AUTHOR=Jabbour Georges , Iancu Horia D. 

TITLE=Supramaximal-Exercise Training Improves Heart Rate Variability in Association With Reduced Catecholamine in Obese Adults

JOURNAL=Frontiers in Physiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.654695

DOI=10.3389/fphys.2021.654695

ISSN=1664-042X

ABSTRACT=<p>This study investigates the effect of 6 weeks of supramaximal exercise training (SET) on heart rate variability (HRV) and associated factors in sedentary obese (OB) and normal-weight (NW) adults. In this study, 19 OB [22.9 (8.4) years; body mass index (BMI) 33.4 (1.4) kg/m<sup>2</sup>] and 18 NW [23.2 (4.4) years; BMI 23.3 (1.2) kg/m<sup>2</sup>] adults completed a 6-week SET intervention. Anthropometric and aerobic indicators as well the homeostasis model assessment index for insulin resistance index (HOMA-IR) were assessed at baseline and after SET. The low- and high-frequency [(LF (0.03–0.15 Hz) in ms<sup>2</sup> and HF (0.15–0.4 Hz) in ms<sup>2</sup>)] analysis of HRV as well as adrenaline (A in nmol/l) and noradrenaline (NA in nmol/l) responses were assessed at resting condition and during ventilatory threshold 1 (VT1) of a graded maximal test at baseline and after SET. At baseline, resting HF, LF and the LF/HF ratio were different among groups (<italic>P</italic> &lt; 0.01, respectively) and were significantly associated with waist-to-hip ratio (β = −0.26; <italic>p</italic> = 0.01, β = −0.12; <italic>p</italic> = 0.01 and, β = 0.21; <italic>p</italic> = 0.01). During exertion at VT1, only LF/HF ratio was associated with NA responses (β = 0.23; <italic>p</italic> = 0.01). After SET, the frequency domain marker improved significantly for both groups in comparison to baseline. These improvements are manifested by LF and HF increases and LF/HF ratio decreases in the rest condition (<italic>p</italic> &lt; 0.01, respectively) and during exertion at VT1 (<italic>p</italic> &lt; 0.01, respectively). The improvement in LH and HF were associated with VO<sub>2</sub>max increases (β = 0.22 <italic>p</italic> = 0.01 and β = 0.33; <italic>p</italic> = 0.01). The decreases observed for the LF/HF ratio are mainly associated to NA decreases observed at rest (β = 0.31; <italic>p</italic> = 0.001) and at VT1 (β = 0.38; <italic>p</italic> = 0.001). Obese adults have altered HRV, and 6 weeks of SET improves HRV variables at rest and during VT1 exertion. While LF and HF improvement were associated with VO2max increases, the LF/HF ratio was mainly associated with noradrenaline decreases observed at rest and at VT1.</p>