Institute of Psychology, Faculty of Philosophy and Social Sciences, Nicolaus Copernicus University in Toruń, 87-100 Toruń, Poland.
Department of Informatics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, 87-100 Toruń, Poland.
Sensors (Basel). 2021 May 25;21(11):3670. doi: 10.3390/s21113670.
Scientific research on heart rate variability (HRV) biofeedback is burdened by certain methodological issues, such as lack of consistent training quality and fidelity assessment or control conditions that would mimic the intervention. In the present study, a novel sham HRV-biofeedback training was proposed as a credible control condition, indistinguishable from the real training. The Yield Efficiency of Training Index (YETI), a quantitative measure based on the spectral distribution of heart rate during training, was suggested for training quality assessment. A training fidelity criterion derived from a two-step classification process based on the average YETI index and its standard deviation (YETI) was suggested. We divided 57 young, healthy volunteers into two groups, each subjected to 20 sessions of either real or sham HRV-biofeedback. Five standard HRV measures (standard deviation of the NN (SDNN), root mean square of the standard deviation of the NN (RMSSD), total power, low-frequency (LF), and high-frequency (HF) power) collected at baseline, after 10 and 20 sessions were subjected to analysis of variance. Application of a training fidelity criterion improved sample homogeneity, resulting in a substantial gain in effect sizes of the group and training interactions for all considered HRV indices. Application of methodological amendments, including proper control conditions (such as sham training) and quantitative assessment of training quality and fidelity, substantially improves the analysis of training effects. Although presented on the example of HRV-biofeedback, this approach should similarly benefit other behavioral training procedures that interact with any of the many psychophysiological mechanisms in the human body.
心率变异性（HRV）生物反馈的科学研究受到某些方法学问题的困扰，例如缺乏一致的训练质量和保真度评估，或缺乏模拟干预的对照条件。在本研究中，提出了一种新颖的假 HRV 生物反馈训练作为一种可信的对照条件，与真实训练无法区分。基于训练期间心率的频谱分布的定量测量指标 Yield Efficiency of Training Index（YETI）被建议用于评估训练质量。基于平均 YETI 指数及其标准差（YETI）的两步分类过程，提出了一种训练保真度标准。我们将 57 名年轻健康的志愿者分为两组，每组接受 20 次真实或假 HRV 生物反馈。在基线、10 次和 20 次训练后，采集了五个标准 HRV 测量指标（NN 间期标准差的标准差（SDNN）、NN 间期均方根标准差（RMSSD）、总功率、低频（LF）和高频（HF）功率），并进行方差分析。应用训练保真度标准提高了样本的同质性，导致所有考虑的 HRV 指标的组间和训练间交互作用的效应大小都有了实质性的提高。应用方法学修正，包括适当的对照条件（如假训练）和训练质量和保真度的定量评估，大大改善了训练效果的分析。虽然本研究以 HRV 生物反馈为例，但这种方法也应该有益于与人体中许多心理生理机制中的任何一种相互作用的其他行为训练程序。
