Faculty of Kinesiology, University of Calgary, Calgary, Canada.
Applied Physiology and Nutrition Research Group - Center of Lifestyle Medicine, Faculdade de Medicina FMUSP, Universidade de São Paulo, São Paulo, Brazil.
Physiol Rep. 2023 Aug;11(15):e15782. doi: 10.14814/phy2.15782.
An index of heart rate variability (HRV), detrended fluctuation analysis (DFA a1) has gathered interest as a surrogate marker of exercise intensity boundaries. The aim of this report was to examine heart rate variability threshold (HRVT) behavior across different ramp incremental (RI) slopes. Seventeen participants completed a series of three RI (15, 30, and 45 W · min slopes) with monitoring of gas exchange parameters, heart rate (HR) and HRV. HRVT1 was defined as the V̇O or HR at which DFA a1 reached 0.75 and the HRVT2 at which these values reached 0.5. HRVTs were compared by Pearson's r, Bland-Altman analysis, ICC , ANOVA, and paired t-testing. An excellent degree of reliability was seen across all three ramps, with an ICC of 0.93 and 0.88 for the HRVT1 V̇O and HR, respectively, and 0.90 and 0.92 for the HRVT2 V̇O and HR, respectively. Correlations between HRVT1/2 of the individual ramps were high with r values 0.84-0.95 for both HR and V̇O . Bland-Altman differences ranged between -1.4 and 1.2 mL · kg · min and -2 and +2 bpm. Paired t-testing showed no mean differences between any HRVT1/2 ramp comparisons. Cycling ramp slope does not appear to affect either HRVT1 or HRVT2 in terms of HR or V̇O .
心率变异性（HRV）的指数，去趋势波动分析（DFA a1）作为运动强度界限的替代标志物引起了关注。本报告的目的是研究不同递增斜坡（RI）斜率下心率变异性阈值（HRVT）的行为。17 名参与者完成了一系列 3 个 RI（15、30 和 45 W·min 斜率），监测气体交换参数、心率（HR）和 HRV。HRVT1 定义为 DFA a1 达到 0.75 的 V̇O 或 HR，而 HRVT2 则是这些值达到 0.5 的 V̇O 或 HR。通过 Pearson r、Bland-Altman 分析、ICC、ANOVA 和配对 t 检验比较 HRVT。所有三个斜坡都显示出极好的可靠性程度，HRVT1 V̇O 和 HR 的 ICC 分别为 0.93 和 0.88，HRVT2 V̇O 和 HR 的 ICC 分别为 0.90 和 0.92。个体斜坡的 HRVT1/2 之间的相关性很高，HR 和 V̇O 的 r 值分别为 0.84-0.95。Bland-Altman 差异在-1.4 和 1.2 mL·kg·min 和-2 和+2 bpm 之间。配对 t 检验显示，任何 HRVT1/2 斜坡比较之间均无均值差异。就 HR 或 V̇O 而言，自行车斜坡斜率似乎不会影响 HRVT1 或 HRVT2。
