Rogers Bruce, Giles David, Draper Nick, Mourot Laurent, Gronwald Thomas
College of Medicine, University of Central Florida, 6850 Lake Nona Boulevard, Orlando, FL 32827-7408, USA.
Lattice Training Ltd., Chesterfield S41 9AT, UK.
J Funct Morphol Kinesiol. 2021 Apr 26;6(2):38. doi: 10.3390/jfmk6020038.
Past attempts to define an anaerobic threshold (AnT) have relied upon gas exchange kinetics, lactate testing and field-based evaluations. DFA a1, an index of heart rate (HR) variability (HRV) fractal correlation properties, has been shown to decrease with exercise intensity. The intent of this study is to investigate whether the AnT derived from gas exchange is associated with the transition from a correlated to uncorrelated random HRV pattern signified by a DFA a1 value of 0.5. HRV and gas exchange data were obtained from 15 participants during an incremental treadmill run. Comparison of the HR reached at the second ventilatory threshold (VT2) was made to the HR reached at a DFA a1 value of 0.5 (HRVT2). Based on Bland-Altman analysis and linear regression, there was strong agreement between VT2 and HRVT2 measured by HR ( = 0.78, < 0.001). Mean VT2 was reached at a HR of 174 (±12) bpm compared to mean HRVT2 at a HR of 171 (±16) bpm. In summary, the HR associated with a DFA a1 value of 0.5 on an incremental treadmill ramp was closely related to that of the HR at the VT2 derived from gas exchange analysis. A distinct numerical value of DFA a1 representing an uncorrelated, random interbeat pattern appears to be associated with the VT2 and shows potential as a noninvasive marker for training intensity distribution and performance status.
过去定义无氧阈（AnT）的尝试依赖于气体交换动力学、乳酸测试和基于场地的评估。心率变异性（HRV）分形相关特性指标DFA a1已被证明会随着运动强度的增加而降低。本研究的目的是调查从气体交换得出的无氧阈是否与由DFA a1值为0.5表示的从相关到不相关的随机HRV模式的转变有关。在递增式跑步机跑步过程中，从15名参与者身上获取了HRV和气体交换数据。将在第二个通气阈（VT2）时达到的心率与DFA a1值为0.5时达到的心率（HRVT2）进行比较。基于布兰德-奥特曼分析和线性回归，通过心率测量的VT2和HRVT2之间存在很强的一致性（r = 0.78，p < 0.001）。达到平均VT2时的心率为174（±12）次/分钟，而达到平均HRVT2时的心率为171（±16）次/分钟。总之，在递增式跑步机斜坡上与DFA a1值为0.5相关的心率与通过气体交换分析得出的VT2时的心率密切相关。代表不相关、随机心跳模式的DFA a1的一个特定数值似乎与VT2相关，并显示出作为训练强度分布和运动表现状态的非侵入性标志物的潜力。
