AUTHOR=Estévez-González Agustín Jesús , Donadio Márcio Vinícius Fagundes , Cobo-Vicente Fernando , Fernández-Luna Álvaro , Sanz-Santiago Verónica , Villa Asensi José Ramón , Iturriaga Ramirez Tamara , Fernández-del-Valle Maria , Diez-Vega Ignacio , Larumbe-Zabala Eneko , Pérez-Ruiz Margarita 

TITLE=Effects of a Short-Term Resistance-Training Program on Heart Rate Variability in Children With Cystic Fibrosis—A Randomized Controlled Trial

JOURNAL=Frontiers in Physiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.652029

DOI=10.3389/fphys.2021.652029

ISSN=1664-042X

ABSTRACT=<p><bold>Background:</bold> Cystic fibrosis (CF) affects the autonomic nervous system (ANS) and exercise in healthy children modulates the interaction between sympathetic and parasympathetic activity. This study aimed to evaluate the effects of a short-term resistance exercise program on heart rate variability (HRV) in children and adolescents with CF.</p><p><bold>Methods:</bold> A randomized controlled trial was carried out in children diagnosed with CF aged 6–18 years. Individuals were divided into two groups: control (CON) and resistance-training (EX). Individuals in the EX group completed an individualized guided resistance program (5-RM—60–80%) for 8 weeks (3 sessions of 60 min/week). Upper and lower limbs exercises (seated bench press, seated lateral row, and leg press) were used. HRV was measured using a Suunto watch with subjects in lying position.</p><p><bold>Results:</bold> Nineteen subjects (13 boys) were included (CON = 11; and EX = 8). Mean age was 12.2 ± 3.3, FEV<sub>1</sub> (forced expiratory volume in the first second) z-score was 1.72 ± 1.54 and peak oxygen consumption (VO<sub>2</sub>peak) 42.7 ± 7.4 mL.Kg<sup>–1</sup>.min<sup>–1</sup>. Exercise induced significant changes in the frequency-domain variables, including a decrease in LF power (<italic>p</italic> = 0.001, <italic>d</italic> = 0.98) and LF/HF ratio (<italic>p</italic> = 0.020, <italic>d</italic> = 0.92), and an increase in HF power (<italic>p</italic> = 0.001, <italic>d</italic> = −0.97), compared to the CON group. No significant changes were found for time-domain variables, although increases with a moderate effect size were seen for SDNN (<italic>p</italic> = 0.152, <italic>d</italic> = −0.41) and RMSSD (<italic>p</italic> = 0.059, <italic>d</italic> = −0.49) compared to the CON group.</p><p><bold>Conclusion:</bold> A short-term resistance exercise-training program was able to modulate HRV in children and adolescents with CF presenting mild to moderate lung function impairment and good physical condition.</p><p><bold>Clinical Trial Registration:</bold><ext-link ext-link-type="uri" xlink:href="http://www.ClinicalTrials.gov" xmlns:xlink="http://www.w3.org/1999/xlink">www.ClinicalTrials.gov</ext-link>, identifier NCT04293926.</p>