETRIC VARIABLES AND PHYSICAL ACTIVITY ON HEART RATE VARIABILITY Cara E. Zinn, Alex DiSerio B.S., Ayla Kibler B.S. Faculty Mentors: Karen K. Dennis, RN, Ed.D. and Alex M. Wolfe, M.S. School of Kinesiology and Recreation Illinois State University Abstract The subjects for this research were 23 students enrolled in KNR 113 Personal Fitness. Each student signed an informed consent form. The duration of this study lasted one academic semester (16-weeks). All participating students were assigned a pedometer to track their daily steps. Each student had biometric data (height, weight, body composition,VO2 (ml/kg/min), and HRV collected at the beginning and end of the semester. HRV measurements were taken using the HeartMath emWave pro software using an infrared pulse plethysmograph ear sensor. Physical Activity data was collected each week of the course through self-reported pedometer logs. Lifestyle education and exercise were the primary focus of the curriculum for the class. “Release It” stress management technique education assignments were given through the HeartMath Institute, and focused on breathing techniques, attitude, and the heart-brain connection. Introduction Methodology References Conclusions Results This study provides positive and useful information about the use of physical activity and stress management education for impacting HRV. However, it is unclear whether physical activity or stress management training attributed to the significant differences in pre- to post- HRV testing. Our next step is to include a perceived stress questionnaire for participants to complete both at the beginning and at the end of the course. This information may shed light on the effectiveness of the stress management education and help identify to what extent each variable has on heart rate variability. Heart rate variability (HRV) is described as the time interval between heartbeats and is an important aspect of overall health. Stress is a phenomenon that influences HRV. During stressful events the sympathetic nervous system is aroused. Physiologically, stress appears in the form of lowered HRV, with decreased parasympathetic (PS) activity, increased sympathetic (S) activity, and increased levels of cortisol.Alternatively, shifting the autonomic balance towards increased PS activity can be achieved through stress managing training and practice. Rhythmic breathing and active self-generating positive emotion training may shift the ANS balance towards increased PS activity (Culbert, Martin & McCraty, 2014). Research has also established a relationship between physical activity (PA) and HRV. Many studies have stated that as PA increases, heart rate decreases, while HRV increases. Our previous studies have demonstrated the relationship between physical activity, physical fitness and HRV, including significant findings when separating PA by intensity (Dennis and Wolfe, 2016), PA and PA intensity had a larger impact on HRV rather than weight status (as measured by BMI) (Dennis, Wolfe, & Ward, 2018), and achievement of moderate intensity physical activity recommendations may have a greater influence on stress then total steps per day (Dennis et al., 2018). This pilot study does not tell us, however, which aspect of the course it is that contributes to the positive results in HRV. The physical activity, the stress management education, or a combination of both could be at work. Height, weight, BMI, and percent body fat did not have statistically significant changes or effect on pre to post HRV test results. PURPOSE: Investigation of the effects of physical activity and biometric variables on heart rate variability (HRV) over the course of a semester-long (16- week) course designed around lifestyle education and stress management training. METHODS: 23 subjects from KNR 113 Personal Fitness at Illinois State University were used to gather data. During the full duration (16-weeks) of this study, students were given a pedometer to track their total steps per day. Students also participated in physical activities aimed at increasing fitness measures. Assignments were given throughout the course from the HeartMath Institute website for education of stress management techniques. HRV measurements were taken at the beginning and end of the research study using the HeartMath emWave pro software measured by a pulse plethysmograph ear sensor. RESULTS: There were statistically significant changes in multiple variables between the pre- and post-tests, including V02 (ml/kg/min), resting heart rate, SDNN (ms) (HRV), and daily steps. CONCLUSION: Although statistically significant improvement was observed in SDNN (HRV), it cannot be concluded which aspect of the course contributed the most to this change, or if a combination of physical activity/fitness improvement along with stress management education could be at work. Culbert, T.P with Martin, H. & McCraty, R. (2014). A Practitioner’s Guide. Applications of the emWave Pro Stress Relief System. HeartMath LLC: Boulder Cree, CA. Dennis, K.K.. Wolfe, A. M., & Ward, S. (2018). Physical Activity or Body Composition for Heart Health & Heart Rate Variability. Medicine & Science in Sports & Exercise, 50(5S), 21. Dennis, K., & Wolfe, A. (2016, October). The Relationship Between Physical Activity Intensity and Heart Rate Variability. Paper presented at the All- Russian Physical and Sport Complex “Ready to Work and Defense (TRP)” and Mass Sports in the System of Healthy Lifestyle of Population, Vladimir, Russia. Abstract # 23. Abstract retrieved from https://elibrary.ru/item.asp?id=28081736 Dennis, K.K., Wolfe, A.M., Kibler, A., DiSerio, A., Mahoney, D., Pilli, N., & Von Schaumburg, L. (Nov. 28 – Dec. 1, 2018). The relationship between physical activity, perceived stress, and heart rate variability. Paper presented at the II International Scientific and Practical Conference, Vladimir, Russia. Vladimir State University ISBN 978-5-9984-0995-0. Kleiger, R.E., Miller, J.P., Bigger, J.T., Jr. & Moss, A.J. (1987). Decreased heart rate variability and its association with increased mortality after acute myocardial infarction. American Journal of Cardiology. 59(4): 256-262. Purpose The purpose of this study was to continue to investigate the effects of PA and other biometric variables on HRV over the course of a semester-long (16-week) course designed around lifestyle education and stress management HRV training. A t-Test paired two sample for means was conducted to test for statistical significance. Results indicated that there were statistically significant changes in multiple biometric variables from the pre- to the post-test. Table 1 shows the pre-and post-test scores of the variables, with statistically significant changes revealed in V02 (ml/kg/min), resting heart rate, SDNN measurement of HRV and steps.