Cardiac Autonomic Modulation in Preadolescents Following 4 and 8 Weeks of Play-based Summer Activity

Marco Meucci ,C Cook M S,Laura Guidetti ,Carlo Baldari ,Jonato Prestes ,Sr Collier

doi:10.21767/2572-5394.100006

Abstract

Pediatric obesity is associated with a decrease in cardiac autonomic modulation and baroreflex sensitivity. Physical activity increases heart rate variability in adults, yet no study has elucidated the mode and intensity of exercise for beneficial effects on cardiac autonomic modulation in children. Objective: The purpose of our study was to examine the effectiveness of 4 and 8 weeks of supervised, play-based activity on blood pressure, heart rate variability and baroreflex sensitivity in preadolescents. Methods: Twenty-two recreationally active overweight, 8 to 12 year-old children were randomly divided into a 4- and 8-week activity group and an unsupervised control group (4w, n = 6, 8w, n = 6, and C, n = 10). 4w and 8w groups performed play-based activities 5 days per week, 4 hours a day while C group were instructed to maintain a regular summer break with no supervised intervention. Heart rate variability and baroreflex sensitivity were tested before and after exercise with a heads-up tilt test. Results: Systolic blood pressure was significantly lower in all three groups in post conditions (P = 0.02, eta2 = 6.86). Normalized low and high frequencies reported a significant group-by-time difference in both supine resting conditions and after heads-up tilt (P = 0.04, eta2 = 0.28 and P = 0.05, eta2 = 0.28, respectively) and total power in supine position (P = 0.04, eta2 = 0.29) between the 8w, and the 4w and C groups, while baroreflex sensitivity increased by only 3 ms/mmHg in the 8w group (P = 0.09). Conclusion: 8 weeks of supervised, play-based physical activity improved autonomic nervous system activation with favorable changes in sympathovagal balance in recreationally active overweight preadolescents during summer break.

Highlights

The adoption of a sedentary lifestyle has become a serious epidemic in adults and children and it is increasingly disconcerting since it is associated with an increase in the clinical manifestation of cardiovascular disease
Low heart rate variability (HRV) is indicative of reduced cardiac autonomic modulation (CAM), which is commonly used as a clinical tool to predict cardiac morbidity and mortality [2,3]
It is well known that fit individuals have greater CAM compared to the sedentary counterpart [7,8] and studies in obese adolescents have demonstrated that physical activity augments cardiovascular autonomic function [1,9,10] lending clinical utility to a population that is at-risk for cardiovascular and metabolic disorders [11]

Summary

Introduction

The adoption of a sedentary lifestyle has become a serious epidemic in adults and children and it is increasingly disconcerting since it is associated with an increase in the clinical manifestation of cardiovascular disease. Previous studies shown that overweight/obese children have lower heart rate variability (HRV) than their normal weight counterpart and that HRV is positively correlated with physical activity levels [1]. It is well known that fit individuals have greater CAM compared to the sedentary counterpart [7,8] and studies in obese adolescents have demonstrated that physical activity augments cardiovascular autonomic function [1,9,10] lending clinical utility to a population that is at-risk for cardiovascular and metabolic disorders [11]. The most appropriate type of physical activity for preadolescents has yet to be established

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