van Rassel C R, Ajayi O O, Sales K M, Clermont C A, Rummel M, MacInnis M J
Faculty of Kinesiology, University of Calgary, Calgary, AB, T2N 1N4, Canada.
Canadian Sport Institute Alberta, Calgary, AB, T3B 6B7, Canada.
Eur J Appl Physiol. 2025 Jan;125(1):91-102. doi: 10.1007/s00421-024-05592-2. Epub 2024 Sep 5.
The short-term scaling exponent of detrended fluctuation analysis (DFAα1) applied to interbeat intervals may provide a method to identify ventilatory thresholds and indicate systemic perturbation during prolonged exercise. The purposes of this study were to (i) identify the gas exchange threshold (GET) and respiratory compensation point (RCP) using DFAα1 values of 0.75 and 0.5 from incremental exercise, (ii) compare DFAα1 thresholds with DFAα1 measures during constant-speed running near the maximal lactate steady state (MLSS), and (iii) assess the repeatability of DFAα1 between MLSS trials. Twelve runners performed an incremental running test and constant-speed running 5% below, at, and 5% above the MLSS, plus a repeat trial at MLSS. During 30-min running trials near MLSS, DFAα1 responses were variable (i.e., 0.27-1.24) and affected by intensity (p = 0.031) and duration (p = 0.003). No difference in DFAα1 was detected between MLSS trials (p = 0.597). In the early phase (~ 8 min), DFAα1 measures at MLSS (0.71 [0.13]) remained higher than the DFAα1 identified at RCP from the incremental test (0.57 [0.13]; p = 0.024). In addition, following ~ 18 min of constant speed running at MLSS, DFAα1 measures (0.64 [0.14]) remained higher than 0.5 (p = 0.011)-the value thought to demarcate the boundaries between heavy and severe exercise intensities. Accordingly, using fixed DFAα1 values associated with the RCP from incremental exercise to guide constant-speed exercise training may produce a greater than expected exercise intensity, however; the dependency of DFAα1 on intensity and duration suggest its potential utility to quantify systemic perturbations imposed by continuous exercise.
应用于心跳间期的去趋势波动分析（DFAα1）的短期标度指数可能提供一种方法，以识别通气阈值并指示长时间运动期间的全身扰动。本研究的目的是：（i）使用递增运动中DFAα1值0.75和0.5来识别气体交换阈值（GET）和呼吸补偿点（RCP）；（ii）将DFAα1阈值与接近最大乳酸稳态（MLSS）的恒速跑步期间的DFAα1测量值进行比较；（iii）评估MLSS试验之间DFAα1的可重复性。12名跑步者进行了递增跑步测试，并在低于、等于和高于MLSS 5%的速度下进行恒速跑步，外加一次MLSS重复试验。在接近MLSS的30分钟跑步试验期间，DFAα1反应是可变的（即0.27 - 1.24），并受强度（p = 0.031）和持续时间（p = 0.003）影响。MLSS试验之间未检测到DFAα1有差异（p = 0.597）。在早期阶段（约8分钟），MLSS时的DFAα1测量值（0.71 [0.13]）仍高于递增测试中在RCP处确定的DFAα1（0.57 [0.13]；p = 0.024）。此外，在MLSS下以恒速跑步约18分钟后，DFAα1测量值（0.64 [0.14]）仍高于0.5（p = 0.011）——该值被认为是区分重度和极重度运动强度的界限。因此，使用与递增运动中RCP相关的固定DFAα1值来指导恒速运动训练可能会产生高于预期的运动强度；然而，DFAα1对强度和持续时间的依赖性表明其在量化持续运动引起的全身扰动方面具有潜在效用。
