1Universidad Pablo de Olavide, Sevilla, Spain.
2Universidad del Desarrollo, Santiago, Chile.
Physiol Int. 2020 Dec 24;107(4):501-512. doi: 10.1556/2060.2020.00039.
We aimed to analyse the complexity and fractal nature of heartbeat during constant exercise, at three different intensities, and recovery.Fourteen healthy men underwent 4 separate sessions. The first session was an incremental treadmill test to determine ventilatory thresholds (VT1 and VT2) and maximal aerobic speed (MAS). Each subject ran at VT1 and VT2 speeds and MAS (second, third and fourth day). The duration of VT1 and VT2 loads were selected in such a way that the product intensity-duration (training load) was the same. Sample Entropy (SampEn) and slope of Detrended Fluctuation Analysis (DFA α1) were measured during the whole session.DFA α1 declines with exercise, being less in the VT1 trial than in the other two.SampEn shows no significant change during exercise. The three tests induce the same decline in SampEn, but at the highest intensity (MAS) tends to decline during the exercise itself, whereas at lower intensities (VT1, VT2) the decline is delayed (10 min of recovery). Subsequently, SampEn at VT1 gradually recovers, whereas at VT2 and MAS it remains stable during recovery.In conclusion, exercise produces a loss of heartbeat complexity, but not fractal nature, during recovery and it depends on intensity.
我们旨在分析在恒定运动、三个不同强度和恢复期间的心跳复杂性和分形性质。十四名健康男性进行了 4 次单独的测试。第一次测试是递增跑步机测试，以确定通气阈值（VT1 和 VT2）和最大有氧速度（MAS）。每个受试者以 VT1 和 VT2 速度以及 MAS（第二天、第三天和第四天）进行跑步。选择 VT1 和 VT2 负荷的持续时间，以使强度持续时间乘积（训练负荷）相同。在整个测试期间测量样本熵（SampEn）和去趋势波动分析（DFA α1）斜率。DFA α1 随运动而下降，在 VT1 试验中比其他两个试验中的值小。SampEn 在运动期间没有明显变化。这三个测试都导致 SampEn 相同程度的下降，但在最高强度（MAS）时，在运动本身期间趋于下降，而在较低强度（VT1、VT2）时，下降会延迟（恢复 10 分钟）。随后，VT1 时的 SampEn 逐渐恢复，而在 VT2 和 MAS 时，在恢复期间保持稳定。总之，运动导致心跳复杂性在恢复期间丧失，但分形性质不变，而且取决于强度。
