Department of Exercise and Health Sciences, University of Massachusetts Boston, Boston, Massachusetts, USA.
Departamento de Ciencias Básicas, Facultad de Medicina, Universidad Católica de la Santísima Concepción, Concepción, Chile.
Physiol Rep. 2023 Feb;11(4):e15616. doi: 10.14814/phy2.15616.
Sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) influences on cardiac rhythm at the onset of exercise, a time of rapid autonomic adjustments, are clinically important areas of investigation. Continuous wavelet transform (CWT) involves time-frequency-based heart rate variability (HRV) analysis allowing investigation of autonomic influences on cardiac rhythm during short durations of exercise. Therefore, the purpose of this study was to characterize SNS and PNS influences on cardiac rhythm at the onset of isometric exercise in healthy young adults. CWT analysis was retrospectively applied to R-R interval data (electrocardiogram) previously collected from 14 healthy young adults (26 ± 2 years) who performed 30-s, one-legged, isometric, calf exercise at 70% maximal voluntary contraction (MVC; 70% MVC trial) or rested (0% MVC trial). Absolute and normalized low-frequency (aLF, nLF; 0.04-0.15 Hz) and high-frequency (aHF, nHF; 0.15-0.4 Hz) bands and LF/HF were used to analyze one 30-s baseline period and six 5-s time windows during the 30-s exercise (70% MVC) or rest (0% MVC). Statistical analysis involved two-way analysis of variance with post-hoc analysis. aHF, aLF, LF/HF, nHF, and nLF displayed a trial-time interaction (all p ≤ 0.027). In the 70% compared to the 0% MVC trial, aHF and nHF were lower after 5-30 s (all p ≤ 0.040), aLF was lower after 20-30 s (all p ≤ 0.011) and LF/HF and nLF were higher after 5-20 s (all p ≤ 0.045). These results indicate the reduction of the PNS influence on cardiac rhythm begins sooner than the augmentation of the SNS influence at the onset of isometric exercise in healthy young adults.
自主神经系统（SNS）和副交感神经系统（PNS）对运动开始时的心率的影响是临床研究的重要领域，这一时间点自主神经会迅速调整。连续小波变换（CWT）涉及基于时频的心率变异性（HRV）分析，允许在短时间的运动过程中研究自主神经对心率的影响。因此，本研究的目的是描述健康年轻成年人等长运动开始时 SNS 和 PNS 对心率的影响。CWT 分析回顾性地应用于从 14 名健康年轻成年人（26±2 岁）收集的 R-R 间期数据（心电图），他们进行了 30 秒、单腿、等长、小腿运动，强度为 70%最大自主收缩（70% MVC 试验）或休息（0% MVC 试验）。绝对和归一化低频（aLF、nLF；0.04-0.15 Hz）和高频（aHF、nHF；0.15-0.4 Hz）带和 LF/HF 用于分析 30 秒运动（70% MVC）或休息（0% MVC）期间的 30 秒内的一个 30 秒基线期和六个 5 秒时间窗口。统计分析包括双因素方差分析和事后分析。aHF、aLF、LF/HF、nHF 和 nLF 显示出试验时间的相互作用（所有 p≤0.027）。与 0% MVC 试验相比，70% MVC 试验中 aHF 和 nHF 在 5-30 秒后降低（所有 p≤0.040），aLF 在 20-30 秒后降低（所有 p≤0.011），LF/HF 和 nLF 在 5-20 秒后升高（所有 p≤0.045）。这些结果表明，在健康年轻成年人等长运动开始时，PNS 对心率的影响减少早于 SNS 对心率的影响增加。
