Short-Term High-Intensity Interval Training Is Superior to Moderate-Intensity Continuous Training in Improving Cardiac Autonomic Function in Children

Abstract

Objectives: This study aimed to investigate the impact of 3 isocaloric exercise programs on cardiac autonomic nervous system (ANS) functioning in children. Methods: One hundred nine children (39% boys and 61% girls) aged 10–13 years (mean 11.07 ± 0.81) were conveniently assigned to 1 of 4 groups as follows: Moderate-intensity continuous training (MICT; n = 29) at 65–70% of the predicted maximum heart rate (MHR), High-intensity interval training (HIIT; n = 29) at > 80% of the predicted MHR, HIIT and MICT combined on alternate weeks (ALT; n = 27), and a control group (n = 24). Morning ANS activity was assessed via analysis of heart rate variability (HRV), with the patient in supine position for 10 min, before and after the exercise intervention. Data Analysis: A 2-way analysis of variance was used to evaluate the effects of training on all HRV parameters (p < 0.05/4 = 0.0125). Results: After 5 weeks of training, significant improvements were observed for ln of the standard deviation of normal-to-normal intervals (p < 0.0001), ln of the root mean square of successive difference (p < 0.0001), and ln of standard deviation 1 (p < 0.0001), with superior results reported in the HIIT group (effect size [ES] = 2.22, 2.69, and 2.69) compared with the MICT (ES = 1.67, 1.75, and 1.75) and ALT (ES = 0.87, 1.06, and 1.06) groups, respectively. Conclusion: Short-term HIIT seems to induce superior alterations in cardiac ANS activity compared to MICT and ALT in children through enhanced vagal activity.

Analysis of high-intensity physical activity biological feasibility within the framework of children health training

“…Another research compared the effects of implementation of HIIT and MICT protocols for adolescent cardiac activity. During a five-week experiment, which was based on an analysis of heart rate variability, the prevailing advantageous effect of the implementation of HIIT protocol on adolescent cardiac activity by means of increased vagal activity was proved [19].…”

Lifestyle Modification for Enhancing Autonomic Cardiac Regulation in Children: The Role of Exercise

“…Global guidelines recommend that children aged 5–17 years old should engage in at least 60 min of moderate to vigorous PA daily with higher training loads and intensities imparting greater health benefits [20]. Regarding childhood exercise interventions for enhancing ANS cardiac regulation, frequency of sessions ranged from 3 days per week to daily sessions with individual session durations ranging from 20 min up to 2 h [14,18,21,22,23,24,25,26,27,28]. Intensity of sessions were typically performed at a moderate to vigorous percentage of heart rate reserve (40–85%) [29].…”

“…Whether the frequency of training sessions was a minimum of 3 days/week or daily training sessions, findings consistently displayed positive effects on child ANS cardiac regulation (i.e., increased PNS parameters and total HRV) [14,21,22,23,24,25,26,27,28]. Similarly, training sessions from 20 min up to 2 h positively impacted child cardiac ANS regulation [14,21,22,23,24,25,26,27,28]. However, the intensity of exercise sessions (i.e., moderate, vigorous, maximal, and supramaximal) may have an essential influence on child ANS regulation and, thus, PA guidelines that only give recommendations based on total daily volume are inadequate.…”

“…In a study by Gamelin et al, after a 7-week intervention of maximal and supramaximal aerobic exercise training of a relatively low training load (i.e., three, 30-min sessions/week), there were no significant differences in HRV (and no improvements) in the exercise intervention group as compared with the control group [18]. The authors proposed that the 7-week intervention may have been too short to improve HRV, although shorter, aerobic exercise investigations involving similar session duration and sessions/week demonstrated enhanced cardiac vagal regulation in their participants [14]. A notable difference in the exercise dose prescribed by Gamelin et al compared with other studies was the maximal and supramaximal exercise intensity.…”

“…One lifestyle modification for enhancing ANS regulation in children is proposed to be via the increase in appropriate exposure to exercise, which has been shown to benefit overall health and wellbeing [13]. Moreover, low PA participation appears to be associated with decreased PNS activity/cardiac vagal tone and increased prevalence of diseases associated with cardiac autonomic neuropathy (i.e., cardiovascular disease, DM, hypertension) [14,15,16]. Although previous findings indicate a positive relationship between exercise and HRV, optimal and safe training loads for enhancing ANS cardiac regulation should be considered as over-training or insufficient recovery may potentially lead to dysregulated ANS activity [17,18].…”